Luke warm heat at best........

[captainshane]

I have a 2001 Tahoe with 170,000 miles. I have notice (for sure on the way home today) that the heat is luke warm at best. Temp gauge is at the normal temp. The t-stat is original. Heater core hoses are the same temp (warm) but the upper radiator hose is hot and the lower hose is cold. This Tahoe does not have a radiator cap except the cap on the overflow tank (15 psi). Overflow tank has the proper level of antifreeze. So could it be a bad t-stat or core, or even something else.

ps. Temp control works because you can see the damper open and close properly.

[Jeremy airjer W]

If the gauge is in the normal spot than the t-stat is working.

How does the coolant look? Like Mud?

I would start with backflushing the heater core. It may take several tries. If it starts to blow hot then definitely flush the entire cooling system

[BobT]

Sounds like the fluid is not flowing through your heater core if those hoses are only warm. I'd agree with airjer

[snowfighter]

Don't know about newer cars but some of the pickups I had in the 80's& 90's the temp lever that controled heat temp the cable that ran from it to the control lever on the fire wall(heater core) would slip so it was not opening the valve full way. One just has to readjusts the fitting on the end of the cable.

[RebelSS]

The lower hose is cold?! You're not circulating your coolant..look for a bad heater control valve, or your water pump/impellar blades just went south....

[captainshane]

Well the only thing I came up with is the cap on the overflow tank was bad. Cap is 15 psi. Replaced cap. Heater works great. Core hoses are hot. Fluid levels are good. Lower hose is cool even after being on the hwy for an hour.

"its all good"

thanks

[Surface Tension]

Out of all the hoses the lower radiator hose should be the coolest. That hose is this supply to the block after the fluid has been cooled in the radiator.

[captainshane]

You are right Surface T. The lower hose should be cooler and for sure on a cold day. Not sure why I didn't have heat that day. Had heat on the way to the cities, didn't have heat on the way home. Was on the highway for 3 hrs round trip yesterday and had the fan on 1 and 2 out of 5 (high) and we were plenty warm. We will see what the future holds I guess.

Thanks for all the info,

Shane

[MNice]

Check your HVAC air filter under the passenger side.

[captainshane]

MNice, I also changed the cabin air filter. Itwas dirty. So it could of been a combo of dirty filter and a bad cap.