1998 Chevy Blazer ac/heater problems

Hello, I am having a problem with my ac/heater in my blazer. I unplugged the battery and after plugging it back in I was driving and my car started switching from hot to cold over and over back and forth. I can switch it to defrost and floor and all the different vents but then after a couple more trips it now stays on heat. I think either the actuator door has stopped working or the control on the inside is broken. It has the computer controlled climate thermostat in it, not the regular it has a auto setting etc.. What should I do first? Could something shorted out when plugged it back up. It worked fine before I unplugged battery..

Thanks for any help...

I just wanted to add there is nothing wrong with the ac compressor etc its fine you can here it kick on and its been checked it actually kicks on still when I put the ac on from the inside. When it was switching from hot to cold it wasnt just like ac then a little warmer you can hear the difference of air flow and it was like full blown hot as it gets opened up all the way! Even with the switch set to off while driving you can still feel a little heat coming out also..

how many miles on the truck?what engine(V6?...vinW?...)?other than the battery any other work or parts, sensors changed in the past? has the fuild been flushed?

It has a little over 100k. Been serviced at dealer all its life. Ac delco replacement parts. What does any of that have to do with a faulty ac switch or sensor or actuator door malfunction? It has V6 4.3 CPI All fluids look great.

I had a similar problem a few years back. It was the actuator located in the glovebox that went bad. It's a do it yourself thing but kind of tight due to the space in the glovebox. Hope this helps! :smile:

Hello, I am having a problem with my ac/heater in my blazer. I unplugged the battery and after plugging it back in I was driving and my car started switching from hot to cold over and over back and forth. I can switch it to defrost and floor and all the different vents but then after a couple more trips it now stays on heat. I think either the actuator door has stopped working or the control on the inside is broken. It has the computer controlled climate thermostat in it, not the regular it has a auto setting etc.. What should I do first? Could something shorted out when plugged it back up. It worked fine before I unplugged battery..

Thanks for any help...

I just wanted to add there is nothing wrong with the ac compressor etc its fine you can here it kick on and its been checked it actually kicks on still when I put the ac on from the inside. When it was switching from hot to cold it wasnt just like ac then a little warmer you can hear the difference of air flow and it was like full blown hot as it gets opened up all the way! Even with the switch set to off while driving you can still feel a little heat coming out also..

If Automatic AC air controls?

Try the relearn procedure.

Key off remove RDO/Batt fuse a few minutes.
Be sure to check fuse.

Install it back in and turn key on.
You should hear the actuator cycle hot to cold or cold to hot and then start working.
Good Luck and.
Let us know how that goes.

Awesome MT-2500 - This procedure worked for me! Thanks!!!

If Automatic AC air controls?

Try the relearn procedure.

Key off remove RDO/Batt fuse a few minutes.
Be sure to check fuse.

Install it back in and turn key on.
You should hear the actuator cycle hot to cold or cold to hot and then start working.
Good Luck and.
Let us know how that goes.

Awesome MT-2500 - This procedure worked for me! Thanks!!!

You are welcome and thank for letting us know.

Well... I spoke to soon. It worked for about 5 minutes and started blowing hot air again. I tried the relearn fix again and it didn't work this time. I don't hear the compressor kicking in now either. Oh Well...

You are welcome and thank for letting us know.

Well... I spoke to soon. It worked for about 5 minutes and started blowing hot air again. I tried the relearn fix again and it didn't work this time. I don't hear the compressor kicking in now either. Oh Well...

Automatic or reg AC controls.

Does ac have proper charge?

My 98 Blazer with climate control had a similar problem. The blend door was stuck on cold and I could not get heat. I tried the relearn procedure, pulled the fuse waited, 10 minutes and put it back. I could hear something moving under the dash but still no heat. I tried the relearn again and sucess!! A week latter the heat is still working. Thanks very much MT!!!