A/C question
Thread Starter
Racer
Joined: Dec 2007
Posts: 445
Likes: 2
From: Thomastown Mississippi
A/C question
I recently reworked the a/c in my '77. New compressor, dryer, filter, etc. It actually cools very well, but I have noticed that when you have the a/c turned on, the compressor seems to run constantly. Is this normal for these old cars? The reason I ask is that I notice on my newer trucks that the compressor seems to constantly cycle on and off when the air is on. I thought maybe I've got a bad switch or relay somewhere, or maybe it's nothing. What say you a/c experts??
KC
KC
Advanced
Joined: Nov 2005
Posts: 86
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From: Parrish Alabama
I'm no expert but the older sysyems with R-12 ran all the time to keep cool. The newer systems have a cycling clutch system. There is a VIR assembly in the older systems that can be replaced with a VIR eliminator that will turn your system into one that cycles. It is what I am going to use on my 76 when I redo it. The even older systems used a POA valve that could be replaced to make the system cycle. The valve runs around $160 I think.
Racer
Joined: Apr 2006
Posts: 340
Likes: 0
From: Warrensburg MO
I think it depends upon if you have an early or late 77. Mine is a late 77 that has the orfice tube design. If you have an orfice tube, it should cycle. With yours staying engaged, and not freezing up, I will assume yours doesn't have the orfice tube.
TommyJ
TommyJ
Drifting
Joined: May 2005
Posts: 1,629
Likes: 4
From: Somers CT
These compressors run all the time, in short, the VIR cycles the cooling system requirements to keep it from over cooling or freezing up. Converting one to a cycling system may be very annoying, the compressor can draw up to 5hp in full demand, when that cycles on and off it'll drive you nuts. The newer style compressors with the newer A/C designs require very little to run so when they cycle you can hardly notice it.
