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I have been dealing with a nagging issue after the restoration of my cutlass where when I select heat I do not get any heat at all. I installed a new heater control valve from a local parts store years ago. I finally decided to see what’s wrong and it appears I have a faulty or wrong heater control valve. Using this forum to search I found when I pull the vacuum line off the valve it opens and I get heat, both hoses are warm.
1969 cutlas s convertible w a/c. What valve do I need?
here is pic of valve currently on car
Your car came with a valve that is normally closed and opens when vacuum is applied. Nearly every vendor incorrectly lists newer valves for this application. The newer valves work backwards - normally open and close when vacuum is applied. Olds change the valve on the full size cars for the 1971 model year and on the A-body cars for the 1973 model year. If the source you are looking at lists the same valve P/N for newer cars as well as yours, run, don't walk, away.
I noticed on opgi website they list one valve for manual control a/c and another for heater/ac w atc.
what is atc?
I have no idea what "ATC" is. There was only one type of A/C offered on the Cutlass line, the manual control A/C (full size cars and Toros offered the optional Comfortron automatic A/C, but not the Cutlass line, and the valve is the same in any case). The fact that they can't even get this right suggests that they are clueless and likely won't have the correct part listed.
Automatic Temperature Control or comfortron systems have a temperature operated vacuum switch in the top to turn the system on in the "LO" and "High" settings once the engine temp reaches a certain range.
Automatic Temperature Control or comfortron systems have a temperature operated vacuum switch in the top to turn the system on in the "LO" and "High" settings once the engine temp reaches a certain range.
Actually that's correct through the 1970 model year. The later cars used a temp sensor that screwed into a fitting on the top of the valve and the same P/N was used for both. It's still irrelevant for the OP's A-body, however.
As Joe said, comfortron was not available on the A-body line-up. I assumed OPGI was listing it for other models as they now sell large body and Caddy parts as well, but looking at their site, I see the have an "ATC" valve listing for cutlass "61-77". As Joe said, assume it is an incorrect listing.
I see the have an "ATC" valve listing for cutlass "61-77".
Wow! That's really screwed up.
The 61-63 valve is completely different, and is actually used to control temp for the heater by proportionally regulating coolant flow though the core. It has nothing to do with A/C. This is a 1961-63 valve. That should tell you about the accuracy of their application info.
Along with ensuring you get a valve that works correctly for your vacuum source, make sure the threaded fitting is the right size. The early (1970-older) intake manifolds use a smaller fitting whereas the later (71-up) use a larger fitting.
Last edited by Fun71; January 5th, 2022 at 03:52 PM.
I found a four seasons brand #74601 that cross references w part #
I hope that works. I’m just glad that’s all it was. Immediately after I turned on heat and disconnected vacuum I got heat in passenger area.
January 5th, 2022, 12:22 PM
