AC clutch not engaging all the time - Chevy Impala SS Forum
 
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post #1 of 7 (permalink) Old 07-23-2016, 09:41 AM Thread Starter
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AC clutch not engaging all the time

Just used one of the autopart stores refridgerant refills and the ac blows cold. But sometimes when i turn on the car and start the ac the clutch isnt engaging at all. What could be the problem? Once it engages it blows cold air fine, it just wont engage all the time.

96 BBB Impala SS
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post #2 of 7 (permalink) Old 07-23-2016, 10:30 AM
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First thing I would check is power to the compressor connector, the next would probably be a bad clutch assembly if you get power to the connector everytime you activate the A/C switch.

1996 DGGM Impala SS
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post #3 of 7 (permalink) Old 07-23-2016, 10:43 AM
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Just a lag? Or rapid cycling, - can't tell from your description. Even where you are I'm sure you've discounted the temp just being set close or higher than outside. Set it on 60/MAX and observe any more consistent operation.

Did this autopart stores refrigerant refill at least have the moveable fill range pressure indicator according to outside temperature?

And if an original clutch, then indeed at 20 years old it may be letting go. Mine exploded 4 weeks ago on the interstate. I noticed just before that it was not blowing quite so frigid. Lucky me - there's still positive pressure in the system though.

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post #4 of 7 (permalink) Old 07-23-2016, 08:51 PM
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It could be the clutch, or one of the pressure sensors. The 92-96 cars have a low pressure (on the accumulator) and high pressure sensor (on the compressor). If either is not making contact, it will not allow the clutch to engage. Check your voltage at each of them when the HVAC is on, and the clutch is not engaging. If they have B+ on the clutch side of each connector (check the connector for the low side at the high side connector, and the high side connector at the clutch), then it is probably your clutch. Your pressures could be off as well. You need to check them.


You may also have an issue with the relay for the HVAC. Check it as well. You can check for B+ on the "car side" of the low pressure switch connector.


If you are sitting at a light, sometimes the compressor will turn off depending on the outside temperature. The compressor will turn back on when you start moving.

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post #5 of 7 (permalink) Old 07-24-2016, 11:54 AM
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Quote:
Originally Posted by TABlaylock31 View Post
Just used one of the autopart stores refridgerant refills and the ac blows cold. But sometimes when i turn on the car and start the ac the clutch isnt engaging at all. What could be the problem? Once it engages it blows cold air fine, it just wont engage all the time.
All the full sized GM vehicles made like these have a low pressure cutout switch . these fail esp when very very old like 20 yrs old. also if you have been operating with low refrigerant for some time that switch gets over worked because it will constantly open when the pressure drops toooo low. this is to protect the compressor. no refrigerant no lubing of it .

I would put a pressure gauge on the low side start vehicle see if the clutch cuts in @10 psi or more pressure . if you have more than 10 psi, and it does not engage , then short out the switch ., if the compressor runs then the switch is bad.
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post #6 of 7 (permalink) Old 08-01-2016, 02:19 AM Thread Starter
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Well i havent gotten around to testing anything because the air has been running perfect the last week or 2. Does this help give any indication of what might be going out? The fact that it runs good without problem for weeks, but then wont work for a trip or 2?

96 BBB Impala SS
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post #7 of 7 (permalink) Old 08-01-2016, 08:39 AM
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Well i haven't gotten around to testing anything because the air has been running perfect the last week or 2. Does this help give any indication of what might be going out? The fact that it runs good without problem for weeks, but then wont work for a trip or 2?
that low pressure switch is just a screw in component. has a valve under it so no tools required , remove the wire connector and unscrew. then screw in replacement ...

not a pressure problem it is most likely electrical like that switch.

also if the ac compressor clutch is worn so that it is too far off the pulley face then this would cause poor cooling as it would slip and wear out faster. there is a spec for the clutch gap.
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