Automotive Air Conditioning Information Forum (Archives)

Dave in Texas on Mon August 27, 2012 9:20 PM

Year: 1987
Make: Cadillac
Model: DeVille
Engine Size: 4.1L
Refrigerant Type: R134 convert

I rebuilt the AC system back in '98 and converted it to R134. Installed a new DA6 compressor and system has been cooling well until about a year ago. I put a can of 134 w/dye and see the compressor is leaking. 14yrs is good for me. It being only assessable from under the engine is no fun at all.
I'm curious what differences there are in the DA6 and the HR6 compressors? DA is specified, but if the HR is a better choice....
I intend to go back to R12, mainly because I know what the pressures are for the R12. I've never been 'comfortable' guessing with the 134 refrigerant pressures.
I've got everything needed except a replacement compressor, so I thought I'd ask about the different models. Thanks

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At 2, I went home with a 10. At 10 I woke up with a 2 !!

GM Tech on Mon August 27, 2012 11:01 PM

Da-6 uses no reed valves on end of pistons- there is a separate valve plate- HR (and HT) -6 use the flow through design- where the oil flows much better through the internals of the compressor- and they have the suction reed valves on each end of the pistons. Along with that- there is no such thing as a new DA-6 since the HR-6 replaced it and backfilled all service models- the HR-6 uses new improved castings- thicker for sound and vibration abatement.....so if you are going to use a Da-6 it must be a used one or some old new stock-- also Da-6s were widely known for shredding their piston rings due to lack of flow through lubrication which came in with the HR-6...

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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

Dave in Texas on Tue August 28, 2012 10:55 PM

Thank you for the information. The DA would be a rebuilt piece. As you said, I've not found a new DA, only rebuilts. I'll most likely go with a new HR.
I appreciate the response, thanks.

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At 2, I went home with a 10. At 10 I woke up with a 2 !!