I've been chasing some issues on the SDL lately and came across two sensors that feed the PBU:

The evap temp sensor

The cabin temp sensor

Now, what is interesting is that I always assumed that the evap temp sensor was the device that regulates the compressor. If the evap temp gets too cold, the PBU dumps the compressor. Makes sense.

However, the evap temp sensor was found to have a resistance of 2.2K at ambient temperature without the system running. This is far below the specs of 5.5K for this temperature. So, clearly, the evap temp sensor is not regulating the compressor, otherwise the a/c would never work correctly with this much of a deviation in the resistance in the thermistor.

So, this leaves the cabin temp sensor. The SDL regulates the cabin temp with near perfection as compared to the temperature wheel. I'll bet it's within five degrees. So, I conclude that this sensor is working properly.

This leaves the conclusion that it is far more likely that the cabin temperature sensor is regulating the compressor, and, if faulty, it will dump the compressor if it believes the cabin is too cold.

While I have no data to make a conclusion with regard to this, maybe this anecdotal evidence will help you fellows determine the problem. I'd be real curious to see if the cabin temperature sensor cures this issue.

Of course, I am assuming that you have "ambient" air blowing when the temp wheel is off the stop. If it is truly "hot" air, meaning air above ambient, then all of the above won't help at all and you have a monovalve issue of some type.