[msmith65]

'97 Sable GS

Turning the hot/cold dial on the dash has no effect on AC vent temperature. It just blows freezing cold. The compressor cycles OK once the car is cold inside.

Also, switching on the heater produces no heat, just ambient air from the vents.

I can't imagine this is anything but a faulty controller behind that dial, but before I tear into the dash I hope one of you has some guidance -- maybe it's something simpler?

 

[01SE]

How's your temperature gauge? Does the needle sit right in the middle or does it fluctuates, once the engine warms up? If it fluctuates, you might need a new thermostat. Did you try to feel the hoses that go to the heater core? If one hose warm and the other is cold, you might have plugged heater core.

 

[901-Memphis]

If your temperature gauge is normal usually its related to the blend door

 

[machineop]

One way to tell if your blend door is functioning normal is that you can here it move as you move the temp dial from cool to heat. If you dont hear anything then it probably broken. Its also an esay fix.GOOD LUCK!

 

[msmith65]

AC temp control is also absent. Thermostat and blend door don't prevent me from raising AC vent temp with the dial.

 

[james27613]

hi,

please check the heater core hoses at the firewall,
use caution, it it hot back there.

You can run the car for a few min and then turn it off to check.

the temperature of each of the hoses should be about equal,
if one is hotter and the other is just warm you have a blocked
heater core.

regards

 

[sheila]

Check blend door actuator motor behind the radio and ashtray. Easiest way is to remove radio football oval with din keys and then test by rotating the cold-hot knob.

 

[jacary27]

If you see the arm for the blend door going up and down does that mean it is actually working? Of could there be something behind the actuator that is broke.

 

[sheila]

You should be able to see and hear it rotating a short distance, not moving up and down. Dunno. Could be a prob. with the blend door itself? I am talking about the actuator rotating.

 

[msmith65]

Why would any of this prevent me from modulating the AC vent temperature?

 

[sheila]

Compressor runs in every position except vent, floor and off. Coolant is always running through the heater core. Only way temp. is controlled coming out of vents is with the hot-cold control knob which activates blend door actuator which opens and closes blend door(s) depending on temp. setting selected.

 

[sheila]

Compressor may even function in vent mode, i cant remember.

 

[msmith65]

Compressor runs in every position except vent, floor and off. Coolant is always running through the heater core. Only way temp. is controlled coming out of vents is with the hot-cold control knob which activates blend door actuator which opens and closes blend door(s) depending on temp. setting selected.

Thank you for that.

So, dialing the temp control down (from coldest) doesn't affect the compressor cycling?

Seems like it used to.

 

[sheila]

The temp. selection is controlled electrically. The mode (vent, floor, off etc.) selection is controlled by vacuum.