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Discussion Starter #1
Greetings all. Yes, I know this is a common problem. And no, the common fixes don't work.

2008 MDX, about 150,000 miles. New A/C compressor at about 130,000.

Air conditioner randomly works/doesn't work.

Compressor is new, so not worried about coil.
Freon is correct.
When it works, the A/C is ice cold.
When it doesn't work, the blowers work fine, but the compressor does not kick in, so it's just ambient air temp.
Sometimes turning climate control on/off, or stopping and restarting the engine seem to get it working. But maybe it has nothing to do with control inputs.

Have replaced under hood relay repeatedly. Sometimes it seems to work like a charm, other times, no.

On a side note, we have also had a problem with the rear air unit suddenly blowing hot air, even when it should be blowing cold like the front.

Any other brilliant ideas? Is there a computer than runs the climate system, that might be acting up? Would getting a new climate control for the dash work?

Getting frustrated here.....
 

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Just guessing here … is it possible that some of the blend motors are not working properly? Do you hear any clicking coming from under the dash?
 

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Check whether compressor is getting 12V to single wire to compressor when AC commanded On.

If 12V present on single wire to compressor, then compressor clutch coil is bad or excess clutch gap (yes, I know it's new).

If 12V missing at compressor, then something in AC control system is preventing AC compressor relay from being energized (numerous possibilities; hi/lo pressure switch, vehicle temp sensor, PCM, thermostat, etc).

good luck
 

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Do you have the Acura original service manual? There is a diagnostics you can run from the AC controls.

By the way, there is a new part number for the hood relay with better contacts than the original factory relay.
 

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Discussion Starter #7
No service manual. Will try to Google up the diagnostic. I recall seeing it at one time, don't recall where.
 

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Did you run the diagnostics? Any codes reported?
 

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Discussion Starter #11
No codes. Display just stayed blank. I guess that means no codes. I wish it would have blinked to let me know it was running the diagnostic.

I checked the magnetic clutch clearance. It was too wide. I took out one 0.5mm shim, which makes it slightly closer than spec. I think I'm going to try it that way, anyway.
 

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Did you see anything in the display? Did the fans run as part of the test? Anything?
 

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No codes. Display just stayed blank. I guess that means no codes. I wish it would have blinked to let me know it was running the diagnostic.

I checked the magnetic clutch clearance. It was too wide. I took out one 0.5mm shim, which makes it slightly closer than spec. I think I'm going to try it that way, anyway.
Spec for clutch gap from my 03-06 manual is 0.35-0.6mm.

good luck
 

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Discussion Starter #14
Saw and heard nothing. Display stayed blank, nothing kicked on. Waited 30-40 seconds. How quickly does it happen?
 

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Discussion Starter #15
Spec for clutch gap from my 03-06 manual is 0.35-0.6mm.

good luck
Thanks. Gap befre removing shim was >0.65mm, which was the biggest gauge I had. After, it was about 0.26mm. I know that's tighter than spec, but I couldn't find any shims at the FLAPS. Mine had 1mm of shim, two 0.5mm shims, so I took one out.

Have also been having electrical gremlins of the FM and AM radio stations don't hold in memory. The XM stations are retained, however.

So I cleaned and retightened the battery ground (-) cable, including scuffing down to bare paint where the cable bolts to the body. I figured a cleaner ground might help. Or at least, couldn't hurt.

Drove about 2 hours/150 miles today. A/C worked just fine the whole trip......
 

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Good to hear. Hope fix is permanent.

good luck
 

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Drifter,

Keep up updated with your problem. Definitively a low quality ground connection will cause all kind of problems in the electronics. Good to hear you are not having A/C issues at this time.

In regards the diagnostics, I will run it on my MDX this evening and will report back what I see on the display.
 

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Discussion Starter #18
I was getting the MDX ready for a big road trip, but circumstances have changed, so the MDX stays home. That being said, I've been driving it only a little while getting ready for the trip. However, since the adjustments mentioned above, the radio memory has been holding the stations. The A/C has not cut out. Will report back in a few weeks when we get some more miles on it.
 

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Discussion Starter #19
So we take another road trip, compressor quits working. We get home, I leave it running while we unload, then take it directly to my local mechanic. He puts on a lift with the A/C and engine "on" and the compressor not turning. He touches the wires to the compressor clutch...

IT WORKS

Simply the plug on the A/C compressor was bad, $10 plug, $20 labor, has worked for months now.

Yes, I am equal parts relieved, frustrated, and embarrassed.
 
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