Just replaced the heater\air conditioner blower motor in my 89 240dl. Frustrating job but it's done and everything seems to work O.K. EXCEPT the temperature thermostat (temp. controller or whatever it's called) for the heater and A\C. The temperature of the air blowing through the vents is constant so it seems a pretty obvious suspect. I can't say wheather or not the thermostat was good before I changed the blower motor because I bought the car with it not working. I need A\C here in arizona. heater doesn't matter. The fittings are 134A and upon attempting to charge it myself I noticed a little window (can't remember exactly where now, car is gone) in the a\c system that indicated (I think) that the system was full of freon. In addition to this, when I turn the Air cond. from OFF to ON, the air compressor starts running, so I'm pretty sure the system is charged. BUT not completely sure. Never in my lifetime have I seen an automobile air conditioning compressor run without freon in the system, and I can't see where it would be possible. Given this there must be freon it the system, the puzzling part is WHY the air compressor will not shut off (even for a second) intermittedly as they all should. As long as the Air conditioner Is turned to the ON position the compressor will run continuously. Regardless of the fact that the air being blown through the vents is warm or whatever other reason, IT RUNS NON-STOP. Can anyone tell why the a\c compressor won't shut off? If I still need to charge the goofy a\c system? And anything beyond the obvious I may need to know B4 changing the thermostat, assuming that's what it is? thank you very much.