another AC question
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Joined: Apr 2007
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From: michigan
another AC question
89S4 the two center vents outside cool air coming through top vent. Hot air comming through the bottom vent. With A/C on cold through top vent warn air coming through bottom vent. Heater valve?
Three Wheelin'
Joined: Sep 2003
Posts: 1,526
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From: SF Bay Area
Not necessarily. The heater valve is the first thing to check.
Remove the air cleaner and push the slide all the way to cold - the micro switch should click. Look at the heater valve and have some one slide the selector to hot. Be sure to have the bottom slide selecting some position other than off. The heater valve should open. If not then that is the place to start.
A MityVac is a good tool to have. About $20 at Harbor Freight. With the engine off, disconnect the heater valve and connect the MityVac. Pull a vacuum and see if the valve both moves and holds the vacuum. If it does the valve is good. You might check the rest of the fitting while you are in there.
Next pull the left side panel below the center console. Locate the orange tube. Disconnect it and apply a vacuum to the end going under the console. You should hear movement in the center vent and the gauge should hold a vacuum. If not your center flap actuator is bad.
Other things to check are the cabin sealing. Heat can come up from the center console through the shifter. I used a little spay foam insulation to seal that one up. Be careful not to use too much.
There is a gasket on the fire wall that mates to the hood. Often this one is missing. If it is the engine heat blows into the HVAC system flooding it with heat and defeating the A/C
Look for holes into the cabin from the firewall. They can blow in a lot of heat and override a good A/C output.
Before I sealed up my cabin on the 85 I had to run the A/C at full blast and even then I was hot on relatively mild days. After sealing it the A/C blows cold on the lowest setting and I have to keep bouncing back and forth between no fan and position one - even on very hot days and in traffic.
There could be other issues, but these are the first things to check. A lot of heat can get into the system without coming through the heater core.
Good luck
Dan the Pod Guy
Remove the air cleaner and push the slide all the way to cold - the micro switch should click. Look at the heater valve and have some one slide the selector to hot. Be sure to have the bottom slide selecting some position other than off. The heater valve should open. If not then that is the place to start.
A MityVac is a good tool to have. About $20 at Harbor Freight. With the engine off, disconnect the heater valve and connect the MityVac. Pull a vacuum and see if the valve both moves and holds the vacuum. If it does the valve is good. You might check the rest of the fitting while you are in there.
Next pull the left side panel below the center console. Locate the orange tube. Disconnect it and apply a vacuum to the end going under the console. You should hear movement in the center vent and the gauge should hold a vacuum. If not your center flap actuator is bad.
Other things to check are the cabin sealing. Heat can come up from the center console through the shifter. I used a little spay foam insulation to seal that one up. Be careful not to use too much.
There is a gasket on the fire wall that mates to the hood. Often this one is missing. If it is the engine heat blows into the HVAC system flooding it with heat and defeating the A/C
Look for holes into the cabin from the firewall. They can blow in a lot of heat and override a good A/C output.
Before I sealed up my cabin on the 85 I had to run the A/C at full blast and even then I was hot on relatively mild days. After sealing it the A/C blows cold on the lowest setting and I have to keep bouncing back and forth between no fan and position one - even on very hot days and in traffic.
There could be other issues, but these are the first things to check. A lot of heat can get into the system without coming through the heater core.
Good luck
Dan the Pod Guy
