Heater problems and it's freaking cold!

[sirhcdeer]

Ok, so my 2000 GMC Yukon is blowing cold air at idle RPMS's. The coolant was changed out about 10 months ago, so it's unlikely that there's a problem with that (level is great).

After startup, I've let the truck run for upwards of 15-20 minutes and get only cold air. BUT, if I rev the RPM's to around 2000, the heat starts to increase fairly rapidly, however it starts to reduce in temperature when I let the RPM's go back to idle.

I HOPE to GOD it's not the heater core, as that looks like a brutal replacement project.

Could it be clogged?

Any thoughts people?

Thanks!

 

[Goodinblack]

Check vac lines?

Increasing idle speed does not make the blower go faster...... not really.

If your heater core went out you would definitely know it.

The sweet smell of antifreeze burning is hard to miss.

I have pulled many a dash.......

Town Cars..... Aerostar...... 79 Firebird........

 

[ccapehartusarmyINF.(ret)]

ive had several vehicles were the heater core stopped working there usually a valve that opens in the engine bay that lets coolant into the heater core or just bypasses it if the heters off but here in arizona you never need a heater so its never a high priority heater cores are always extremely time consuming to change out
avoid at alll costs most reqquire like the whole dash to come out there rediculous

 

[YukonBill]

If it any help I just went thought his on my 06 Grand Prix. The heater core was plugged up. I removed both hoses to the core and attached the garden hose,turned it on low and flushed the core and now it works perfectly. With the engine at operating temp turn the heater on and feel the hoses to see if there is hot water on both sides. In the case of the Grand Prix hot water constantly flows though the core So it was not a valve issue. This Grand Prix only has 80,000 miles on it and i believe it was the DexCool that caused the problem.