2004 Gmc Sierra 1500 5.3l

[malibu327]

After my truck is warmed up according to the temperature gauge, the heater will not blow heat unless you are accelerating. example, if i am stopped at a red light, it will go from blowing heat to cool air, once i take off, it will start blowing heat again. Now back in the summer, the air conditioner did this a few times. While i would be sitting still, it wouldnt be blowing good cool air, but once i took off driving down the road, it would. I have no idea on how alot of this stuff works, but i'd like to give it a try. I dont have the money to take it to a dealer so i'm kinda messed up there. If anyone knows any suggestions, i'd really appreciate it.

 

Thanks.

 

EDIT: To go ahead and answer some questions that may be asked, the coolant level is fine and the truck temperature gauge is at or around 190. I searched heater problems and these two questions seemed to come up quite a bit

[malibu327]

I know I'm in Arkansas, but it does get fairly cold here. If anyone knows anything, or if you need more information, please post a reply.

[DofD]

It sounds like you may have a clogged up heater core such that the coolant can't circulate through it properly.

[kimmy gibler]

My 04 hoe is doing the exact same thing! I would like to know the issue as well so I can fix it.

[malibu327]

So what Ineed to do is a complete system flush?

 

 

It sounds like you may have a clogged up heater core such that the coolant can't circulate through it properly.

[ALKEMIST187]

i had the same problem on my 00 suburban, yup, just the flush, & you should be perfectly fine...

[malibu327]

Well I just got done flushing it and letting the truck warm up in the driveway and it still isnt blowing any heat. Unless someone else knows of anything else I'm just stuck with it. Thanks for all that tried to help.

[2000DV4.8]

Well I just got done flushing it and letting the truck warm up in the driveway and it still isnt blowing any heat. Unless someone else knows of anything else I'm just stuck with it. Thanks for all that tried to help.

 

Try purging the system to remove any air? I've had my own troubles with my heat, and I've tried just about everything. Flushed the heater core with a garden hose, purged the air out of the system about 3 times, which worked for a day or so, but somehow the air is getting back into the system. I also had the dash apart to check all the actuators (they were good).

 

I'm at my wit's end.