Mechanics

- AC NOT WORKING. BAD ECM SWITCH?

2002 Nissan Sentra

My sister has a 2002 Nissan Sentra GXE and the AC hasn’t been working for almost 3 years now. She took it to a mechanic who told her it would cost over 1k to fix because the problem was that “the ECM switch was not grounding to the AC relay”. Admittedly I know very little about cars, especially the electronics of them, but I don’t trust these guys. This same garage told me that I needed to replace my power steering harness thingy (that’s how much I know about cars) because it was leaking. They verbally quoted me $700.00 for the work, which I declined, but when I reviewed the write-up they did on the problem later, the fine print at the end actually said the cost would be $1,100.00. Not only that, but I took my car somewhere else and they couldn’t find anything wrong with my power steering system. Long story short, I’m not convinced that the ECM switch is the real culprit of the Nissan’s AC problems.

Is there a way to test this ourselves and avoid another garage fee?

Not sure if this is related, but the speakers went out shortly after the AC pooped.

Any ideas/tips would be very much appreciated.
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KMDLEE
May 11, 2011.




I'm not convinced either. That ground wire is the control wire for the PCM to control the A/C clutch. It monitors numerous things before it makes the decision to turn on the relay. It's not the computer's fault if it's not turning it on. It's just not satisfied with something else in the circuit and is refusing to turn the A/C on. That's what needs to be found.

Wrenchtech
May 11, 2011.
We followed up with the garage to see if we could get the diagnostic codes from when they performed the test, but they didn t have them . They reviewed the notes on the car and now are saying that the PCM needs to be replaced, and the thermo switch needs to be replaced, then the PCM needs to be flashed . Based on what you said and on some research I ve done regarding the PCM, wouldn t it make more sense to find the root cause of the problem in the circuit by testing the flow of current across the system first? Or at the very least just replace the thermo switch and see if that fixes the issue before replacing the PCM?
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Tiny
KMDLEE
May 12, 2011.
I find it hard to believe that PCM is bad. Unless this is the dealer that is working on it, I think they are misdiagnosing it.

Wrenchtech
May 12, 2011.

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