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On a recent nice 65 deg day I was driving my 66 (small block)with AC with both the ac and heater off. The temperature in the AC duct on the driver side was 85 deg. I am reasonably sure my heater shut off valve is completely closed. Is it reasonable to expect this much heat from the engine compartment soaking thru?
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Re: C2 with AC question
Randy,
To completely cut off the hot water you would have to have two (2) cut off valves. That may sound a little off key and I thought so also, but I installed an "Old Air" AC in my 66 BB and asked the company about the two valves they supplied with the kit.
The "Old Air" box does not have a flapper door to separate the AC coil and the Heater coil so they used two valves to completely shut off the hot water thereby saving money and simplyfing the system.
The Corvette box has the flapper door and with one valve it is adequate to stop the hot air from mixing with the cold side.
As your system approaches it's 39th birthday, what do you think of the condition of the flapper door in your AC box. After driving for a time the water will warm up and the flapper door leaks and there you have your 85 degree air coming from the AC.
Your old baby needs some attention or you can put a couple of valves in the heater lines and stop the flow of hot water completely.
Regards,
JR -
Re: C2 with AC question
I am experiencing the same problem with my 1964 a/c coupe blowing warm air through the a/c vents. I replaced the heater control valve and it helped some, but warm air is still blowing through.
JR poses an interesting question. I guess I do not completely understand the system. I assumed that the heater control valve completely restricted ALL hot water from entering the heater core thereby eliminating the heater as a source of the unwanted hot air in the vents. Is it true the heater control valve actually only stops the FLOW of water through the core, but some hot water still reaches the core?
JR, which 2 hoses are actually blocked off? The ones going to/from the heater core? To properly fix the system, sounds like the flapper door needs some work. True?
Thanks!Comment
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Re: C2 with AC question
Bruce,
I think you have a great understanding of the system. To completely block off the hot water you would have to have a valve in both hoses going to the heater core. The flow is stopped with one but after continued heating the water in the other hose still gets hot and migrates into the core.
GM put the flapper door in to seperate the heater core from the AC core. Great idea and expensive to do it this way but as the old flapper rubber and door get 39 years old it doesn't exactly seal completely.
Regards,
JRComment
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Re: C2 with AC question
I happen to have another control valve laying around. I might just hook this second valve up the other heater hose and install a tee-fitting to connect the vacuum hose from the heater switch to both valves. Should work fine until I have a chance to pull the air box and replace the rubber flapper to bring everything back to factory spec's. Or, I could just whip out my handy hose crimper tool and crimp off the second hose until the weather gets cold again.Comment
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Re: C2 with AC question
My C2 roadster has a shut off valve in both heater hoses to completely restrict
all hot water flow when they are closed. I found this out when the weather got cold and no heat was available. By the same token, when the weather warms up, the inside of the car gets very warm until the valves are closed. Seems to work great to compensate for heat migration. My flapper control has been rendered inoperable by whoever made the "upgrade"-probably the door is wired or screwed closed. I recommend the conversion.Comment
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Re: C2 with AC question
J Ray and Bruce,
Thanks for the input. J Ray I think you are right now that I think about it. I was assuming it was engine compartment heat but even if the hot water INLET valve is closed I guess hot water eventually reaches the heater core through the outlet hose. Peeking into midyear engine compartments I have noticed some with small gate valves installed in the heater hose lines and assumed it was because the heater core leaked.
Since I am trying to maintain an original appearance I guess I'll have to live with it or repair the flapper seal. Thanks again for the tipComment
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