I have a 2000 S-10 Blazer. 4.3L Automatic. It has the climate control heat and A/C. With the A/C on it blows cold for about 4 seconds, then heat for about 4 seconds. With the heat on it does the same. With all off you can still feel the heat coming out about every 4 seconds. I was told to disconnect the battery for fifteen minutes or so, but this didn't help. I was also told to listen for the air control doors to open and close. Hear nothing. The compresser clutch is engaged and the compresser seems to be working fine. When it does blow cold, it is very cold. I checked the freon with a guage, and it is fine.


Help Please................

 

Sounds like a faulty blend door actuator. It is located up on top of the HVAC housing accessible by dropping the glove box down. Small hands makes it easier to remove as does having a ratcheting low profile screw driver.

CLICK HERE for the HOW-TO

 

Does this vehicle have the electronic auto air? If so then it could be a defective gem module issue.

 

Thank you. I turned on the AC and waited until the cold was blowing then disconnected the actuator and had no more heat blowing. So that eliminates some of the issue. Now the issue is.......... What controls the actuator? How can I tell if the actuator its self is bad, or what controls it?

 

Just wondering if you found out what caused the actuator to open and close. Mine is doing the same thing.