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Amedee
Amedee, Pontiac Technician
Category: Pontiac
Satisfied Customers: 25638
Experience:  ASE certified Technician advanced level specialist. Wisconsin certified emissions state inspector
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99 Grand Am GT - A/C Clutch not engaging

Customer Question

99 Grand Am GT - Put gauges on and unit shows pressure (around 100 psi) HI and LO side with unit not running - seems to have charge - compressor will not engage clutch. Have swapped relay to no avail. Appears to be electrical? How does one check to see what is the broXXXXX XXXXXnk in the process? How do you check the high side switch? What should I check starting at the front of the process and continuing through till I find the problem?
Submitted: 7 years ago.
Category: Pontiac
Expert:  Amedee replied 7 years ago.

Greetings! If your air conditioning in not working, or working but not up to par, there can be a few different things that can cause this. There can be anything from restrictions in the system to your blend air door vents not working properly. First and foremost is look to see if your compressor is coming on. If all of your freon has leaked out or even if the freon level is a bit low, the computer will not turn on the compressor. This is to prevent damage to the compressor and the components. This is very common! If the compressor is cycling on and off, than the system is just slightly low on freon. This will cause the AC to work, but poorly. Look for moisture around the outside of the AC fittings. This will indicate a leak. If no moisture is detected, you might just be able to get away with recharge

 

Customer: replied 7 years ago.
Please read my question. It is specific. I was expecting more than a generalized "things that can wrong wrong with any AC system".. Not trying to be wise here, just looking for an informed decision..

Thanks very much for any help regarding the question you can offer..
Expert:  Amedee replied 7 years ago.

Sure... not a problem.

 

How much freon is in the system?

Customer: replied 7 years ago.
When I put my gauges on it (motor or compressor not running) I show around 95 psi equalized.. I found a 10 amp fuse blown (#37) replaced it but nothing. I swapped the horn relay with the AC relay and nothing..
Trying to decide what the next action should be. I have limited test equipment (have multimeter and gauges)..

I appreciate you trying to help..

Mark
Expert:  Amedee replied 7 years ago.

Well, to be honest with you we need to start by evacuating and recharging the system. THis is what we do with every car that comes in with an AC problem. We need to put a full charge on it and start from there. THis is because the computer will not even turn the AC compressor on when it is low on freon. THis is to prevent damage to the AC components.

 

You can try to jumper the high and low pressure switch to see if the compressor kicks on. IF it does, chances are you are just low on freon.

Customer: replied 7 years ago.
>>You can try to jumper the high and low pressure switch to see if the compressor kicks on..

I understand this I have done it on my other GM cars, but, I cannot find nor do I see a reference anywhere to a low side pressure switch to jumper.. There's only a relay?
Expert:  Amedee replied 7 years ago.

Look on the compressor. There should be a switch there.

Expert:  Amedee replied 7 years ago.
THe relay is located In the left side of the engine compartment fuse box
Expert:  Amedee replied 7 years ago.

Hello!

 

DId you have any luck?

 

DId you find it?

Customer: replied 7 years ago.
Re: >>THe relay is located In the left side of the engine compartment fuse box

Let's stop wasting each other's time. In my FIRST message I stated that I already checked the relay.. Sorry to waste your (and MINE) time. I was expecting something other than really elementary answers to a fairly detailed question.

BTW, the relay is on Driver's Side...

I guess I will keep searching.


Expert:  Amedee replied 7 years ago.

You asked about the relay so I was telling you the locations of the relay.

 

If you stick with me, I will be able to get to the bottom of this problem for you.

 

DId you find the pressure switch?

Customer: replied 7 years ago.
"You asked about the relay so I was telling you the locations of the relay.
If you stick with me, I will be able to get to the bottom of this problem for you."

I never asked, I told you I had already checked it. That's why I got exasperated.


"DId you find the pressure switch"

I found the high side pressure switch (located at front just before condenser) but not the low side switch. There is nothing by the compressor.
Expert:  Amedee replied 7 years ago.

Ok...

 

Sorry about that. I must have read your post wrong.

 

ANyway, does the compressor come on when you jumper the high side pressure switch?

Customer: replied 7 years ago.
The high side switch has three wires - black red and green - it is not like a typical lo side pressure switch..
Expert:  Amedee replied 7 years ago.

Ok... sorry about that. My connection was bad for a bit.

 

Any way, you are aware that the computer will not even turn on the AC compressor if you are low on freon, correct? Every time we get a vehicle in for any AC work, the first thing we do is evacuate and recharge the system. Then you can see if the compressor comes on. I would be willing to bet your compressor would come on if you filled the system with the correct amount of freon.

Customer: replied 7 years ago.
OK so you go back to square one? I'm done wasting time.

Thanks.. You really should re-read this conversation to see why I am so frustrated..