# Car A/C compressor clutch not engaging?



## Windows on Wash (Aug 30, 2011)

Any noise out of the compressor prior to this? Have you checked the book for high and low side values and ranges? 



Voltage to the clutch?


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## ElectricIQ (Apr 12, 2019)

Did not notice any noise. It just stopped working after the winter (except on rainy cold days). I think ~100 PSI on both sides indicates compressor not engaging (but it does on those days?)... could this be a sensor issue?


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## Bigplanz (Apr 10, 2009)

Same pressure on both sides means the system has equalized. The compressor comimg on lowers the low pressure side, raises the hi pressure side and cycling from low to high cools the car interior. Try jumping the low pressure switch. If it is defective the compressor won't come on. Same with the high pressure switch, but it rarely goes bad. Try sending 12v straight to the clutch, see if it engages.


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## raylo32 (Nov 25, 2006)

You can also try jumping the relay to try to energize the clutch to test it.



Bigplanz said:


> Same pressure on both sides means the system has equalized. The compressor comimg on lowers the low pressure side, raises the hi pressure side and cycling from low to high cools the car interior. Try jumping the low pressure switch. If it is defective the compressor won't come on. Same with the high pressure switch, but it rarely goes bad. Try sending 12v straight to the clutch, see if it engages.


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## Oso954 (Jun 23, 2012)

> What could be my problem? is my compressor bad? but then why would it work in rainy cold weather?


Most likely you have the Defroster turned on during that cold rainy weather.

Having AC air mixed with heater air for defrosting, helps dry the air/defrost quicker/reduce or eliminate condensation on the inside of the windows.


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## Brainbucket (Mar 30, 2015)

Almost sounds like too much air gap between clutch and hub. A cheap way to check this is, engine running, A/C on and take a piece of wood and tap the clutch. If it's too much air gag, it should engage. Be careful as it can screw up and you'll have a piece of wood flying around the belt area. Check for voltage at clutch connector. The gap should be around .020 :vs_cool:


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## Tymbo (Jan 18, 2018)

It might be a simple shim on the clutch. My CRZ compressor was not engaging and I removed a shim and all is good again. It was 15 minute job. YouTube is your friend.


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## ElectricIQ (Apr 12, 2019)

Thank you all, good ideas. I will do more testing.


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## huesmann (Aug 18, 2011)

Oso954 said:


> Most likely you have the Defroster turned on during that cold rainy weather.
> 
> Having AC air mixed with heater air for defrosting, helps dry the air/defrost quicker/reduce or eliminate condensation on the inside of the windows.


But if the compressor isn't working during dry weather, it shouldn't be working during wet weather. If the compressor isn't engaging, there is no "AC air" to mix with heater air.


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## raylo32 (Nov 25, 2006)

LOL... sounds like what we had to do with my college roommate's VW bug... bang on the starter solenoid to get it to engage. Usually worked like a charm but maybe not so much when trying to make a getaway from a motel with a garbage can of ice for a kegger... and the maid running after us. ;-/ Those were the days.



Brainbucket said:


> Almost sounds like too much air gap between clutch and hub. A cheap way to check this is, engine running, A/C on and take a piece of wood and tap the clutch. If it's too much air gag, it should engage. Be careful as it can screw up and you'll have a piece of wood flying around the belt area. Check for voltage at clutch connector. The gap should be around .020 :vs_cool:


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## ElectricIQ (Apr 12, 2019)

Thank you all, finally found the root cause and fixed it today, thanks to this guy:


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## ElectricIQ (Apr 12, 2019)

Brainbucket said:


> Almost sounds like too much air gap between clutch and hub. A cheap way to check this is, engine running, A/C on and take a piece of wood and tap the clutch. If it's too much air gag, it should engage. Be careful as it can screw up and you'll have a piece of wood flying around the belt area. Check for voltage at clutch connector. The gap should be around .020





Tymbo said:


> It might be a simple shim on the clutch. My CRZ compressor was not engaging and I removed a shim and all is good again. It was 15 minute job. YouTube is your friend.



When I first read these, they only made half sense to me, and it turned out to be exactly what was wrong with mine, thanks!!


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## Fixin_cars (Mar 10, 2021)

ElectricIQ said:


> Hi, my car (Honda Fit 2010) A/C's reading 93 PSI on the low side and 100 on the high side when car's off. Then when car engine's started (AC off), low side drops to 85 PSI and high side to 90 PSI. Switching AC button has no effect on pressure, and I could see compressor not spinning.
> 
> 
> Some background: intermittent A/C in 2016/2017, added freon using a low side only gauge in 2017, filled up from 25 to 35 PSI in 70 F temp, A/C worked again for a year. Became intermittent again in 2018 (only worked on colder days, or when car was cold started), low side read 45 PSI when it worked, so I did not add freon. I changed the clutch relay switch to no effect. Now in 2019, it does not work at all unless it's raining with temps in the 50s F.
> ...


Add some freon again and see if you can get the compressor to come on at all


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## LawrenceS (Oct 21, 2020)

Fixin_cars said:


> Add some freon again and see if you can get the compressor to come on at all


You do notice the 2 a/c threads you replied to are 9 months and 20 months old and whatever the issue was has most likely been resolved one way or another since the original posters have not keep the threads going.


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## Fixin_cars (Mar 10, 2021)

LawrenceS said:


> You do notice the 2 a/c threads you replied to are 9 months and 20 months old and whatever the issue was has most likely been resolved one way or another since the original posters have not keep the threads going.


Sorry you're right my bad


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