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Discussion Starter · #1 ·
Why wouldn't my AC compressor on my 2006 Chevy Cobalt be coming on?

My AC work fine until a couple of weeks ago. The blend door actuator has been broken since I purchased the car and it knocks under the dash every time the car starts, but the AC had been working despite that. Now the snowflake light comes on on the control switch and blows out hot air. I checked and the compressor is not engaging. I replaced the clutch relay under the hood and the AC fuse next to it, as well as the low pressure switch located on top of the compressor. I jumped the relay with a paperclip, and the compressor came on and was blowing cold air. I was able to add freon and oil. Once I removed the jumper and put the relay back in, the compressor will not come on again. The clutch can be moved manually. I am not sure what else would make the compressor not engage. Any suggestions would be greatly appreciated??
 

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I presume you added enough refrigerant to show as properly filled on the gauge on the bottle? The compressor won't engage if the level is too low.
 

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If you checked with a proper set of gauges and had correct readings on suction and discharge sides, it may be electrical.

The relay that turns it is controlled by the ac head unit in the dash, but it also is run through the body control module. I have had to replace quite a few of the head units before. Like you say, the light for the compressor may be lit, but it may also be defective and not actually working right.

Do try swapping the relay with another like relay. Also pop a new fuse in if it had some for the clutch.

If you definitely have the proper refrigerant charge, I would start by using a test light to see if things are actually getting power. Just hope it’s not a control module, although they are known to go bad on these cars.
 

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Discussion Starter · #6 ·
If you checked with a proper set of gauges and had correct readings on suction and discharge sides, it may be electrical.

The relay that turns it is controlled by the ac head unit in the dash, but it also is run through the body control module. I have had to replace quite a few of the head units before. Like you say, the light for the compressor may be lit, but it may also be defective and not actually working right.

Do try swapping the relay with another like relay. Also pop a new fuse in if it had some for the clutch.

If you definitely have the proper refrigerant charge, I would start by using a test light to see if things are actually getting power. Just hope it’s not a control module, although they are known to go bad on these cars.
Thank you. I did actually take it to a shop and have it checked with gauges. I did try swapping the relays and the only way that I could get the compressor to kick on was with a jump on the relay and even then when the compressor kicked on it really bogged down the motor.
I am thinking that it is probably the ecm because the car has been having poor performance, like rough idling, hard shifting, flashing check engine light, loss of power going up hills, and horrible gas mileage.
Could it possibly be like loose or corroded wires, missing ground, or fuse for the ecm in the trunk? Would a bad or failing ecm cause the AC compressor to not engage?
 

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You may wish to give a wee bit more info on the history, type, year, mileage...
Loading the engine down when the compressor kicks in could indicate a compressor about to grenade.
 

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Discussion Starter · #8 ·
You may wish to give a wee bit more info on the history, type, year, mileage...
Loading the engine down when the compressor kicks in could indicate a compressor about to grenade.
Car is a 2006 LS 2.2L Coupe 221,131 miles. I've only had the car about 2 years. Car has been throwing codes for catalytic converter since I purchased it. And the blend door actuator is stuck so it knocks about 10 times in my glove box every time I start my car but the AC had been working great until about 3 weeks ago. Car has been idling rough and having loss of power starting out but drives great on the highway. It starts every time and has not died in me yet. I am just partial to air conditioning. I was driving it with AC on and I pushed the AC recirculation button and it just stopped working. There were no noises or warning signs as to why... I replaced air filters, serpentine belt, changed the oil, bought a new relay, fuse, low pressure switch, recharged and checked with gauges at a shop and still having problems getting power to the AC fuse that is right next to the relay. I have had it in the shop 2 times and they have not been able to determine why the compressor is not engaging. It worked just fine while I had it jumped and had my car like a refrigerator, but as soon as I pulled the jump off the relay the compressor shut off. If the compressor was bad or going bad would it work that good on the jump? I feel like it has to be something electrical. My gauges in my car have also started doing like a ticking after the car has been turned off. And when I was jumping the relay I touched one side of the pin and I heard something clicking??
 

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The blend Door actuator is a $25 part and a +$200 pita to replace. If the AC system is good at the under hood fuse block then it’s not getting the signal from the BCM. This could be just the switch in the control head or much deeper. Coby7 posted the schematics for the AC system here some time back. Finding that would be my first step.
As to your engine miss / low power....200,000 on an 06 is only 100,000 out of usefully life/emission warranty. You can bet your cat and both. And has your car ever had its plugs replaced?

As th the instruments clicking after you turn off the engine...this makes me think of a poor electrical connections at the BCM.
 
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