2000 silverado doesn't blow very hot air

[trapperman83]

Let me start with the things I've done and tried, it has a new water pump new cab filters and system was flushed and I used 50/50 green antifreeze, I thought it was the accuator so I pulled it off and manually closed the door and same thing, it will get pretty warm idleing but when u start driving down the road it gradually gets cooler, any ideas? The temp gauge goes up then u can tell when stat opens up and it goes to about half way on the gauge. Not sure if heater core is plugge or what. Thanks.

[MMC]

Did you replace the T-Stat already? That's always the best place to start but you did not list that.

[trapperman83]

It was replaced when the pump was about 10 months ago but this started after that used to work gret even after pump was replaced according to the temp gauge the t stat is working gonna check my core hoses to make sure that valve is working .

[Desi]

Had an '04 that had the cooling system flushed and heat tapered off afterwards. Apparently a flush can dislodge crud and it can wind up in the core. My experience anyhow.

[Bad Bowtie2]

I agree. Remove the two heater core hoses and lightly flush it out BOTH directions. Use only tap water hose pressure, don't force it in any stronger.

[trapperman83]

I will get a new stat and flush the heater core I've replced the rad cap and it made no difference so we'll see. Thx

[trapperman83]

Ok so got an update.

 

I replaced the stat cuz I noticed one of the lines to the heater core was cool not hot it was the line that tee's into the overflow resivor line. System burped added about a quart to top it off then it was blowing hot again, I did blow out the heater core but a hose was unavailable cuz it was 10 below, so I used air not sure if it did any good, but today it went back to blowing Luke warm air again, but I noticed one thing today when u switch temp control from hot to cold it blows really hard out the vents but when u go back to the hot side it's like u turned the fan down about 2 speeds now I'm really wandering what the heck is going on lol. Any help would be greatly appreciated. Thanks.

[Colossus]

I still strongly feel that the whole system needs a good flush with the right tools and system. And replace the thermostat once again once that is all done. It's amazing how much junk can accumilate in the radiator, ports, and cores in these vehicles. The only system I know of that does an outstanding job has been the Gates Powerclean flush tool. Find a good shop that ownes one of these things. They are way too expensive to justify getting one for yourself but I am a firm believer in it after having seen a few vehicles, new and old, flushed out with this device and the results afterwords, vs a traditional flush.

 

Good luck!

http://www.gates.com/products/automotive/tools-and-sales-aids/professional-tools/power-clean-flush-tool

[trapperman83]

Your probably right but the only thing that could be gummed up is the heater core. The Radiator Water Pump and test at are all brand new.

 

Why does the fan speed drop from cold to hot? I don't recall it being like this when I bought the pickup in April

[trapperman83]

I will try to find a shop that can give it a good flush

[Bad Bowtie2]

Sound slike 2 different problems to me.

 

I would check out the wiring pigtail going to your blower motor resistor. See if it looks like the wires are getting to hot & starting to burn up....

[BLACK DEATH]

Any updates on this?

Does the heater blow hot now after the flush?

[Knotsure]

What about the havc control itself? I think my 06 sierra's hvac control unit is not working properly sometimes. It doesn't blow to the designated area I select all the time but I haven't really messed to much with it, I still have good ac and heat. Just throwing that out there.... Good luck