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Hello,

All of a sudden the AC stopped working. AC light comes on when I push the button, cab fan comes on. Compressor does not engage and the radiator cooling fans don't come on.

Is there a checklist or some way to diagnose the problem?

I believe there is good freon pressure.

regards,

redbug2

 
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the first thing to check would be fuses

 
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This would be my first thing to inspect.
I need proof, not beliefs.



There's always a way.

 
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Ezone, yes, I agree, need more than a belief.

I did put a can of freon that had a guage on the line and it was in the red, which indicated to me that It was high pressure. I have a set of converted guages I'll throw on the low and high side to get readings.

I checked all of the fuses under the hood that seemed related to the AC, they all looked good.

Thanks for everyones help.

 
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try and get the codes from the HVAC system. just follow the instructions in the image. Hope these help.

 
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^If no codes are revealed and the system does have sufficient pressure to operate, but does not, then there are other checks that can to be done.

I see you've been posting service manual diagrams. Thanks! (I can't do that.)

 
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Ran the diagnostic test and no blinking AC light, so, no errors found.

Put the guages on the high and low line. Note that the compressor is not turning...

Is there a test I can run to test the compressor clutch?

 
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Heres what I've found so far for the Compressor Clutch diagnostics. hope this helps!

 
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OK system has sufficient pressure to operate the compressor.

You turned the system on, and find no compressor operation.



Check 1) Do the radiator fans come on when you turn on the AC?

a) If the fans DO come on, then I'd go directly to clutch relay for my next check, with a simple test light first.



b) If the fans do NOT come on, then I'm looking at my scanner to see if there is an AC request at the PCM.
OR
I could manually check for this request signal anywhere between the HVAC controller and the PCM. This circuit includes the pressure switch, the thermal protector on the compressor, and the multiplex control unit.

 
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And, how'd you get the compressor to run? I thought you said it still wasn't running in the post that was showing the gauge set at 100 PSI.

 
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ezone,

I think red_chaos1 is hijacking my problem or has a similar problem?

My compressor does not run. My cabin fan does come on but my outside radiator fans do not come on.

I'm in Southeastern PA, yesterday it was 88, fairly hot for this time of year.

I'll try some more of the tests this evening after work.

Thanks again for everyones help.

 
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Two different persons having AC problems and discussing them in the same thread at the same time. This is what probably made it confusing.

 
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You have 100 PSI in your system.
No compressor and no radiator fans, tells me the PCM is not turning the system on. You can't see the request from the PCM, so checking the circuit is the next best thing (IMO)
You need to check the "request" line to see if the ground (request signal) is getting all the way from the HVAC controller to the MICU and PCM.
Get a wire diagram if you need to

 
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Separated posts related to Red_Chaos1 and moved to his new thread.

Hope I got the right posts moved LOL

 
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Engine running, controls set for AC to be on:

Unplug the pressure switch 2 wire connector (on top of the receiver-drier).

Test: Is there a ground on the blue wire?

Manually connect (jumper wire) a ground to the red wire. Does the compressor and radiator fans all kick on?

 
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OK, back on the computer for more instruction... Followed the diagnostics and found all fuses in good shape. Pulled off relay and crossed 1 and 2, compressor came on, cold air, no radiator fans... We are elminating the variables! Thankfully the compressor and clutch seem to be good.

Came in to find out where the ECM/PCM connector is for next step and I see Ezone's latest response. I'll try the pressure switch connector jumper next then on to the ecm/pcm.

OK, update, Pressure switch connector had ground with blue wire. Jumper from red to blue would not start fan or compressor. Took out relays for fans and bypassed with jumpers, each fan started. So, compressor is good, fans are good.

I still don't know what/where the ECM/PCM is, I'll keep looking.

Thanks again.

 
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Next spot in the circuit is the thermal limiter on the compressor.



Reconnect the pressure switch.
Unplug the 3 wire connector at the compressor. Start the engine, turn on the AC system

Hold the engine harness connector in your hand.
The red wire that was at the pressure switch is now at the connector in your hand. It should test as a ground. Does it?

Now supply a ground to the blue/white wire using a jumper wire.
Do the fans kick on?

If they kick on then ohm test the thermal switch wires on the compressor plug. (the two outer wires in the 3 wire plug)

If they don't kick on, then you'd head for the Multiplex unit or PCM. I'd probably go for the multiplex unit.....Are there any other odd electrical issues in the car that might be related to the MICU?


Found a diagram, finally!






It's behind the glovebox, up above some of the HVAC stuff.

 
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Did not have the instructions with me... Took me about 45 minutes to get the harness connector out, big hands and rusted mount. Finally got it.

Tested the harness connector. Kept the car on but did not start it. No ground on Center Blue with gray ring. No ground on Red.

Grounded blue with white and both fans came on.

I'll start the car tomorrow and check for ground on the connector.

Did not get to the compressor wires yet...

Where is the multiplex unit?

There is an aftermarket remote starting system in the car with an alarm system. It hasn't been acting up and I'm hoping its not related to the AC Problem.

 
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STOP.


Go back to this line:
Refer to the diagram picture above.
You have this narrowed down to the thermal protector, or the red wire between the thermal protector and the pressure switch.

Test each appropriately.



EDIT: Multiplex unit is built into the dash fusebox. You don't need to care about that now.

 
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Agreed,

I will follow the plan.

Just did a quick check today, ran out of time, if I hadn't spent 45 minutes getting that connector loose I would have come in and printed off the instructions...

Thanks again for your help.

 
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You said:

"If they kick on then ohm test the thermal switch wires on the compressor plug. (the two outer wires in the 3 wire plug)"

Tested outer wires, no continuity between the outer wires. Thermal switch must be toast.

I guess it has to come out. Bummer that I had just replaced the timing belt and now I have to go back in there! From what little I have read I should be able to do this without removing the compressor.

Local honda dealer said $75, I'll see if a parts store has it but somehow I doubt it.

If I'm on the right track I'll start the job tomorrow morning.

Thanks.

 
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Price at Majestic:

38908-PLM-A12

PROTECTOR SET, THERMAL
65.20 45.64
Looks like your dealer is $10 over MSRP. Mail order is cheaper yet, $46 plus shipping.


2001 and 2002 use different part numbers than 2003-05.


Looks like you just get it to where you can reach the goofy thing on top of the compressor, remove a bolt/ground wire/bracket, and replace it.... Only note is to glue it in with a tiny dab of silicone sealer (RTV).

No messing with freon or anything, probably just get the alternator out of the way for access.

Replace the thermal protector, then see if the compressor runs and it cools OK again.

 
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Ok, Finally got around to installing the part.

Took out power steering pump and alternator.

Spent most of the time removing the old thermal protector. Created a long tool out of a rod of steel that I could lightly tap down with a hammer. Ground down the end to a small point and poked and bent the old piece out. Dremel was not very helpful until the end where I could use the wire brush.

PC-7'd in the piece. Should do it.

Started up car, no AC... Looked at the connections and I must have left the pressure switch off during testing. Popped it back on and bingo, AC!

Thanks for all of the help ezone.

Regards,

 
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AW POOP!!!

*looks around to see if anyone heard the yelling a minute ago*
*gloat, dust off knuckles*


YW, glad it worked out