Heat is always on and it isn't the blend door

[ckal944]

I have a 2000 5.0 limited with the automatic temp control. The heater only blows hot air. I replaced the blend door actuator and the blend door works smoothly. When I changed the actuator, I tested them both when they were out. I noticed that when changing the temperature on the heater control that the actuator didn't move with the old or new actuator. I replaced it anyway knowing that this probably wasn't my problem but it was a pain to get out and back in so I put the new part in anyway. I read one forum that talked about the GEM unit as a possible fix but didn't see any other forums that addressed anything other than the blend door or blend door actuator. Everything else works so I am thinking that the GEM is not the problem. Also, everything else heat/AC related works as well such as changing from panel to floor, fan hi to low, etc. I don't really want to just throw parts at it. I have to assume that the new part is good and when it didn't work I knew it was probably something up the line before it so here I am again. Please help. Any suggestions will be welcome.

 

[R1dd1cK]

Well maybe you have a bad climate control unit. I just looked at the wiring diagram and the climate control is not hooked to the GEM. All 5 wires for the blend door actuator go from the back fo the climate control unit straight to the blend door actuator. I guess it may also be a broken wire.