Ac problem
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Ac problem
My civic 05 ex 5 speed has had an ac problem for sometime now and have not been able to figure out whats wrong.Any opinions would be appreciated. The symptoms that iam experiencing with the ac are:
1.The ac control button light to turn on and off(push), has had a change in polarization or when i turn the compressor on, the light is off and when its off the light is on.
2.The ac engages and disengages when in idle, but if i turn the ac on while in idle and start driving the ac does not want to disengage and my lines freeze over.
3. On really cold mornings before i go to school, once i turn the car on, the ac automatically engages and i cannot turn it off period and sometimes you hear like short circuit by the fuse box under the hood and the ac is engaging and disengaging like crazy and rpms rev up and down by about 100. Only when its cold outside which confuses me
. When this happens i decide to disconnect the relay that controls the ac clutch and the ac clutch does disengage but the short circuit sound in the fuse box under the hood gets worse.im afraid my car will catch on fire 
4.Last but not least on top of all that i realized that even when ac clutch does not want to disengage, it does not even cycle at the least either which causes my lines to freeze over.
So if anyone can get back at me for those 4 problems im having, i would really appreciate it. Its been driving me crazy.
1.The ac control button light to turn on and off(push), has had a change in polarization or when i turn the compressor on, the light is off and when its off the light is on.
2.The ac engages and disengages when in idle, but if i turn the ac on while in idle and start driving the ac does not want to disengage and my lines freeze over.
3. On really cold mornings before i go to school, once i turn the car on, the ac automatically engages and i cannot turn it off period and sometimes you hear like short circuit by the fuse box under the hood and the ac is engaging and disengaging like crazy and rpms rev up and down by about 100. Only when its cold outside which confuses me
. When this happens i decide to disconnect the relay that controls the ac clutch and the ac clutch does disengage but the short circuit sound in the fuse box under the hood gets worse.im afraid my car will catch on fire 4.Last but not least on top of all that i realized that even when ac clutch does not want to disengage, it does not even cycle at the least either which causes my lines to freeze over.
So if anyone can get back at me for those 4 problems im having, i would really appreciate it. Its been driving me crazy.
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Re: Ac problem
2-4 Bad pressure switch maybe? The relay switch might be bad or stuck also, Low refrigerant could also cause this sometimes.
1. did you replace the switch or anything like that, where the wires could have been put back on wrong?
Sometimes this whole problem can be traced to the ECU but i would rule out other options first.
1. did you replace the switch or anything like that, where the wires could have been put back on wrong?
Sometimes this whole problem can be traced to the ECU but i would rule out other options first.
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well the refrigerant is good so we can rule that out but what do you mean the relay switch is stuck? because if i disconnect the relay the ac clutch turnsoff and so does the ac which is good so i dont think its the clutch thats bad but like i said you start hearing a electrical sound in the fuse box where the relay goes like a short circuit. Oh and how much to get your pressure switch changed. and also are we talking about the same relay here? Im kinda of a noob to vehicles sorry. You also referred to wires being put back on wrong, which wires are you referring to, the ones that connect to the ac control panel or the ones that go to the fuse box or are they the same thing?
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From: Midwest. Aiming about mid-chest
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My civic 05 ex 5 speed has had an ac problem for sometime now and have not been able to figure out whats wrong.Any opinions would be appreciated. The symptoms that iam experiencing with the ac are:
1.The ac control button light to turn on and off(push), has had a change in polarization or when i turn the compressor on, the light is off and when its off the light is on.
2.The ac engages and disengages when in idle, but if i turn the ac on while in idle and start driving the ac does not want to disengage and my lines freeze over.
3. On really cold mornings before i go to school, once i turn the car on, the ac automatically engages and i cannot turn it off period and sometimes you hear like short circuit by the fuse box under the hood and the ac is engaging and disengaging like crazy and rpms rev up and down by about 100. Only when its cold outside which confuses me. When this happens i decide to disconnect the relay that controls the ac clutch and the ac clutch does disengage but the short circuit sound in the fuse box under the hood gets worse.im afraid my car will catch on fire
4.Last but not least on top of all that i realized that even when ac clutch does not want to disengage, it does not even cycle at the least either which causes my lines to freeze over.
So if anyone can get back at me for those 4 problems im having, i would really appreciate it. Its been driving me crazy.
1.The ac control button light to turn on and off(push), has had a change in polarization or when i turn the compressor on, the light is off and when its off the light is on.
2.The ac engages and disengages when in idle, but if i turn the ac on while in idle and start driving the ac does not want to disengage and my lines freeze over.
3. On really cold mornings before i go to school, once i turn the car on, the ac automatically engages and i cannot turn it off period and sometimes you hear like short circuit by the fuse box under the hood and the ac is engaging and disengaging like crazy and rpms rev up and down by about 100. Only when its cold outside which confuses me
. When this happens i decide to disconnect the relay that controls the ac clutch and the ac clutch does disengage but the short circuit sound in the fuse box under the hood gets worse.im afraid my car will catch on fire 4.Last but not least on top of all that i realized that even when ac clutch does not want to disengage, it does not even cycle at the least either which causes my lines to freeze over.
So if anyone can get back at me for those 4 problems im having, i would really appreciate it. Its been driving me crazy.
1) That's interesting. I haven't seen that one before. Are you positive that is what it does? Bad controller is the first thing I think of.
2) How low is the idle speed? The AC should disengage if the idle speed goes under about 600 rpm. A low idle speed will cause the AC to kick on and off repeatedly (kicks on-idle drops-kicks off-idle goes up-repeat) until you give it a little throttle, then it stays on and should cycle normally.
This could be a second problem, separate from the rest of this.
But the freeze up is not right at all.
The PCM controls the relay for the compressor clutch, so the relay is doing what it is told by the PCM.
The other clicking in the box is probably the 2 fan relays being turned on at the same time as the compressor. Also operated by the PCM.
A good scanner could give the data for AC request and AC operation as the PCM sees it. That would eliminate the PCM from the picture as a cause.
3) You got the front defroster on? The AC is supposed to run.
4) Freeze up is not right at all.
So far it all sounds like the heater control panel is probably bad (the chunk behind the 3 dials). Do the self test:
Fan switch OFF
Hold down the Recirculate and rear defrost buttons.
Turn the key on (don't start the engine). Let go of the buttons.
The lights on those 2 buttons come on
Recirc light goes off
AC light comes on
Self test starts. Let it do its thing.
AC light goes out when self test is over.
Now the Recirc light blinks out any codes.
If no codes stored, then no light.
Report back with this info.
Another idea:
When it is acting up, yank out the trim and unplug the connector behind the pushbuttons (I think it has about 10 wires in it), symptoms shouldn't change.
Then unplug the heater control panel (2 plugs).
Make sure everything that has to do with AC shuts off.
That eliminates the multiplex unit and some of the wiring, and leaves the control panel and all of its sensors and wiring as the likely cause.
When the morning is going to be cold and you know it will act up: yank out the control panel and take it in the house, keep it warm. Plug it in in the morning before it has time to get cold and see if it acts right, or at least different from what it would have done if it was really cold.
Got a buddy you can swap panels with just for testing?
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Yeah im positive that it does that for 1. Also i forgot to mention that since whenever the light(push) has to be on for the ac to be off, if i want to turn the fan off(*****) it causes the push button light to shut off thus also causing the ac to kick in. Its really weird.
The idle speed is about 600 so maybe that could be the reason for it kicking on and off but i still should be able to shut it off with the controller but i cannot(only in cold mornings). Umm as for the pcm i wouldnt know where to get it scanned in order to see if it is the ecu thats the cause. But if it was the ecu wouldnt my ac act up all the time and not just when its cold. Its been regular temperatures these past days now, and ac doesnt engage unless i turn the light off(push). Now the fact that if do engage it, and once i drive for about 5 minutes and it doesnt want to turn off, That confuses me.
Also i dont know if the defroster light being off means its on(push) because the ac light(push) button is messed up so i wouldnt know. but most likely my defroster is off when the light is off because ive been drving with the light off and the ac is off, only on the cold mornings it acts up.
As for the self test, could you explain a little more what that does? Ive never heard of this and i will try it out and tell you the results but im not sure what its doing though. But i will post back as soon as i get results. and i do not have a friend who i could swap parts for testing so i was thinking about buying a new control panel but on the morning it acts up i did disconnect the push button part from the panel and the ac clutch was still engaged so something else was giving it power unless it was the fan dials(*****)
The idle speed is about 600 so maybe that could be the reason for it kicking on and off but i still should be able to shut it off with the controller but i cannot(only in cold mornings). Umm as for the pcm i wouldnt know where to get it scanned in order to see if it is the ecu thats the cause. But if it was the ecu wouldnt my ac act up all the time and not just when its cold. Its been regular temperatures these past days now, and ac doesnt engage unless i turn the light off(push). Now the fact that if do engage it, and once i drive for about 5 minutes and it doesnt want to turn off, That confuses me.
Also i dont know if the defroster light being off means its on(push) because the ac light(push) button is messed up so i wouldnt know. but most likely my defroster is off when the light is off because ive been drving with the light off and the ac is off, only on the cold mornings it acts up.
As for the self test, could you explain a little more what that does? Ive never heard of this and i will try it out and tell you the results but im not sure what its doing though. But i will post back as soon as i get results. and i do not have a friend who i could swap parts for testing so i was thinking about buying a new control panel but on the morning it acts up i did disconnect the push button part from the panel and the ac clutch was still engaged so something else was giving it power unless it was the fan dials(*****)
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i tried the self test and it didnt do exactyle what you stated above. First the two lights that i held came off the recirculate and defroster then the defroster light came on instead and i waited for like 5 minutes and it never came back off oh and the ac light never came on. I dont know if this is because the controller is messed up or what.
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Yeah im positive that it does that for 1. Also i forgot to mention that since whenever the light(push) has to be on for the ac to be off, if i want to turn the fan off(*****) it causes the push button light to shut off thus also causing the ac to kick in. Its really weird.
The idle speed is about 600 so maybe that could be the reason for it kicking on and off but i still should be able to shut it off with the controller but i cannot(only in cold mornings). Umm as for the pcm i wouldnt know where to get it scanned in order to see if it is the ecu thats the cause. But if it was the ecu wouldnt my ac act up all the time and not just when its cold. Its been regular temperatures these past days now, and ac doesnt engage unless i turn the light off(push). Now the fact that if do engage it, and once i drive for about 5 minutes and it doesnt want to turn off, That confuses me.
Also i dont know if the defroster light being off means its on(push) because the ac light(push) button is messed up so i wouldnt know. but most likely my defroster is off when the light is off because ive been drving with the light off and the ac is off, only on the cold mornings it acts up.
As for the self test, could you explain a little more what that does? Ive never heard of this and i will try it out and tell you the results but im not sure what its doing though. But i will post back as soon as i get results. and i do not have a friend who i could swap parts for testing so i was thinking about buying a new control panel but on the morning it acts up i did disconnect the push button part from the panel and the ac clutch was still engaged so something else was giving it power unless it was the fan dials(*****)
The idle speed is about 600 so maybe that could be the reason for it kicking on and off but i still should be able to shut it off with the controller but i cannot(only in cold mornings). Umm as for the pcm i wouldnt know where to get it scanned in order to see if it is the ecu thats the cause. But if it was the ecu wouldnt my ac act up all the time and not just when its cold. Its been regular temperatures these past days now, and ac doesnt engage unless i turn the light off(push). Now the fact that if do engage it, and once i drive for about 5 minutes and it doesnt want to turn off, That confuses me.
Also i dont know if the defroster light being off means its on(push) because the ac light(push) button is messed up so i wouldnt know. but most likely my defroster is off when the light is off because ive been drving with the light off and the ac is off, only on the cold mornings it acts up.
As for the self test, could you explain a little more what that does? Ive never heard of this and i will try it out and tell you the results but im not sure what its doing though. But i will post back as soon as i get results. and i do not have a friend who i could swap parts for testing so i was thinking about buying a new control panel but on the morning it acts up i did disconnect the push button part from the panel and the ac clutch was still engaged so something else was giving it power unless it was the fan dials(*****)
Reread what I said to unplug. If you only unplugged the button set, nothing should change.
Unplug the 2 connectors behind the *****. The AC compressor should shut down.
See if that is what actually happens.
If the AC compressor shuts off at this point, the scanner isn't necessary for further checking.
The self test is just that. A self diagnosis mode for the HVAC controller. Accessed through a series of button commands, and the results are displayed on the lights by flashing a numeric code. See the other post.
Just more information for me at this point.
Any information gleaned from it may or may not be of any value at this point, but worth checking.
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i tried the self test and it didnt do exactyle what you stated above. First the two lights that i held came off the recirculate and defroster then the defroster light came on instead and i waited for like 5 minutes and it never came back off oh and the ac light never came on. I dont know if this is because the controller is messed up or what.
I thought maybe there could be some info from that if it gave up any codes, but a bad control unit might not be able to check its own systems, or it can't be trusted if it did.
I still want to make sure that unplugging the other 2 connectors makes the AC shut off before going any further.
At this point I would be trying to swap one from another car to make absolutely sure that a new one is going to fix it, or start looking for a good used controller and panel complete at a junkyard, or pony up for a brand new one. Note that these things DO go bad, so a used one might be an "iffy" choice, you take your chances.
Item #2 in this link, if I picked the right car out of the list: http://www.hondaautomotiveparts.com/...HEATER+CONTROL
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ok i did that, i unplugged both of the ***** connectors and everything did shut down. The ac clutch completely turned off and so does that mean its the controller thats bad then. Oh and if i were to buy the ac heater assembly(*****), should i get just that or the whole panel, because i do have an aftermarket stereo :/ but anyways and should i buy it from ebay cause they go around for like 40 or 50 bucks and that website you suggested is almost 200 :s and by the way im a college student so money is pretty tight. ONe more question, as a test, when im drving with the ac on and it does not want to shut off anymore, should i disconnect the **** assembly there and see if it shuts off, and should that truly let me know its the controller.
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....ok i did that, i unplugged both of the ***** connectors and everything did shut down. The ac clutch completely turned off and so does that mean its the controller thats bad then.
Coupled with the fact that it can't properly control the light in the AC button, I'd say that's the most likely suspect.
..... Oh and if i were to buy the ac heater assembly(*****), should i get just that or the whole panel, because i do have an aftermarket stereo :/
The part that I pointed out is the suspected bad item. That is what needs replaced, no matter how much of the rest of the panel you happen to obtain or replace.
Gee. Now that you mention that, I hope nobody hacked into the HVAC wiring while cramming the radio in there.
.....but anyways and should i buy it from ebay cause they go around for like 40 or 50 bucks and that website you suggested is almost 200 :s and by the way im a college student so money is pretty tight.
I linked a dealer online catalog because it has the correct parts in the picture, and they have the correct parts available. Period. (I can't link the actual catalog I use.)
Your funding really isn't any of my concern. Ebay? Pay your money, take your chances.
College, huh? Learn that the cheapest people often spend the most.
....ONe more question, as a test, when im drving with the ac on and it does not want to shut off anymore, should i disconnect the **** assembly there and see if it shuts off,
Yes. Unplug the 2 connectors from the back of the box where the ***** are.
.....and should that truly let me know its the controller.
Not necessarily. But it is the most likely culprit.
At this point, a whole bunch of the car is eliminated because of how certain things are working, leaving only the heater control unit and a bunch of the HVAC input components and wiring as possible causes of your complaint.
Are you studying electrical engineering? Got a DVOM? I can walk you through individual electrical testing of all the components connected to the heater control unit if you really want.
There are a lot of areas and items involved between the button you push and the compressor that engages and runs.
More than meets the eye.
I usually have a logical plan with diagnosis. You may not understand it, but there is logic and reason in my mind.
But
I have to rely on your info and answers since I can't see/hear/touch/whisper/test/feel/whatever/voodoo/diagnose the car myself. I have no idea what your abilities are, nor what tools you have available.
Accurate and complete descriptions of all problems and symptoms are critical.
No matter if YOU understand why, I may see a relationship between many symptoms and see a common denominator.
The next question depends on the previous answer.
Coupled with the fact that it can't properly control the light in the AC button, I'd say that's the most likely suspect.
..... Oh and if i were to buy the ac heater assembly(*****), should i get just that or the whole panel, because i do have an aftermarket stereo :/
The part that I pointed out is the suspected bad item. That is what needs replaced, no matter how much of the rest of the panel you happen to obtain or replace.
Gee. Now that you mention that, I hope nobody hacked into the HVAC wiring while cramming the radio in there.
.....but anyways and should i buy it from ebay cause they go around for like 40 or 50 bucks and that website you suggested is almost 200 :s and by the way im a college student so money is pretty tight.
I linked a dealer online catalog because it has the correct parts in the picture, and they have the correct parts available. Period. (I can't link the actual catalog I use.)
Your funding really isn't any of my concern. Ebay? Pay your money, take your chances.
College, huh? Learn that the cheapest people often spend the most.
....ONe more question, as a test, when im drving with the ac on and it does not want to shut off anymore, should i disconnect the **** assembly there and see if it shuts off,
Yes. Unplug the 2 connectors from the back of the box where the ***** are.
.....and should that truly let me know its the controller.
Not necessarily. But it is the most likely culprit.
At this point, a whole bunch of the car is eliminated because of how certain things are working, leaving only the heater control unit and a bunch of the HVAC input components and wiring as possible causes of your complaint.
Are you studying electrical engineering? Got a DVOM? I can walk you through individual electrical testing of all the components connected to the heater control unit if you really want.
There are a lot of areas and items involved between the button you push and the compressor that engages and runs.
More than meets the eye.
I usually have a logical plan with diagnosis. You may not understand it, but there is logic and reason in my mind.
But
I have to rely on your info and answers since I can't see/hear/touch/whisper/test/feel/whatever/voodoo/diagnose the car myself. I have no idea what your abilities are, nor what tools you have available.
Accurate and complete descriptions of all problems and symptoms are critical.
No matter if YOU understand why, I may see a relationship between many symptoms and see a common denominator.
The next question depends on the previous answer.
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my major is mechanical engineering(1st semester 2nd year). I mean i wouldnt mind you walking me through but i do not have a digital vom and if were to get one, how much would they run by. Also what do you mean by hacked the wiring in the hvac, do the wires in the ac system have anything to do with the radio... I wish i had all the tools and abilities neccesary first things first though, i will change the heater control assembly before proceeding. Probably get on of those pick and pulls, they come with warranty 
first things first though, i will change the heater control assembly before proceeding. Probably get on of those pick and pulls, they come with warranty If you think a good mechanic is expensive, try hiring a bad one
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my major is mechanical engineering(1st semester 2nd year). I mean i wouldnt mind you walking me through but i do not have a digital vom and if were to get one, how much would they run by. Also what do you mean by hacked the wiring in the hvac, do the wires in the ac system have anything to do with the radio... I wish i had all the tools and abilities neccesary first things first though, i will change the heater control assembly before proceeding. Probably get on of those pick and pulls, they come with warranty
first things first though, i will change the heater control assembly before proceeding. Probably get on of those pick and pulls, they come with warranty My main DVOM was around $400 several years ago (it's a nice one). I also use the $20 meters from Sears. Each has its purposes.
Hacked wiring is always a possibility whenever a DIY'er does a stereo. No, the stereo wiring has nothing to do with the HVAC, but you wouldn't believe the mistakes I have seen over the years caused by stereo, cellphone, accessory, and other installations. Even from "professional" installers. All it takes is connecting to a wrong wire or slashing a few with a razor knife, or having wires rub through the insulation against a sharp new radio bracket.....
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well lets hope its not a wiring problem and just the heater control. And yeah i wish i was more experienced in this sort of stuff, hopefully one day i will be. Im planning on getting the heater control to let you know the results real soon. Its just that this is final exam week and being studying so have not gotten around to it. Oh and youve been real helpful, without you i would of never known where to start in fixing my ac.
Well ill post up the results soon and if it does not fix the problem or maybe it fixes some of the problems, then hopefully you still wanna help me out
one last thing, as for the clutch not cycling in the compressor, would you think its the clutch thats messed up or do you think that bad wiring or bad heater control could cause that as well. I know i ask to much questions sorry but i would like to have an idea thanx
Well ill post up the results soon and if it does not fix the problem or maybe it fixes some of the problems, then hopefully you still wanna help me out
one last thing, as for the clutch not cycling in the compressor, would you think its the clutch thats messed up or do you think that bad wiring or bad heater control could cause that as well. I know i ask to much questions sorry but i would like to have an idea thanx
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one last thing, as for the clutch not cycling in the compressor, would you think its the clutch thats messed up or do you think that bad wiring or bad heater control could cause that as well. I know i ask to much questions sorry but i would like to have an idea thanx
How do you know that?
(Because I don't know it. I'm relying on YOUR answers. Remember, every question depends on the last answer.)
You have a lot to learn, slim. Learn how to learn. I bet the answer you seek has already been typed out in this thread, if you read and comprehend it all.
There aren't abstracts in engineering, right? Everything is solid, exact, concrete, no room for variations, right? A problem is supposed to only have a finite amount of possible solutions?
(This is why I love fixing machinery instead of people: A finite number of solutions to any problem. People have far too many variables. I hate people.)
If you are going into any field of engineering then you ought to learn how to reason logically. That would mean (to me, in this case), learning how this entire mess is supposed to work, then reasoning out your own answer to the question. Test your theory, and re-evaluate and modify your theory if necessary.
In order to figure out what's broke, you gotta know how it was supposed to work in the first place. Or be able to reason it out based on basics and principles you already know.
Does the clutch work? How do you know?
Do you know what it is supposed to do?
Do you know what "cycling" is?
Do you know what the job and purpose of the clutch is?
Do you know what controls the clutch?
Do you know what determines the operation of the clutch?
Do you know why it is this way?
Can you figure out why I didn't say anything about replacing the compressor clutch?
Lets see how much you can understand about this before I answer.
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The clutch works because when i turn on the ac, when i look under the hood, the clutch is spinning and youc an hear it engage, and it blows cool air.
well to my understanding, the clutch is suppose is suppose to power the compressor by a belt attached to the engine and at the same time it has to cycle in order to keep the system from freezing or as a way of regulating temperature and not keep the compressor running non stop
Cycling is when the clutch turns off temporarily and then turns back on etc
the job of the clutch is to power the compressor and the purpose of it is to provide energy to the compressor im not sure
The clutch is controlled by the relay in the fuse box under the hood which is controlled by the hvac controller not sure again
as for what determines the operation of the clutch im not sure i would think its the relay but the ecu might have a role in it not sure on this one either
as for the last question, why it all works like this, all i can say is maybe because its the most efficient way and tends to have less errors or malfunctions then other ways not sure again.
and noe maybe you can help understand why you didnt say anything about replacing the compressor clutch and i think its because it all leads back to the hvac controller but help me out here
well to my understanding, the clutch is suppose is suppose to power the compressor by a belt attached to the engine and at the same time it has to cycle in order to keep the system from freezing or as a way of regulating temperature and not keep the compressor running non stop
Cycling is when the clutch turns off temporarily and then turns back on etc
the job of the clutch is to power the compressor and the purpose of it is to provide energy to the compressor im not sure
The clutch is controlled by the relay in the fuse box under the hood which is controlled by the hvac controller not sure again
as for what determines the operation of the clutch im not sure i would think its the relay but the ecu might have a role in it not sure on this one either
as for the last question, why it all works like this, all i can say is maybe because its the most efficient way and tends to have less errors or malfunctions then other ways
not sure again. and noe maybe you can help understand why you didnt say anything about replacing the compressor clutch and i think its because it all leads back to the hvac controller but help me out here
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Allright! You're typing almost as much as I have been.
Most of this is off the top of my head, no reference materials...
The clutch works because when i turn on the ac, when i look under the hood, the clutch is spinning and youc an hear it engage, and it blows cool air.
Yes
well to my understanding, the clutch is suppose is suppose to power the compressor by a belt attached to the engine and at the same time it has to cycle in order to keep the system from freezing or as a way of regulating temperature and not keep the compressor running non stop
Yes
Cycling is when the clutch turns off temporarily and then turns back on etc
Yes
the job of the clutch is to power the compressor and the purpose of it is to provide energy to the compressor im not sure
Yeah. The clutch couples and uncouples the belt driven pulley to the driveshaft of the compressor.
There are direct drive compressors out there too. No clutch. The compressor is driven the whole time the engine is running. That's another ball game. Freon flow in controlled within the compressor itself.
The clutch is controlled by the relay in the fuse box under the hood which is controlled by the hvac controller not sure again
Close enough.
as for what determines the operation of the clutch im not sure i would think its the relay but the ecu might have a role in it not sure on this one either
Sort of.
as for the last question, why it all works like this, all i can say is maybe because its the most efficient way and tends to have less errors or malfunctions then other ways not sure again.
Nah, that's just one way to make it work. There are other ways that AC systems can be controlled.
All refrigeration systems operate on the same principles no matter if it is in a car or your dorm fridge or the walk-in cooler at the tavern...Evaporation and condensation.
The methods of operation vary. Controls vary. Etc. But the principles are always the same.
That whole thing was to see how much you understand about this AC system. You seemed to keep asking the same things over and over and I was getting frustrated. Sorry about that.
and noe maybe you can help understand why you didnt say anything about replacing the compressor clutch and i think its because it all leads back to the hvac controller but help me out here
Yes.
I didn't say anything about replacing the clutch because there is nothing wrong with it.
In a nutshell:
The clutch engages and disengages. It is good.
It drives the compressor. Good.
The system cools well when the clutch is engaged. It is good, plenty of freon.
The system itself works fine.....until
The system freezes when the compressor can't be cycled off. Problem. Control problem, specifically.
Clutch is switched on and off by the relay.
The relay is controlled by the PCM.
The PCM got a request from the MICU.
The MICU got a request from the HVAC controls.
The PCM has control of the clutch and radiator fans, depending on engine operating conditions. Idle too slow? AC shuts down. Wide open throttle? AC shuts down. Engine overheating? AC shuts down.
The MICU (multiplex system) has the ability to shut the AC system off if refrigerant pressures are too high or too low.
The HVAC controller (when it works properly) looks at what you asked of it (in this case the AC button) and watches the temp of the evaporator core when the AC is running. (It also looks for the blower fan to run and will shut off the AC if the fan does not run, but that's not important right now.)
The evap temp sensor is used by the HVAC controller to regulate the cycling of the compressor when the system is working properly. The system is supposed to cycle the compressor OFF when the evap core gets down to about 34-36 deg. F, so it doesn't turn into a big ice cube. Will kick the compressor back on about 6 degrees or so above the shutoff temp. Vent temps could be around 38-60 depending on several other factors like system pressures, humidity and the temps of the intake air. If there is at least a 40 degree drop across the evaporator core, the system is probably working decent.
On a 110+ degree day, vent temps of 55+ can be perfectly acceptable depending on conditions.
On a 70 degree day I would expect it to cycle off and on around between 38 and 44ish. Give or take a little bit. Some cycle at a little bit higher temps than that too, like 42-46.
Now...
You unplugged the HVAC controller and the AC system shut down because the MICU lost its request, and therefore the PCM lost its request.
The PCM and MICU are doing what they are told.
The problem MUST be on the HVAC end of the circuit.
Divide and conquer.
See the logic there?
(It didn't have to be the HVAC controller, it could have been the temperature sensor, maybe something else, but it HAS to be on this end of the circuit. BUT in your case you have an obvious issue with the lights and some totally wrong operations-- that just about almost can't be anything BUT the controller itself.)
If the AC did NOT shut down when you unplug the HVAC controls, then I would have gone a different direction.
This entire troubleshooting theory only applies to this particular system and these specific controls.
The diagnostic approach changes with every different system.
"The answer to this last question will determine whether you are drunk or not. Was Mickey Mouse a cat or dog?"
Most of this is off the top of my head, no reference materials...
The clutch works because when i turn on the ac, when i look under the hood, the clutch is spinning and youc an hear it engage, and it blows cool air.
Yes
well to my understanding, the clutch is suppose is suppose to power the compressor by a belt attached to the engine and at the same time it has to cycle in order to keep the system from freezing or as a way of regulating temperature and not keep the compressor running non stop
Yes
Cycling is when the clutch turns off temporarily and then turns back on etc
Yes
the job of the clutch is to power the compressor and the purpose of it is to provide energy to the compressor im not sure
Yeah. The clutch couples and uncouples the belt driven pulley to the driveshaft of the compressor.
There are direct drive compressors out there too. No clutch. The compressor is driven the whole time the engine is running. That's another ball game. Freon flow in controlled within the compressor itself.
The clutch is controlled by the relay in the fuse box under the hood which is controlled by the hvac controller not sure again
Close enough.
as for what determines the operation of the clutch im not sure i would think its the relay but the ecu might have a role in it not sure on this one either
Sort of.
as for the last question, why it all works like this, all i can say is maybe because its the most efficient way and tends to have less errors or malfunctions then other ways
not sure again. Nah, that's just one way to make it work. There are other ways that AC systems can be controlled.
All refrigeration systems operate on the same principles no matter if it is in a car or your dorm fridge or the walk-in cooler at the tavern...Evaporation and condensation.
The methods of operation vary. Controls vary. Etc. But the principles are always the same.
That whole thing was to see how much you understand about this AC system. You seemed to keep asking the same things over and over and I was getting frustrated. Sorry about that.
and noe maybe you can help understand why you didnt say anything about replacing the compressor clutch and i think its because it all leads back to the hvac controller but help me out here
Yes.
I didn't say anything about replacing the clutch because there is nothing wrong with it.
In a nutshell:
The clutch engages and disengages. It is good.
It drives the compressor. Good.
The system cools well when the clutch is engaged. It is good, plenty of freon.
The system itself works fine.....until
The system freezes when the compressor can't be cycled off. Problem. Control problem, specifically.
Clutch is switched on and off by the relay.
The relay is controlled by the PCM.
The PCM got a request from the MICU.
The MICU got a request from the HVAC controls.
The PCM has control of the clutch and radiator fans, depending on engine operating conditions. Idle too slow? AC shuts down. Wide open throttle? AC shuts down. Engine overheating? AC shuts down.
The MICU (multiplex system) has the ability to shut the AC system off if refrigerant pressures are too high or too low.
The HVAC controller (when it works properly) looks at what you asked of it (in this case the AC button) and watches the temp of the evaporator core when the AC is running. (It also looks for the blower fan to run and will shut off the AC if the fan does not run, but that's not important right now.)
The evap temp sensor is used by the HVAC controller to regulate the cycling of the compressor when the system is working properly. The system is supposed to cycle the compressor OFF when the evap core gets down to about 34-36 deg. F, so it doesn't turn into a big ice cube. Will kick the compressor back on about 6 degrees or so above the shutoff temp. Vent temps could be around 38-60 depending on several other factors like system pressures, humidity and the temps of the intake air. If there is at least a 40 degree drop across the evaporator core, the system is probably working decent.
On a 110+ degree day, vent temps of 55+ can be perfectly acceptable depending on conditions.
On a 70 degree day I would expect it to cycle off and on around between 38 and 44ish. Give or take a little bit. Some cycle at a little bit higher temps than that too, like 42-46.
Now...
You unplugged the HVAC controller and the AC system shut down because the MICU lost its request, and therefore the PCM lost its request.
The PCM and MICU are doing what they are told.
The problem MUST be on the HVAC end of the circuit.
Divide and conquer.
See the logic there?
(It didn't have to be the HVAC controller, it could have been the temperature sensor, maybe something else, but it HAS to be on this end of the circuit. BUT in your case you have an obvious issue with the lights and some totally wrong operations-- that just about almost can't be anything BUT the controller itself.)
If the AC did NOT shut down when you unplug the HVAC controls, then I would have gone a different direction.
This entire troubleshooting theory only applies to this particular system and these specific controls.
The diagnostic approach changes with every different system.
"The answer to this last question will determine whether you are drunk or not. Was Mickey Mouse a cat or dog?"
Thread Starter
Registered!!
Joined: Dec 2011
Posts: 25
Likes: 0
Rep Power: 0 Re: Ac problem
Well i changed the ac controller that arrived yesterday and IT DID THE TRICK!!! Man my ac was working like the gods lol. Man i just want to say thanx for all your help, i literally went 5 months with the thing messed up and that is why i decided to join the civic forums. Yo you are the best, and you also helped me learn something about how ac systems work in automobiles. WEll hopefully you can help me out with anyther problems i run intro thanx alot!!!
If you think a good mechanic is expensive, try hiring a bad one
Joined: Dec 2011
Posts: 32,017
Likes: 256
From: Midwest. Aiming about mid-chest
Rep Power: 518 Re: Ac problem
You're welcome.
My fingers hurt from typing all that out.
Glad you learned something.
I am NOT a teacher, I don't have the patience for it in real life. LOL
You didn't answer this one: "The answer to this last question will determine whether you are drunk or not. Was Mickey Mouse a cat or dog?"
My fingers hurt from typing all that out.
Glad you learned something.
I am NOT a teacher, I don't have the patience for it in real life. LOL
You didn't answer this one: "The answer to this last question will determine whether you are drunk or not. Was Mickey Mouse a cat or dog?"
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