jagscivic

2003 Civic LX
Need some help. I went though the entire service repair manual trying to figure this out. The A/c clutch does not turn on. I took it to a repair shop and the guy used the machine and evacuated and recharged it. I then went through the electrical circuit. Step by step
1. If i jump relays, the AC clicks on and its cold air.
2. I grounded the RED wire going into the ECM and the AC clicks on.
3. I swapped in a new ECM (had to reflash) and that still didn't fix the problem.
4. I grounded the BLU/WHT wire on the back of the Multiplex and the AC clicked on.
5. I then jumped the pressure switch and it didnt click on.

The repair manual states the AC pressure switch has a Blue wire that goes to the Heater control panel (checked and it had continuity to heater pin 4). The repair manaul says the other wire on the pressure switch should be BLU/WHT and goes to the Multiplex, but on my car it as a RED wire and it went to another plug mounted to the fan assembly. The RED wire has no continuity to the BLU/WHT on the back of the Multiplex like the wiring diagram shows. I"m confused why is that?

I tried to jump the red wire to the BLU/WHT and the AC still didn't click on.

I also have a new issue, it wasn't there before I took it to the shop, but the A/C & Rear defrogger & Recirrculation push button LED does not light up, but the buttons still work. BAD GROUND MAYBE?

Could the heater panel assembly have a bad ground?

I'm very frustrated. What else could I try? I hope someone could give me some advice.

jagscivic

Also the blower motor and heater control panel switches all work.

ezone

4. I grounded the BLU/WHT wire on the back of the Multiplex and the AC clicked on.
Good.

5. I then jumped the pressure switch and it didnt click on.

Correct. Jumper does nothing because switch was already closed, as long as pressure is sufficient.

The repair manual states the AC pressure switch has a Blue wire that goes to the Heater control panel (checked and it had continuity to heater pin 4). The repair manaul says the other wire on the pressure switch should be BLU/WHT and goes to the Multiplex, but on my car it as a RED wire and it went to another plug mounted to the fan assembly. The RED wire has no continuity to the BLU/WHT on the back of the Multiplex like the wiring diagram shows.



FIRST
I would check the thermal protector for continuity. 2 red wires in the connector for the compressor clutch.
01 has no thermal protector. 02-05 do have it.
EDIT: it is there, but wired differently.
The thermal protector is wired between the pressure switch and the multiplex unit.

I"m confused why is that?

I'm only confused by reading your post. I was fine with wiring diagrams.

Your book is trying to cover more than just your car.





I tried to jump the red wire to the BLU/WHT and the AC still didn't click on.

Ground it. See if the compressor comes on.

In a nutshell: At step 4 where you grounded the blu/wht at the MICU was great, but you needed to work up the wire and keep grounding it to see where it stopped working.
The MICU can operate the system if it gets the ground signal on the blu/wht wire, so....

If you ground it at the pressure switch (red wire) and the comp does NOT kick on, then the thermal protector is likely open. Go to its connector and check it.

I may have just gone right to terminal A4 at the HVAC controller, and MEASURE for a ground signal when the ac is kicked on (If it supplies a ground, the controller is probably ok). Then ground terminal A4 to make sure it can kick on (is the rest of the system ok?).

A wiring diagram is valuable.





I also have a new issue, it wasn't there before I took it to the shop, but the A/C & Rear defrogger & Recirrculation push button LED does not light up, but the buttons still work. BAD GROUND MAYBE?

Doubt it.

What is more odd is that this is a brand new issue since someone else touched it. These HVAC controllers go bad a lot, so an unscrupulous tech could easily swap a bad one into your car.
OTOH, maybe the controller is your entire problem. Diagnose it!


Could the heater panel assembly have a bad ground?

Still doubt it.

I'm very frustrated. What else could I try? I hope someone could give me some advice.

Get a wiring diagram and study.
Get a DVOM and test. (Or jumper wires as necessary.)
This is usually all I need to do most electrical diagnosis.

HTH

jagscivic

Thank you for the response. Sorry for the confusing write up. Just had a lot to say. I attached the diagram I used. It has Relay PIN 1 going to the thermal protector to compressor clutch to ground. After what you said, maybe I"m using the wrong diagram (2003 Civic Hatchback verse my Civic LX 4 door).

Based on my attachment you are saying the red wire on the pressure switch is going to the thermal switch on the clutch. So maybe I do have a bad thermal switch?

Is the thermal switch accessible easily?

Do you have the correct wiring diagram? could you emial it to me at jagjeets @yahoo.com?

2. I'll double check the A4 to see if it clicks the clutch on. (I think it only did when I grounded the RED Pressure switch to the BLU/WHT) but I'll double check.

3. Should I order a new Push switch assembly (Recirculation/AC/defogger) panel to correct the LEDs not lighting up?

ezone

I attached the diagram I used.

That looks like a partial diagram, and doesn't quite match the car you have, I assume (I'm using USA diagrams)






It has Relay PIN 1 going to the thermal protector to compressor clutch to ground. After what you said, maybe I"m using the wrong diagram (2003 Civic Hatchback verse my Civic LX 4 door).

I have to assume your diagram is not correct, I am using factory info and it does not match yours. The thermal protector is not wired into the clutch circuit as yours shows.

It IS wired that way on an 01 car though.EDIT: I missed that in the 01 diagram.

Based on my attachment you are saying the red wire on the pressure switch is going to the thermal switch on the clutch. So maybe I do have a bad thermal switch?

Easy enough to figure out.

Is the thermal switch accessible easily?

I dunno, what is easy for you?
Its wires are in the clutch connector near the compressor.

Do you have the correct wiring diagram? could you emial it to me at jagjeets @yahoo.com?

No, I cannot hotlink or copy it. It is factory info. Sorry.


The thermal switch has 2 red wires. One connects to the red wire of the pressure switch. The other connects to the blu/wht wire going to the MICU.




2. I'll double check the A4 to see if it clicks the clutch on. (I think it only did when I grounded the RED Pressure switch to the BLU/WHT) but I'll double check.

If you ground the wire at A4 in the HVAC controller and the compressor kicks on, then your problem is in the dash. Not the engine compartment.


3. Should I order a new Push switch assembly (Recirculation/AC/defogger) panel to correct the LEDs not lighting up?

No.

Test, don't guess.

My diagram shows enough of the inside of the switch set for me to do testing with a DVOM. If I can make the LEDs light with jumper wires, then the switch set is probably good.


HTH

jagscivic

Hey Ezone,

I finally had time to look at the Ac issue. As I mentioned above the blue white wire from thermal switch and the red coming from the Pressure switch had no continuity. I finally had time to put in a new thermal switch and now those two wires have continuity. I"m happy that is fixed. But bad news is that the AC clutch still does not click on using the dashboard switches.

I looked further down the line. It's either bad Heater controller or push switch. I check the push switch using the self test and it worked. The LED still do not come on bright (very dim) but using a multimeter it functions properly.

As you mentioned above, Now that I jump A4 (blue wire) on connector A of heater controller with a jumper wire to A13 (black) ground and the AC clutch came on.

A few questions:
1. WOuld this mean the heater controller has a bad ground internally for the AC system?
2. Looking at the heater controller internal circuit diagram. The blue wire comes in, it looks like there is some internal logic (vertical wavey line, looks like a ~ but vertical). if that logic is correct then the heater controller has a switch to ground. Could the internal logic be checking something, such as evaporator temperature sensor (would that throw a OBD code) or anything else that may not be correct hence not closing the switch to ground?

thanks buddy.

ezone

Your pic is sideways, I can't read it! LOL

Blue wire A4 (?) at the heater control panel: Ground it. If the AC works, then you have a problem within the area of the panel or its associated sensors (evap temp)...
Everything between the panel and the actual AC system is ok enough to run, the multiplex, the PCM, system pressure are ok.

The panel is likely bad. Figure out how to yank yours out quickly, then beg a friend with one that works to use theirs as a test.

None of this will set codes in the PCM.
There may be codes within the heater control panel, you already checked this?



What is
(vertical wavey line, looks like a ~ but vertical).
I don't see that in the diagram.

jagscivic

Hi Ezone,

I got good news, AC problem is all fixed!! Thanks for all your help, you rock!.

To sum up from my last post. The thermal switch was bad and I swapped it for a new one. So that took care of one issue. I then traced the second issue down to a bad heater control ****. When my fiance had the car 6 months ago she took it in and Honda couldn't find an issue and my fiance was like fix it, so Honda changed the heater control "per customer request" (it was a faulty thermal switch, why Honda didn't conclude that, i'm puzzled). So technically the heater control was still under warranty. I took the car to Woodbridge Honda and told them the Heater control was bad and needed replacement. The service guy was like no, you need to pay $75 diagnostic fee and if its the heater control then we'll return the fee, if it's anything else you have to pay it.
Well they called me an hour later and was like it's the push switch assembly and not the heater control. I asked them to check it again, and they were 100% sure it was the push switch. They wanted $165 more. I was like I'll do it myself. I went to the junkyard and tried two push switch assemblies and it didn't fix the problem. (luckily he didn't charge me)
I drove back to Woodbridge Honda told them they were wrong. The Honda service manager looked into it and was like you were right it was the Heater Control. But he was like someone back probed and put power to the ground side and we can't warranty it. But I'm going to give you back the $75 we charged you for diagnostic. I was going to argue the warranty issue, but I had a feeling my buddy's mechanic fried it possibly. I went to the junkyard and got a heater control for $50. Problem solved.


I'm still ticked at honda

ezone

Yay.

Too bad some places expect you to pay for someone to guess at your problems, then expect you to pay again when their guess was wrong...
If they could play "swaptronics" to come up with the correct answer, that would be better, but that isn't always possible.
Few shops anywhere employ a full team of top-shelf talent. Most rely on lower paid mechanics to do the majority of the work, but that is a huge part of typical work.
Seems like electrical and electronics are like some sort of black art or witchcraft to some mechanics. Electricity is usually the "Final Frontier" of auto repair.

/rant

Nitrous1024

I found this thread very enlightening. I just need the necessary tools to remove and inspect my compressor for functionality.

ezone

How are you going to do that if it isn't mounted to the engine, has no belt drive, and isn't connected to the rest of the system so pressures can be read?

I sure can't evaluate one while holding it in my hands.

Nitrous1024

I would want to see if any of the components are worn out inside the compressor itself.
The compressor is just an "accessory" driven by the belt.

ezone

I wouldn't, because:
A) it doesn't pay for me.
B) I don't need to be responsible for it because I took it apart.

I evaluate either good or bad on a running unit, and decide what to do next. Good (to me) means not unusually noisy, and does pump properly.
If good, reuse it. Simple.
If bad, then replace it. Simple.



Hope you can find a rebuild/reseal kit.
Don't even think about trying to reuse any of the original seals after you disturb them.


HTH