Remove your Radio.
Remove your Fascia Panel on the heater controls.
See if your arm is out of place to the hot/cold slider.
To fix it.
Carefully remove the Pivot arm off the thermoswitch Remove the screw that holds the switch on.
PUSH the switch shaft down to free the arm.
Once you have the shaft free select a washer that will go over the post of the thermoswitch and sit flat on the plastic.
Replace the Pivot Arm over the shaft for the thermoswitch and position it so it is in the run of the hot/cold slider.
You have just shimmed the Pivot arm to be closer to the hot/cold slider so it shouldn't "pop" out of place. Clean the things up and lube the arms and such with white lithium grease or your favorite light grease, and you should be good to go.
BE-WARNED that Thermoswitch is NLA, so go easy on it, if you "Person-Handle" the control you can break it. Besides being NLA it is Pricey.
