Climate control problems? Read This!

[gadget73]

90 may or may not be vacuum actuator. They changed to electronic controls in the late boxes, pretty sure 91 was electronic, I think '90 may be as well. If it is, none of the vac stuff applies.

Honestly that sounds more like low coolant or some sort of restriction in the core. A vacuum leak won't cause it to do that.

[over2tonsofFun]

It is now barely putting out any heat. Even at highway speeds. Coolant level is up. Any other ideas?

Thanks
Tim

[gadget73]

blend door not moving fully to hot or clogged heater core. Assuming the engine comes up to a decent temp.

Clogged core is easy to check. If one hose is hot and the other is cold, its not moving any water. Both should be pretty hot. If neither are hot the engine isn't coming to temp or the core is so clogged water won't even move through it.

[sly]

Could also be dirt/dust/mud/grime clogging the fins of the heater core and not allowing flow through it.

[clutch47]

Excellent info. Thank you.

[gadget73]

if the fins are packed with dirt it won't move much air through the vents.

[over2tonsofFun]

It wound up being the whole control unit. replaced it works great now.

Tim

[aharonLTC]

When driving and I steer the vehicle around a left turn ATC blows hot, around a right turn the ATC blows cold - I'm guessing bad AATS sensor or the blend door has separated from the line since it's switching hot/cold based on vehicle steering? Haven't dug into it yet since I usually just ventilate with the windows down.

On my car I've plugged off the parking-brake release vacuum line since the switch leaked. I wonder if I could repurpose that line to the blend door with my own valve to control hot/cold.

[gadget73]

be easier to just use the existing line to the temperature controller, but replace the temp control with your own valve. If you pull the top of the dash off you'll find the whole works there, cable from the slider, vacuum line in, and vacuum out to the servo. Connect those bits up as appropriate and you can control the door without having to drag a hose from one side of the car to the other.


If the temp flops with steering, might just be the servo somehow got unhooked. If I remember right that door is welded to the actuator rod so while not impossible for it to have broken loose its not the first thing I'd suspect. On the top side though I think the arm comes out in roughly a Z shape and the arm of the vac servo just slides over it. I think there is a push clip of some fashion on top of it to hold it all together. If that popped off you may have the vac servo arm not connected to the blend door arm. Should be able to get a mirror or something in there to see whats going on.