A/C Issue and Noise

Discuss any problems, warranty, repair, or replacement issues you are having with your Vibe & Matrix
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frostyvibegt
Posts: 16
Joined: Thu Jan 11, 2018 6:25 pm

A/C Issue and Noise

Post by frostyvibegt »

Hi, I have a 2004 Pontiac vibe base with about 770000 miles on it , yes it has that many the odometer has reset twice now. i was wondering if it ws normal to hear two pops when the car is started and the ac engages. shortly after there will be a horrible grinding noise that will last until you turn the car off. it only does it when its below 70 should i be worried.
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joatmon
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Joined: Fri Mar 21, 2003 5:19 am
Location: SMC MD

Re: A/C Issue and Noise

Post by joatmon »

does the 2 pops happen when starting only if the climate controls would run the AC, or all the time? The AC will run when either the AC button is pushed or if the airflow is set to full or half defrost. When the AC engages, the magnetic AC compressor clutch can make a loud clack sound, usually one when it engages, quieter when it lets go

A grinding noise might be caused by one of the blet driven things on the engine. A relatively easy way to test that is when the engine is cold, remove the serpentine belt, start the car and see if the grinding noise is still there. Don't run the car for very long without the belt, but a quick test on a cold engine should be ok. On VIbes, a common belt driven noise failure item is the belt tensioner. If you think its the belt tensioner and go to replace it, be sure to first read viewtopic.php?f=28&p=509713
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frostyvibegt
Posts: 16
Joined: Thu Jan 11, 2018 6:25 pm

Re: A/C Issue and Noise

Post by frostyvibegt »

the grinding noise is associated with engine speed but only happens when the ac is engaged the two pops happens is the ac button is on when the car is turned off and still on the next time you start the car.. also do you ever notice any ac whispering ( i don't know how to explain it) it sounds like someone whispering loudly
frostyvibegt
Posts: 16
Joined: Thu Jan 11, 2018 6:25 pm

Re: A/C Issue and Noise

Post by frostyvibegt »

joatmon wrote:does the 2 pops happen when starting only if the climate controls would run the AC, or all the time? The AC will run when either the AC button is pushed or if the airflow is set to full or half defrost. When the AC engages, the magnetic AC compressor clutch can make a loud clack sound, usually one when it engages, quieter when it lets go

A grinding noise might be caused by one of the blet driven things on the engine. A relatively easy way to test that is when the engine is cold, remove the serpentine belt, start the car and see if the grinding noise is still there. Don't run the car for very long without the belt, but a quick test on a cold engine should be ok. On VIbes, a common belt driven noise failure item is the belt tensioner. If you think its the belt tensioner and go to replace it, be sure to first read viewtopic.php?f=28&p=509713
the grinding noise is associated with engine speed but only happens when the ac is engaged the two pops happens is the ac button is on when the car is turned off and still on the next time you start the car.. also do you ever notice any ac whispering ( i don't know how to explain it) it sounds like someone whispering loudly
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joatmon
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Joined: Fri Mar 21, 2003 5:19 am
Location: SMC MD

Re: A/C Issue and Noise

Post by joatmon »

I haven't noticed any whispering.

It's hard to say from here what might cause a grinding noise when the AC is running. Easiest guess is that the compressor is failing, but when the AC engages, it puts an extra load on the belt, which could theoretically affect something else on the belt. If not the compressor, then I'd suspect the tensioner next, before the alternator, power steering and water pump. Might try with the car idling in park, see if you can locate the source of the sound while someone else turns the AC on and off. Maybe feel the compressor when its grinding to see if you can feel a grinding related vibration.
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