AC Compressor Pressure Switch
Thread Starter
Disabled by request 8 JUN 2025
Joined: May 2019
Posts: 329
Likes: 94
From: St. Augustine, FL
AC Compressor Pressure Switch
Following a 134a recharge and in an effort to possibly increasing my 81's AC output I thought I would try the "1/8 CCW turn on the compressor pressure switch". allowing a longer compressor cycle. Unortunately my switch does not allow this mod. I see there is a pressure switch for 134a. My question is, can I replace the compressor pressure switch without dumping the refridgerant, or is there a check valve allowing the switch replacement without loosing the charge?
Instructor
Joined: Oct 2021
Posts: 209
Likes: 33
I just done a kit on my 73. It came with a switch and the drier thing. That's it. And you lose the gas changing it. As for your pump. The 81 s must be real different because on a 73 the pump never turns off if a/c is on. It's always on. I know my modern cars all cycle, this is the first a/c I've ever seen were the pump does not shut off. I also just discovered the reason mine was a bit weak was because I put too much gas in it. Had 70psi, dropped to 45 and it's ice cold now.
Thread Starter
Disabled by request 8 JUN 2025
Joined: May 2019
Posts: 329
Likes: 94
From: St. Augustine, FL
I can feel my compressor cycling on and off, infact it's somewhat annoying hearing it. I have reason to believe that it should stay engaged longer. Right now it's engaged for maybe 5-6 seconds before it turns off and maybe the same amount of time off before it engages again. The AC cools adaquately, it's just that it may cool better if the compressor stayed engaged longer. Am I right ??
Safety Car
Joined: Oct 2007
Posts: 4,380
Likes: 1,740
From: Seattle Area Washington
I can feel my compressor cycling on and off, infact it's somewhat annoying hearing it. I have reason to believe that it should stay engaged longer. Right now it's engaged for maybe 5-6 seconds before it turns off and maybe the same amount of time off before it engages again. The AC cools adaquately, it's just that it may cool better if the compressor stayed engaged longer. Am I right ??
Yes, you will need to evac the system and recharge if you open it...
To me you have a pressure issue...
You really need the service manual and a set of gauges so you can follow exactly when the pressure cycling switch is on or off and compare those findings to what the service manual says ...
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