1976 vette ac system questions
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Joined: Jan 2007
Posts: 82
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From: Portsmouth Virginia
1976 vette ac system questions
Ok I have a 76 late production with the R4 style AC system.
1. Does this system have a low pressure switch?
2. Has anyone had any luck switching to 134 with this system?
My old sytem has not worked in quite a few years but it does still hold some pressure so the system has not been open to the outside air. I unpluged the comp not knowing if it would run hot without enough R12.
I switched my 71 buick to 134, very simple process and still blows 41 deg all day long. It does have an older A6 comp however.
I have all the parts needed to switch and I might start today.
1. Does this system have a low pressure switch?
2. Has anyone had any luck switching to 134 with this system?
My old sytem has not worked in quite a few years but it does still hold some pressure so the system has not been open to the outside air. I unpluged the comp not knowing if it would run hot without enough R12.
I switched my 71 buick to 134, very simple process and still blows 41 deg all day long. It does have an older A6 comp however.
I have all the parts needed to switch and I might start today.
Race Director
Joined: Apr 1999
Posts: 11,520
Likes: 13
From: CORVETTE 77 385 C.I. TEXAS
Look for a pressure switch near pass. fender in the line from condensor & below sight glass & service port.
Did you replace the orifice tube for 134?
Some A/C shops are changing the GM white orifice tube .072 to the Ford blue .067 mainly because of 2 O-Rings to seal better
& which is smaller -7%.
Some factory systems were converted from R-12 to R-134a by only reducing the orifice tube as much as 16.6%!
Probably changing the GM white orifice tube .072 to the Ford red .062 would be better (-14%) & is what I would do if changing to 134a today. GM yellow .062 would also work.
Did you use POE oil- some 134 have oil in them but don't say which one.
Did you replace the orifice tube for 134?
Some A/C shops are changing the GM white orifice tube .072 to the Ford blue .067 mainly because of 2 O-Rings to seal better
& which is smaller -7%.
Some factory systems were converted from R-12 to R-134a by only reducing the orifice tube as much as 16.6%!
Probably changing the GM white orifice tube .072 to the Ford red .062 would be better (-14%) & is what I would do if changing to 134a today. GM yellow .062 would also work.
Did you use POE oil- some 134 have oil in them but don't say which one.
