RED DOG, he has posted the symptoms and checked the coils already, they are not stuck open and the coils are showing continuity. Swampotter, the slight warm lines are a good sign, now lets turn the dials to max cool setting, turn on the fan, and start the car (after the car cooled down completely cold). Don't push the A/C button, leave it off (no need to), wait until the car is warmed up and feel the zone lines (the two lines going to the duovalves where they exit the firewall behind the passenger side shield. Those two lines should not be hot. Without changing any settings, feel those valves while the car is running (based on the zone temp dial set to max cool and fan on), you should not feel the 'thump' of the valves. If you move the temp dials to any other setting on either zone, and they are cycling (it is a pulse, they cycle on/off rhythmically), that respective 'zone valve' will pulse and the line associated with that zone will get progressively hot. Unfortunately it takes time to determine if the valves are shutting off 100% because it takes time to 'bleed' off the heat after they circulate hot coolant (which is why we want START with the dials first set to max cool with fan running, if they are 'leaking' internally one or both will get hot). Feel those two valve bodies (the duovalve) while checking the two zone lines at the firewall behind that shield, make sure those two valves are not 'pulsing' at all (you can feel when they do). If they are, it is getting a signal to cycle and no replacing of the valves will fix this. One MUST remember that this issue is intermittent, which again leads me to the systemic problem with the control head. Throwing parts at it (especially USED parts) is not a sound program to follow. I believe Dave (180) lists that control head .pdf in his huge list of help fixes, that fix costs almost nothing, and may solve this intermittent problem. Lets keep focus on determining if the valves are shutting off 100% when not commanded to open, ok?


If the whole system failed and you start the car cold, you'll have no heat, period. Not sure what you meant, am having a senior moment here trying to understand what your trying to say.

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