AC Help?!?!?
Thread Starter
Teching In
Joined: Nov 2014
Posts: 3
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AC Help?!?!? So, I was told I have a bad compressor, ok... so I replaced the entire AC system, charged it, and got everything put together. But here's the kicker. The compressor won't kick on. Pressures are good. Charge is good. I tried swapping the relay, didn't fix it. I tried jumping the relay. Still nothing. I don't think the compressor is getting power. What can I do to make sure it does? I've only had the car for a short time, and the AC has never worked.
Ideas?
Ideas?
So, I was told I have a bad compressor, ok... so I replaced the entire AC system, charged it, and got everything put together. But here's the kicker. The compressor won't kick on. Pressures are good. Charge is good. I tried swapping the relay, didn't fix it. I tried jumping the relay. Still nothing. I don't think the compressor is getting power. What can I do to make sure it does? I've only had the car for a short time, and the AC has never worked.
Ideas?
Ideas?
TECH Fanatic
Joined: Nov 2011
Posts: 1,367
Likes: 144
From: Woodstock, GA
So, I was told I have a bad compressor, ok... so I replaced the entire AC system, charged it, and got everything put together. But here's the kicker. The compressor won't kick on. Pressures are good. Charge is good. I tried swapping the relay, didn't fix it. I tried jumping the relay. Still nothing. I don't think the compressor is getting power. What can I do to make sure it does? I've only had the car for a short time, and the AC has never worked.
Ideas?
Ideas?
If the compressor is found to be bad, it's best to replace the compressor, filter/drier and all seals before putting in a vacuum. Curious as to what was wrong with the compressor also.
TECH Fanatic
Joined: Nov 2011
Posts: 1,367
Likes: 144
From: Woodstock, GA
No I was just confused as to how the shop that said the compressor deemed it bad when the clutch wasn't even kicking in. And yes ... I agree with putting a new receiver/dryer and orifice tube in there when swapping the compressor.
Teching In
Joined: Apr 2017
Posts: 2
Likes: 0
From: Slidell
check voltage at the ac compressor relay terminals. You should have 12v on one side of the relay coil and at the input terminal. If you have voltage there check to see if the relay coil receives a ground on the other side of the coil when the ac is turned on. If no ground is received, the relay coil won't energize. The cause of this could be a bad ac pressure sensor.
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per my 2002 service manual, should apply to 1998-02, the ac compressor clutch wont get power unless a few conditions are met such as (going from memory) engine rpm below 4000, engine coolant temp below ~230f and so on. but the two big ones are the ac low and high pressure sensors reading above ~20psi and below 300 of 400 psi. ideally u want a scan tool to verify the pcm sees the hvac head unit in dash is first working and sending signal to pcm, then pcm (if various parameters are met) grounds ac compressor relay which then sends power to ac clutch. it could be as simple as a bad connector at the ac compressor. it could also be a bad hvac unit in the dash... rare but it happens.
also, and this is where a good scan tool is really useful, your pressure gauges might show the system is charged but if the PCM does not see the signal from the pressure sensors for whatever reason then the pcm will never command the compressor clutch to activate. unfortunately you can only go so far with troubleshooting until you need the scan tool to see that live data, unless you chance it by replacing parts and hoping it fixes it (head unit, wiring harness, pcm, etc.). ... but i just saw "you jumped relay" so provided you jumped the correct wires and didn't kick the compressor clutch i would lean towards a bad connector or broken wire.
also, and this is where a good scan tool is really useful, your pressure gauges might show the system is charged but if the PCM does not see the signal from the pressure sensors for whatever reason then the pcm will never command the compressor clutch to activate. unfortunately you can only go so far with troubleshooting until you need the scan tool to see that live data, unless you chance it by replacing parts and hoping it fixes it (head unit, wiring harness, pcm, etc.). ... but i just saw "you jumped relay" so provided you jumped the correct wires and didn't kick the compressor clutch i would lean towards a bad connector or broken wire.
Last edited by 1 FMF; Jun 1, 2017 at 08:40 AM.
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