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sprinkles08
sprinkles08, ASE Certified Technician
Category: Car
Satisfied Customers: 23126
Experience:  ASE Master and Advanced level certified. Factory trained with 17 years dealership experience
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Buick Regal GS: 97 regal auto climate control. ac was working

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97 regal auto climate control. ac was working but compressor had a leak. replaced compressor, dryer, condenser, and pressure switch. recharged system but now the compressor will not kick on.

Hello and welcome to JustAnswer!

 

If the system was working ok before this components were replaced and it has been charged to the proper level (1.88 pounds) then the most likely cause for this would be the pressure sensor or connection. The compressor is obviously ok since you can jump the relay and it will run, if it will run when the relay is jumped then you know the compressor isn't being commanded on. If the pressure sensor signal is missing or out of safe operating range then the powertrain control module won't allow the compressor to engage.

 

This is a sensor rather than a switch so it's not something that can be jumped. If you have a scan tool you can compare it's pressure signal to what is shown on a manual gauge set to see if it shows the same. If you don't have a scan tool I would install the old pressure sensor if you still have it and then see if the compressor will engage.

 

If the system isn't properly charged that will prevent the compressor from engaging on it's own. I see that you said it is charged so I'm assuming it's at the proper level, but if it's low then that could be the reason the compressor isn't engaging.

 

 

Customer: replied 4 years ago.

how can i verify the control head is working properly and sending the right signals? which wire do i check and does it send power or ground?

There isn't a single wire you can check for an a/c request. The control head sends the a/c request over the data bus to the powertrain control module (PCM), the PCM then turns on the compressor if a/c pressure is correct. To verify that the control head is commanding the compressor you'd need to use a scan tool to look at the data.
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Customer: replied 4 years ago.

I checked it with a scan tool and it said AC request NO.

The problem is most likely going to be the control head then.


Customer: replied 4 years ago.

Can this be converted to the manual system?

It could be done but I doubt it would be cost effective. I'm not where I can access my GM parts information this morning and would have to check to make sure, but converting to a manual system most likely would require replacement of the heater box and dash wiring harness along with the control head.
Customer: replied 4 years ago.

can the refrigerant pressure sensor cause the scan tool to show no request for AC or does it read it directly from the control head? i replaced it thinking it was not cutting off the compressor in time and causing too much pressure then blowing out the shaft seal. i hate to spend the money for a control head and still have the same problem.

Customer: replied 4 years ago.

can the refrigerant pressure sensor cause the scan tool to show no request for AC or does it read it directly from the control head? i replaced it thinking it was not cutting off the compressor in time and causing too much pressure then blowing out the shaft seal. i hate to spend the money for a control head and still have the same problem.

The pressure sensor is actually wired to the PCM and the PCM monitors it and then decides whether to run the compressor, bump up the idle and run the cooling fan.
Customer: replied 4 years ago.

What about compatibility of the control heads. I've been reading articles that say the numbers need to match exactly and others that say it doesn't mater.

The part number would need to match between the original and replacement.