My '99 Silverado started out last year having difficulty switching from air conditioning to heating. For a while it seemed like if you had temperature control set on cold when you started the vehicle, that is what worked. If on hot when you started the vehicle, then you got heat. Once the vehicle was running, you could not switch back to the other until the vehicle had been turned off and cooled down.

Now the system is permanently stuck on air conditioning and it is starting to get cold in New England.

Has anyone had a similar problem? Can I fix it by replacing the dashboard control unit or could it be something else?

Thanks.

Volcano_joe

I have the same problem with my 99 also. I was wondering if you had found a fix for the problem yet? If so could you ledt me know what needs to be done.

Thanks jeff

I determined the problem with the heater. There is an electronic actuator on the bottom side of the heater duct (inside the cab). The actuator controls the flapper valve that switches the system from heat to cool and back. I replaced the actuator.

The actuator was expensive, around $60 at the dealer just for the part. You can find it on-line cheaper.

I replaced it myself. It is real easy to replace.

I'm having a similar problem with my 2001. If I leave the heater on for any length of time nothing but hot air will come out even if I turn it too cold or even off. I'm assuming the actuator you talked about is the same problem I'm having. How much did you have to take apart to put a new one in?

Sounds like the same problem. You just have to remove the kick shield on the passenger side (4-5 screws).

Then pull the actuator off (2 screws) and an electrical disconnect. The actuator is a small black plastic case that is about the size of the palm of your hand.

It is on the bottom side of the blower unit you exposed when you took the kick shield off.

Joe

Joe
Thanks for your help. I just removed the actuator and manually turned the post in the blower unit and sure enough I got hot air again. Now I just need to go buy a new actuator and install it, might as well buy a couple of new tailgate cables while I am at it also.

By the way, I didn't have a kick shield over the actuator.

Jeff

dja,

Your welcome. Best of luck to you.

Volcano_Joe