To program/calibrate the actuator. Is this something we can do ourselves or do I have to take it to a shop?

 

Have a read down through the thread linked to below:
Heating Issues!???

Found by putting "actuator+calibration" into the search box. Who knew!

 

Okay guys, I'm having a similar issue. I have a 98 LT 4X4 Blazer with the Automatic Climate Control Unit. I was having battery issues during the winter. Cleaned all the corrosion off. Soon afterward I lost all heat, then not long afterward I got back the heat but lost all cooling. Even on the lowest temp setting I get full heat. I can't even get cool morning air from outside through the vents. I am able to cycle between defrost, dash, and floor vents okay. I can control the speed of the blower okay, but still get heat coming out even when in the off position. I replaced the Automatic Climate Unit, and pulled the RDO fuses to reset. No luck. I dropped the glove compartment, and when I cycle through the dials I can see a silver arm move in the upper left corner. Also I can see a large black door move up and down on the lower right side. I keep reading about the gears in the "blend door actuator" breaking, but yet I can see things moving inside the glove box. Any ideas?? I'm at a complete loss and with warm weather coming I'm burning up!! Thanks for any help!!

 

CincyFireman, that is the exact problem I am having. I am going to try to get the interior temperature sensor this week and replace. I will let you know how that goes. I have been told faulty accuator also could be problem but that costs $130 at KOI and interior temperature sensor is much cheaper so i'm starting there. Good luck with yours and update if you find solution.

 

Try to fix the blend door actuator gear before running out and buying a new unit. I have a 99 with automatic climate controls. I put my gear back together with a good epoxy. Put a hose clamp around the gear to hold it together. There is a large groove in the top of the gear that I completely filled with epoxy, this will hold the gear together and hold the gear to the metal stem. You can't fill the groove on the bottom side because part of the case slides in that groove, but you can put a thin coat in that sopt. I did this 3 months ago and so far so good. It's probably stronger than original.

 

Ok lastest update on blend door problem. Got 2 sensors from junk yard, one from 99 blazer and one from 2000 blazer. Still no change, still living with the hot air. Any ideas anyone? The compressor is not even kicking in now. Was every 5 seconds now nothing. I have 3 sensors now and there is no difference with either one installed.

 

Been researching this blend door thing since this January. Made a trip to Texas from NC. Was cold outside snow from east coast to Miss. Anyway, no funds or good time to drop dash. 98 Blazer. Went cheapest way...By-passed the heater core. Looped hose now got cold, YEA. I did the blend door inspection it functions. The door just is not making a good closed fit. I knew the A/C works, had condensation under vehicle. Now to make ready for the dash drop or sell to my brother and get something else. Trying to get another 30,000 out of her.

 

Is a 98 dash the same as a 99? On my 99 you can get at the actuator by taking the glove box out. It was a tight fit, but I got mine out in about ten minutes.