HEATING AND AC PROBLEM
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Pro
Joined: Sep 2000
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From: clovis ca usa calif
HEATING AND AC PROBLEM
When I turn on my defroster it comes out of the ac vents. When I turn on the ac, it comes out of the defroster vents and ac vents. Also with the fan on high, it doesn't blow very hard. Last summer I replaced the ac compressor. Whats the solution? Thanks, James holley in Clovis Ca
Le Mans Master
Joined: Dec 2000
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From: San Diego, Ca
Re: HEATING AND AC PROBLEM (james holley)
Somewhat depends on whether it's electronic or manual air. For manual, the dash controls vent position by blocking and opening vacuum ports for the air door solenoids. For electronic, the programmer above the accelerator does it electronically based on electrical signals from the dash. Have you swapped out either? Both methods use the same color codes for the vacuum harness. The defrost solenoid should have a red vacuum hose on the top, and a tan on the side. The a/c solenoid is the dark blue hose; the heater solenoid a pink hose and outside air valve is an orange hose. I think it would be fairly difficult to get these hoses switched around if your Vette has electronic air. The vacuum harness is indexed to the programmer as is the electrical harness. I don't know about the manual control but with either system, I think you probably want to confirm that the right hoses are going to the correct solenoids first, and if its, Manual Air, I'd remove the dash control and see what color is hooked up to each position. If the colors are right, then something in the controls is funky. As to the fan, it again depends on the system, but a quick test is to jumper it directly to the battery to see if it runs any faster.
Drifting
Joined: Jan 2002
Posts: 1,606
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From: Las Cruces NM
Re: HEATING AND AC PROBLEM (james holley)
Usually the problems you describe are caused by vacuum issues. There's a line that comes off the manifold(if you've got an L98 car) from one of the two vac ports at the rear of the upper plenum. Follow this accross in front of the distributor and it goes to a vacuum regulator. Once outlet from the reg goes to the hvac system and the other goes to the cruise control module. If there's a leak or if it's not even plugged in, your hvac stuff will act just as you described.
Most times it's just the vac line got unplugged from the regulator. If your cruise control doesn't work as it's supposed to, or at all, it's the line from the regulator to the manifold or the regulator itself. The regulator looks like a little plastic cylinder with 3 vacuum lines going to it.
Chris
Most times it's just the vac line got unplugged from the regulator. If your cruise control doesn't work as it's supposed to, or at all, it's the line from the regulator to the manifold or the regulator itself. The regulator looks like a little plastic cylinder with 3 vacuum lines going to it.
Chris
Le Mans Master
Joined: Dec 2000
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From: San Diego, Ca
Re: HEATING AND AC PROBLEM (okinawa86vette)
Generally if the source is bad, all you get is defrost and nothing else - that's because the defrost doors have vacuum applied to them at all times by default (that vacuum has to go somewhere; so GM decided to use it on the defrost doors). Even when defrost is requested, vacuum is applied to the opposite side of the solenoid, that's why there's two hookups, but if there's no source at all, the doors flop wide open and you won't have anything to open the a/c or heater doors either so they stay closed.
