2005 Air Conditioning Issue

[Tinman76]

2005 Grand Prix. My a/c was working intermittently. Usually you turn it on and off a few times and it would work. Sometimes 5-10 minutes down the road it would blow nice and cool. Now I can't get it on at all. Fan blows and replaced the blend door motor. Checked fuses and swapped relay. No codes. Need some ideas here. Where to look next? Thanks.

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[bandook]

Could just need topped off. If the pressures aren't right it won't engage.

[Tinman76]

So it worked while driving a few minutes ago. I just hooked up on a charge kit and its reading really high. 100psi. Should I let some out or is that the sign of a bigger issue.

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[mars5l]

If the low side is reading 100 psi is a sign its not coming on, I bet the high side will also say 100 psi because the system is equalized. Does it only work when driving then stop working when you stop?

[Tinman76]

If the low side is reading 100 psi is a sign its not coming on, I bet the high side will also say 100 psi because the system is equalized. Does it only work when driving then stop working when you stop?

My mistake. Didn't have the car running. Have about 32psi running. Starting to think it may be something with the auto temp control. Is there a sensor that could be going bad?

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[Tinman76]

Also my outside temp is messed up. Sometimes it reads right, many times it says its 20 degrees out when its 80.

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[Scottydoggs]

if thats messed up the ac wont work right. the sensor is clipped to the rad support or in front of the rad between the bumper and radiator.

iirc its a dealer item @ 30 bucks.

[Tinman76]

if thats messed up the ac wont work right. the sensor is clipped to the rad support or in front of the rad between the bumper and radiator.

iirc its a dealer item @ 30 bucks.

Great. Will pick one up. I'll swap that and go from there.


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[Scottydoggs]

looks like this, check the parts store they may have it. this pic i got from auto parts warehouse site. http://www.autopartswarehouse.com/sh...rand_prix.html

Pontiac Grand Prix Ambient Temperature Sensor,

[Tinman76]

Awesome. That pic will help. Will get one tomorrow. Thanks.

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[J57ltr]

My mistake. Didn't have the car running. Have about 32psi running. Starting to think it may be something with the auto temp control. Is there a sensor that could be going bad?

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32psi is too low, you also need to check the high side pressure as well. At around 75-80* you should have 45psi on the low side and 240 on the high side. Run Max, air fan full blast when checking it.

When you rev it up your low side will drop below 32 psi and I don't know when the low pressure drops out but you're probably reaching it.

Jeff

[Tinman76]

So I bought a set of gauges after I overcharged my ac. Compressor now cycles on & off for 5 seconds constantly. Doesn't blow cold. So now I have about 45psi low side & 350-450psi on high side when it's running.

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[mars5l]

Your highside is wayyyyyy too high. Almost sounds like you have a blockage.

[Tinman76]

I definitely overcharged the system with the crappy kit they sell. I reduced the high side to around 250psi. AC is working again. Actually better then it's been in a long time. Checked the vents and its coming out at 50 degrees. Not sure if it will last but shall see I guess.

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