Hey guys is it necessary to have a heater valve? Do i have to have vacuum to my A/C control unit for my heater to work?
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Heater Valve Question?
- Thread starter pjpj1979
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pjpj1979 said:
The heater valve is a normally open valve that only closes when the A/C is on the Max Cold position. It is not necessary for the heater (or even the A/C) to function. You do need vacuum to the control head, however, since the various doors in the HVAC box under the dash are vacuum controlled. These doors divert the air from floor to vents to defrost. Without vacuum, the system defaults to a combination of defrost and floor airflow. Note that the temp control door is cable operated, not vacuum.
The heater valve is in the heater line going to your heater core that you open and close to varying degrees depending on the amount of heat you want in the car and it's controlled by vacuum......if you don't have a heater valve and the heater lines are still hooked up then you'll have constant hot air blowing inside the car
I used to have a 79 monza with no valve. And it got damn hot it there is the summer. I tried unplugging the fan, that helped a bit. I eventually just started bypassing the heater core in the summer because I was roasting in that thing. But, that was my first car, and I didn't know about those valves lol.
pontiacgp said:
Sorry, but you are incorrect. Read my post above, or better yet, a factory Chassis Service Manual. The heater valve ONLY closes when the A/C is on Max to get the most cooling. At all other times, it is fully open.
here is a heater valve.....and as you can see there is a fitting for a vacuum line on the top to adjust the valve opening
http://cgi.ebay.com/ebaymotors/HEATER-V ... 0001r15534
http://cgi.ebay.com/ebaymotors/HEATER-V ... 0001r15534
it doesn't matter what motor your using...it depends on what controls the heater valve, most operate by vacuum
I understand that, my operates on vacuum as well but is there a heater valve i can use besides the one that was on my 307? My fittings on my eldebrock intake are different from my 307 intake. I can't use the stock heater valve.
There are aftermarket valves available that operate with cables from inside the car, or that even have to be turned by hand under the hood.
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