I just picked up my second Blazer, it, s a 99 LT and there is a problem with the heater, it only blows hot Air and does not respons to the temperature I choose. Also the AC when activated switches off in seconds.
Any thoughts?

 

The problem with the temperature control sounds like the problem I recently had. There is an electronic motor controlled component called a "blend door actuator" that is known to break on these. People have worked out how to fix them when the problem is with a gear slipping in them. I chose to buy a NOS one off of eBay. Note that there are two types; one for the Auto-HVAC (temperature select) HVAC systems and one for the manual ones.

Access to them so that you can remove and install it can be gained by opening up the glove compartment and releasing the catch that allows the door to swing down vertically. Small hands and 1/4" socket set are necessary.

As for the AC, it might or might not be related to the blend door actuator. Is there enough refrigerant in the system? I'm pretty sure there are interlocks on the AC system that might cause it to turn itself off.

I would suggest you first check out the blend door actuator and try to diagnose if that is the/a problem.

Good Luck,

Christine

 

Thanks Christine!
Would you please post a link to the Nos part that solved your problem.


QUOTE=christine_208;682192]The problem with the temperature control sounds like the problem I recently had. There is an electronic motor controlled component called a "blend door actuator" that is known to break on these. People have worked out how to fix them when the problem is with a gear slipping in them. I chose to buy a NOS one off of eBay. Note that there are two types; one for the Auto-HVAC (temperature select) HVAC systems and one for the manual ones.

Access to them so that you can remove and install it can be gained by opening up the glove compartment and releasing the catch that allows the door to swing down vertically. Small hands and 1/4" socket set are necessary.

As for the AC, it might or might not be related to the blend door actuator. Is there enough refrigerant in the system? I'm pretty sure there are interlocks on the AC system that might cause it to turn itself off.

I would suggest you first check out the blend door actuator and try to diagnose if that is the/a problem.

Good Luck,

Christine[/QUOTE]

 

Go to eBay and search "A/C Actuator Air Door Vent 2003-14 Escalade Avalanche Corvette Silverado Sierra" to find the one I purchased. But there are very many available. Just make sure you find the right part number.

This one is for the Auto-HVAC systems. A good way to check part numbers is to go to a GM parts distributor or Rockauto and find the original part number then look for it elsewhere like on eBay.

A way to diagnose if you need an actuator is to gain access to it by opening the glove box all the way and then put your hand on the actuator and feel it try to move when you adjust the temperature. If you feel it move but with no change to the actual heat output, then it is the actuator that is likely at fault. However, if you can't feel it move then there might be a problem elsewhere in the circuitry.

Good Luck,

Christine

 

Update.
I looked into the blend door and I was lucky, it was the failing part alright but I only needed to calibrate them by pulling the fuse, start and so on.
Worked perfectly and it now works as it should.

Thanks guys!

 

Don't you love easy fixes like that? Definitely one for the Win category.