Ohmster

Hey guys,
My 08 Civic is a beautiful car, love it to death. Always had ice cold air conditioning. It stopped working about a week ago, compressor would come on for about a minute, then clutch would release compressor, never kicks in again. I checked the refrigerant, I lowered it a bit on the low side from 90 to about 75 PSI. But that compressor will not turn on again. I thin there are two sensors, one on the compressor and one at the receiver/dryer, somewhere in the passenger compartment. Also a relay for A/C compressor in the under hood relay/fuse box. I swapped out the relay, nothing. Don't know how to check the other sensors, although I am an electronic tech and know how to use a digital meter.

I heard the best place to start tracking this problem is that the relay, but what wires to check, how to get at them, and how to figure out what is bad. I hope that it is not the computer. No other problems with car, other than passenger mirror no longer adjusts with motor. I cannot find a service manual or diagrams for this 2008 Civic anywhere and am too poor right now to buy one. Somebody help me please. Links, diagrams, advice, pictures, anything would help a lot. Thanks guys!

ezone

Probably the wrong move there. I bet a nickel that now there is not enough freon in it.

IF nobody ever added freon and got too much in it, how would the pressure ever be too high?





Ok, answer this: When you turn on the AC system, what DOES happen?

Does the inside blower fan work?
Do the radiator fans come on?



Do you know how a simple 4 terminal relay works?

matt3124

Agreed. I'd also evacuate the system, recharge it to specs (use the stuff with that dye in it to be able to search for leaks if it quits again). Had this same prob a few years back on my Ford Exploder and it turned out to be a bad o-ring where the line attached to the compressor. It would leak out after a week. Two recharges and $150 and the problem was a 50 cent o-ring, but at least not a new compressor. Could be sensors or relays as you mentioned, but I'd check for leaks before doing anything else.

Ohmster

The gauge and can is marked. There is an ambient temperature chart for PSI at the local ambient temperature. When I hooked up the gauge, it was way over into the red, somewhere over 120.

Because I thought it stopped from a freon leak and my buddy dumped a can into the system last week. It ran nice and cold but I did not leave it run for long. When I went out ½ later, the compressor would not come on at all. So Jerry added another ½ can, still no compressor, and we stopped putting in refrigerant.


Yes,
Well, there are two side by side radiator fans and they both run when engine is on, regardless of the A/C.

• Cabin blower fan comes on unless set to zero.
• Green LED lights on dashboard for A/C., Maximum, and amber light for recirculating cabin air.
• A/C Compressor clutch does not engage, middle of the compressor pulley does not turn, although it would come on for a minute or so, then go off. When it does engage the compressor, the air coming from cabin vents is VERY cold. Now the compressor clutch never engages at all anymore.

Of course, I said I am an electronic tech. I have replaced, tested, and even opened and fixed relays like that in an emergency. Usually the contacts burn from arcing, sometimes small magnets are glued to the outside case to "blow out the arc" and preserve the contacts. Sometimes the coil opens up, rendering it useless. These relays use two pins for the magnetic coil. Then you have what amounts to a toggle switch that is activated by the magnetic coil turning on. You can have 2 additional connector pins for SPST switch, 3 additional connector pins for SPDT switch, or more multiples of the same. Since this relay is 4 pins, two are for the coil and the other two are to switch on the compressor.

Ohmster

I had this done at the dealer a little over a year ago. They evacuated the system, introduced dye, ran it for a while, and on the low pressure hose, right at the fill cap, you could see the dye sprayed all over where the fill cap went. The dealer replaced the hose, cabin filter, and outside are door actuator. Wanted $600 for the repair, bargained it down to $500, Ice cold air ever since until now when the compressor started dropping out and now will not come on again. When it came on last, less than a week ago, it was ice cold. There is more than enough refrigerant in the system. I am dead broke while waiting for my disability claim to be processed, it could take up to two more months. At that time, I will have the entire thing checked from top to bottom and even get the 95K maintenance done. I love my Honda Civic and miss the fact that the passenger mirror does not work by driver door control anymore and will have that fixed too. Until then, I need cold air, this is Florida and the heat and humidity will kill you down here!

Ohmster

I did answer all of your questions honestly and I really need and appreciate your help. Thank you for taking an interest, fellows.

I will fix it proper when my check comes, but that could be 30-90 days. If my compressor and refrigerant is all good, and I know it is, then it is either a sensor, relay (Checked it last night, NOT a bad relay) but finding the relay is difficult without diagrams and current '08 Civic repair information. Could be sensor, relay, ECU (Oh God, I cannot afford a new computer!), wiring, fuse, or what else and where are these items, how to get to them, and how to test them?

I would dare to jump out a bad sensor for a VERY short time, love this car too much to "Rube Goldberg" this car and not repair things proper. But I would jump a sensor for a short time if need be. Help me, guys! I did not see email notification so I did not think to look here until today.

~Ohmster
ohmster five nine at g mail dot com

ezone

You cannot jumper a pressure transducer. Ain't gonna work...


You didn't mention that someone already dicked with the freon (R134a) in your first post.

These systems are so small there is very little room for error. A mere couple ounces over or under spec can really screw up the system and makes it horribly inefficient.




The temperature of the system in an engine compartment is not the same temp as ambient if it has been sitting in the sun, much like the interior of the car after it has been sitting in the sun.
If the engine has been running and is hot, the AC system is not at ambient temp either. Static pressures will be very elevated.

Static system pressure is no way to evaluate the amount of freon in a system. Period. All it can really tell is that there is SOME freon in the system.

Reading the system pressures both high and low sides-- while in operation-- is the way to go, and you can't do that with only a low side gauge.

But right now, you say it's cold when it works so we'll leave it alone.

Problem: They should NOT run until the coolant temperature is high enough to turn them on, or when the AC system turns them on.

You have a problem here, unless your story needs more clarification..


I need to know if the AC system is commanding the radiator fans on, and if they are still running when the compressor quits. I'm looking at whether or not the thermal protector is opening, pressure transducer, coolant temp sensor, or something else is shutting the system down, or if the problem is likely isolated to the compressor clutch and its controls.

If the fans run ALL the time, then you cannot evaluate and tell me what I need to know.
¿Comprende?

Um, is the radiator full? If the radiator is low and the engine is overheating, the AC is disabled by the PCM.




If the problem is caused by MICU, PCM, wiring and sensors, you probably aren't going to do much troubleshooting without a real scanner. (Is the PCM receiving the AC request from the MICU? Is the PCM turning on the clutch relay?)
If it's related to the compressor controls, you can probably fix it.


You just wrote a whole lot about what you know about relays. Bla bla bla. Now apply it.

Find the compressor clutch relay in the underhood fusebox. It's probably only labeled with a single snowflake symbol.

I'm pretty sure the AC clutch relay is closest to the fuse labeled #5 here.

Far too simple, you should kick yourself: When the system quits, go tap on the clutch relay. Does the AC come back on? You should know what to do.

Simple but dirty: Does the compressor clutch still receive 12v+ while it is inoperative?

Or clean but more time consuming:
Clutch relay has 4 pins:
2- contacts, terminals 1 and 2,
2-electromagnetic coil, terminals 3 and 4.

3&4 powered and grounded? The relay is being commanded on or not. Your answer?


Contacts:
What is the resistance of the clutch field coil, as measured at the clutch relay socket?

Is there B+ at the other terminal in the socket?

Jumper them: does the compressor clutch engage?

Plug the relay back in and start the engine, and let the AC operate for the one minute it can run until the AC quits on its own. Can you still do the above jumper and get the clutch to engage?

ezone

There IS a spot to select email notifications too. Somewhere around here.

USER CP in the upper left,

or at the bottom of each reply window area after you select "go advanced" button, look for this
Thread Subscription

Notification Type:

Ohmster

Alright everybody, I got the A/C fixed. It is 80° outside and I went for a drive, freezing my butt off. I have a really good digital thermometer that I use for deep frying, but it measures anything, instantly. I put it in the A/C vent and drove around, it went into the forties! So this thing is fixed.

What I did:

• Gathered everything I could find on 2008 Honda Civic so far as electrical diagrams for heat and A/C, illustrations showing where everything is, text explaining how it works, and with that, a digital meter, and some daylight hours, I got it done.
• Setup digital meter, tablet PC with all images, diagrams, and instructions. Sure beats having to print all that stuff out and you can zoom in at any point. Checked 3 wire plug to compressor. Blue/Red to ground for coil, reads 3Ω, that is good, checked Blue and Blue/White wire for thermal protector, that read like .5Ω, good again. Not the problem.
• Pulled relay from under the hood, examined it, looks okay, swapped it with same relay from another circuit, made no difference, relay is good.
• Checked fuse #20 under hood fuse box, 7.5 Amp. Looks good, pulled it, checked good. Put it back in firmly and compressor clutch kicked right in. I could not believe it. Let it run for quite a while, solid as a rock. Replaced fuse anyway, almost 99.9% of fuses show bad by sight or meter, every once in a while, one is intermittent of does not seat properly. These things drive you mad trying to find them, so if you even suspect such a thing, replace the fuse, it costs less than one dollar.
• Drove around all afternoon with digital thermometer in vent, readings in the 40° zone. This is really fixed.
• I already knew the compressor was good and the refrigerant was not low, so it left only the electrical to check and I am good at electrical, if I can get the right diagrams. Had this been the ECU or car computer, I really would have been screwed. That thing must cost over $500 and the dealer labor would have put me into bankruptcy.

Wanted to say thanks everybody for caring and offering to help. Out of three Honda forums, this is the only one where somebody did reply. I won't forget it.


Oh, I will add some pictures and the zip file of all the diagrams and help I could find for working on a 2008 Honda Civic A/C unit. Hope it helps someone. Oh crud, the zip file is too big to attache. Anyone want or need it, get it here.

2008 Honda Civic A/C Diagrams

Caroldell1

My air condition stopped working, I replaced the relay under the hood started to blow air then stopped When I turned the **** for air I get nothing no air was blowing.
So I replace the Blower motor and the Resistor, after I did that the A/C is blowing hot air and when I try to shut it off on my dash it won't shut off just keeps blowing hot
air. Do you think I should replace the relays again. Can you help me with my problem. I live in Florida and very hot here. Please email asap of what you think my
problem is.

Gregomatic

Hey guys, I just wanted to take a moment to say how much I appreciate you all. THIS quote along with ezone's suggestions and diagram gave me EXACTLY what I needed to start troubleshooting my 07', with it's AC problem almost mirroring the details in this post. I'll post back after testing and report what I find. Thanks a bajillion!
Grego~

sdraza1

This might help