AC blows cold sometimes and Hot sometimes

Tiny
KEVIN LEAMER
  • MEMBER
  • 2004 CHEVROLET CAVALIER
  • 4 CYL
  • AUTOMATIC
  • 126,707 MILES
Tried to charge Freon. Gauge said it was either overcharged or there was a mechanical failure. Compressor keeps cycling on then off.

Do not know much about cars so any information would help. Can replace compressor but is there anything before the compressor that could possibly make it cycle on and off?

Thanks,
Kevin
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Thursday, September 22nd, 2016 AT 2:16 PM

32 Replies

Tiny
ED-WEEZY21
  • EXPERT
Hey there. When you say that the compressor cycles on and then off, does it cycle back on? Most AC compressors have a clutch and they are designed to cycle on, off, on, off, etc. Also, you say you're trying to charge the freon but do you know how much freon is actually in the system already? Best way to recharge the ac system is to perform an evacuation of all the freon using an AC machine and then performing a vacuum on the system. Monitor the gauges to check if you start to lose your vacuum which would indicate you have a leak somewhere. If the vacuum remains the same, then you recharge the system with the appropriate amount thats located on the AC placard somewhere in your engine bay.
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Thursday, September 22nd, 2016 AT 5:04 PM
Tiny
KEVIN LEAMER
  • MEMBER
Yes the compressor cycles on/off then on/off repeatedly. I was not sure if that was normal or not. Not sure how much Freon is in system. Gauge on Freon kit said that it was either over charged or mechanical failure.
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Thursday, September 22nd, 2016 AT 5:56 PM
Tiny
SATURNTECH9
  • EXPERT
Just to add to this one that is not a cycling compressor most GM cars are not. The gauge cannot tell you how much charge is in the system. That is why it is best to charge a empty system so you know you have the correct amount of charge. Or what the professionals use a AC machine so they can evacuate and weigh what comes out. So they no how much charge was in the system to know if it was fully charged over charged under charged etc. Also reasons for compressor cycling too high of pressure built so compressor is shut off as well as too little of pressure can shut off as well. Also not enough air being pulled through the radiator and AC condenser do to sand debris fan not working etc.
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Thursday, September 22nd, 2016 AT 7:22 PM
Tiny
ED-WEEZY21
  • EXPERT
Thanks saturntech9 for clarifying if his compressor was a cycling compressor or not. All cars I have worked on so far have a clutch. Everything else is spot on as well. Thanks for reassuring.
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Friday, September 23rd, 2016 AT 4:58 AM
Tiny
SATURNTECH9
  • EXPERT
They all have a clutch or a bypass valve they use instead of a clutch to bypass the pressure to do the same thing a clutch does. You are welcome anytime we are here to work as a team.
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Friday, September 23rd, 2016 AT 7:11 AM
Tiny
KEVIN LEAMER
  • MEMBER
Thanks everybody. Still confused, lol. Have a buddy who is more mechanical than me so we are going work on it this afternoon. I will let you know how it goes.
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Friday, September 23rd, 2016 AT 7:35 AM
Tiny
SATURNTECH9
  • EXPERT
Alright, keep us posted.
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Friday, September 23rd, 2016 AT 12:51 PM
Tiny
KEVIN LEAMER
  • MEMBER
Did not have a chance to work on it today going to work on it tomorrow morning. Seems as though the AC blows cold in drive but hot in idle?
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Friday, September 23rd, 2016 AT 9:59 PM
Tiny
SATURNTECH9
  • EXPERT
So while driving down the road it blows cold, but when you stop moving it blows. Hot?
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Friday, September 23rd, 2016 AT 11:34 PM
Tiny
KEVIN LEAMER
  • MEMBER
Yes, I noticed that today.
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Friday, September 23rd, 2016 AT 11:43 PM
Tiny
SATURNTECH9
  • EXPERT
So is your radiator fan/condenser fan turning on with the AC?
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Friday, September 23rd, 2016 AT 11:47 PM
Tiny
KEVIN LEAMER
  • MEMBER
Something definitely turns on when I turn on AC, but then it sounds like it is cycling on and off. I thought it was the compressor. But you explained it does not do that on my model. It sounds like it comes from middle of engine but I did not see anything moving. Granted I did this on my fifteen minute break by myself so I am sure I missed something. So should I check to see if fan is on first thing tomorrow?
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Friday, September 23rd, 2016 AT 11:54 PM
Tiny
KEVIN LEAMER
  • MEMBER
Thanks for all your help again.
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Friday, September 23rd, 2016 AT 11:55 PM
Tiny
SATURNTECH9
  • EXPERT
Yes see if the radiator fan/condenser fan turns on with the AC? Does your radiator fan turn on when the car warms up?
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Saturday, September 24th, 2016 AT 12:06 AM
Tiny
KEVIN LEAMER
  • MEMBER
I believe so because otherwise it would over heat correct?
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Saturday, September 24th, 2016 AT 12:09 AM
Tiny
SATURNTECH9
  • EXPERT
I have seen strange things with radiator fans not working and people only complaining about the AC only working when driving.
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Saturday, September 24th, 2016 AT 12:14 AM
Tiny
KEVIN LEAMER
  • MEMBER
Point taken. I will look tomorrow and let you know.
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Saturday, September 24th, 2016 AT 12:39 AM
Tiny
SATURNTECH9
  • EXPERT
Keep me posted.
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Saturday, September 24th, 2016 AT 1:09 AM
Tiny
KEVIN LEAMER
  • MEMBER
Okay so started car and let run. Fan never turned on. Started AC. Clutch engaged fan still did not turn on. The on off noise I heard was the clutch engaging and turning off which it started to after five minutes of idle. Temperature went up two lines from normal, but did not seem to get any hotter. Thoughts?
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Saturday, September 24th, 2016 AT 12:29 PM
Tiny
SATURNTECH9
  • EXPERT
Sounds like the radiator fan is not working properly. With the AC on at idle try smacking the fan motor see if the fan starts spinning?
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Saturday, September 24th, 2016 AT 12:31 PM

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