Heat only works when driving

[Dravery1]

I have a 2004 Chevy Tahoe z71 with 5.3
I put a cold air intake on there and I was only getting hot air out of the driver side and ac out of the passenger and rear air when I had the AC on.

I looked up and saw it was probably the door acuator that needed to be replaced. I replaced it and it all started working again.


Well its getting colder now and I have tried to run the heat. The heat will not work on idle, only blows hot when I am driving. When Im idle it blows cold air.
The rear air also only blows cool air whether I am idle or driving. I took the Cold Air intake off and went back to stock box. Still not working correctly

I dont see any vaccuum lines, but what could I be missing.

Thanks for your help

 

[jblaze213]

Interesting because I'm having a similar issue. I have a 2006 Yukon Denali and now it's cold where I live and the hot air won't come on until I get on the freeway in the morning. I can warm the car up before leaving the house and it doesn't matter until I'm doing freeway speed.

Any thoughts? Not sure where to start looking.

 

[NJTahoe]

Ok I just got an 01 Tahoe last week and I had the same problem also. No heat.
I worked on it for about 4 hours this past weekend and I had two problems why I didn't have heat. The Blend Door Actuator was not working and the heater core was full of muddy Dexcool. I drained the coolant and then ran a hose through the system while the Tahoe was running and waited till it was coming out clean. Once it was coming out clean I put in a coolant system cleaner, available at any parts store. Then let that run through for a while with the heat blasting, though, it did take a little bit to actually get some heat going. Once that was done I drained it again and ran a hose through the Heater Core and so much gunked up crap came out. once that ran clean I ran the hose through the cooling system again with the truck running and the heat blasting until that came clear and let that drain. Put in about 2 1/2 bottles of fresh Dexcool and heat is hotter than ever. I still need to replace the Blend Door Actuator, but I'm waiting until the weekend.


Things to check
-Blend Dorr Actuator
-Coolant (level and if it's muddy)
-Heater Core

Good Luck!!

 

[stingray]

Ok I just got an 01 Tahoe last week and I had the same problem also. No heat.
I worked on it for about 4 hours this past weekend and I had two problems why I didn't have heat. The Blend Door Actuator was not working and the heater core was full of muddy Dexcool. I drained the coolant and then ran a hose through the system while the Tahoe was running and waited till it was coming out clean. Once it was coming out clean I put in a coolant system cleaner, available at any parts store. Then let that run through for a while with the heat blasting, though, it did take a little bit to actually get some heat going. Once that was done I drained it again and ran a hose through the Heater Core and so much gunked up crap came out. once that ran clean I ran the hose through the cooling system again with the truck running and the heat blasting until that came clear and let that drain. Put in about 2 1/2 bottles of fresh Dexcool and heat is hotter than ever. I still need to replace the Blend Door Actuator, but I'm waiting until the weekend.


Things to check
-Blend Dorr Actuator
-Coolant (level and if it's muddy)
-Heater Core

Good Luck!!

Thanks for the info.

 

[NJTahoe]

no problem

 

[0352Marine]

You should probably reset your ac/heater head unit. Just unplug the battery for 30 sec plug it back in and start the truck. Do NOT touch the controls on the head unit it is calibrating if you do you will mess it up and have to start over. Let it calibrate for about 4-5 minutes. Any time the battery is disconnected or the truck looses power you have have to let the head unit recalibrate. Alot of shady mechanics have tricked alot of people into buying stuff they don't need and charging them out the waazoo. hope this helps.