Having the same problem, first the heat and then the defrost. Now my low speed doesn't work. 2 and up are fine. anybody get an answer yet?

 

Mine's working now but it took voodo. I really gave that thing a good shot at home but wasn't able to get it. I mean I switched actuators around, took them apart and cleaned, even took two apart and made sure that the resistive range of the potentiometers were the same and that the sweep/zero span were set the same, tried a different control module, tried to clear codes, tried to recalibrate control module, and on and on. Finally broke down and took it to the dealer. They "cleaned" the connections on the actuator that didn't operate and it just started working for them. I still kindda wonder if they did the reflash mentioned in so many post but didn't tell me as I had been begging them to flash it for me. I just know that I had the actuator in question out of there at least 10 times and had cleaned on the connection points several of those times.

 

I have the same problem with my 04 silverado. When I am in manual mode the system has a problem with controling the temperature in the cabin. One moment it will be just right, then it will change to full hot. After a little while it will go to full cold. I notice that the temp will go hot even if the system is off. When in auto mode the temperature stays at what is suppose to be. If I am in manual mode and the system is blowing out hot air, I can switch to auto, and it will change the air coming out of the vents to cold to bring the cabin temp to the set temperature. I have trouble shot all of the components that I am able to work on. I have recalibrated the module many times. I don't have a problem with my blower motor because the fan speed changes appropriately. I don't think that I have a problem with my Temp sensors because when i'm in auto mode it controls the temp correctly. Do you think that it is best to just change the Control Module? If you could give me some advice I would appreciate it. thanks

 

I am having the same problem with my 99 silverado....air wont blow oout of the vents but it will blow out of the defrost.

 

I have a 2000 suburban lt with electronic climate control... no heat at all... i put in new blower, nothing, then a/c heater control module new 130.00 bucks, still no heat! the two wires leading to the a/c heater control module have 12-14 volts so there is power going to it, do i have to reprogram it? fuses all look good also no burnt wires or anything... power is still going to switch (green backround lighting still comes on around *****) any help people? this is my first time on here so i didnt know how to start a new post

 

ok need help reading so much actuator driving me nuts 2004 silver ado replace battery a/c blows cold air thru defrost vent .ok ac off look at actuator above gas peddle turn ignition key on i see actuator move up then all way down stays there now a friend has same truck 2004 i do same thing as mind turn e ignition on look up at actuator it does not rotate like mind only when start truck and move the directional floor vent straight vent also when it rotates down its vent for defrost