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George H.
George H., ASE Certified Technician
Category: Chevy
Satisfied Customers: 18441
Experience:  GM Tech ASE Master Tech 15+ years
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Chevy lmpala: What should head pressure be on 134a

Customer Question

What should head pressure be on 134a for air
Conditioning
Submitted: 1 year ago.
Category: Chevy
Expert:  George H. replied 1 year ago.
Hello I will help you with your question, There are a lot of variables here so pressure is not a good gauge of how much is in the system but on a properly operating system you will expect to see 180 - 230 psi on the high side when the compressor is running. If the compressor is not running and the system has stabilized the pressure should be close to air temperature. Please let me know how I can help Thank you
Customer: replied 1 year ago.
After 30 minutes. Suction is 18 and high side is 120 added 2 14th cans ?
Expert:  George H. replied 1 year ago.
I don't know what system you are working on? Year and engine size please
Customer: replied 1 year ago.
1966 chevy 327
Expert:  George H. replied 1 year ago.
So its converted and using an R12 compressor?
Customer: replied 1 year ago.
R134
Expert:  George H. replied 1 year ago.
I don't understand that.
This has the original compressor or was the compressor changed over to R134 style? Is this an original system or is it an aftermarket add on?
Customer: replied 1 year ago.
Compressor converted to 134
Expert:  George H. replied 1 year ago.
OK, this system holds 3 pounds 12 ounces of R12 and you want to add about 75% of that when you add 134a. If the system was empty when you started (meaning under vacuum) then you have about 1.5 pounds in, add the same amount again (no sealer, dye and maybe 1 can with an oil charge) and see how it cools.
Let me know how I can help
Thank you