2000 Chevy Silverado heat

Hey Fullauto, I am in the same boat at 240,000 mi. I have some heat however something is not right. I am wondering if you replaced your thermostat and that fixed it? I plan on putting one in this weekend. I don't think I have a door problem because it does change from luke warm to cold if I turn the switch. I am also thinking of flushing out the heater core with a garden hose to see if that helps. Any input from your situation would be helpful. One thing I don't understand is why if my engine is at 190 degrees wouldn't my heater core be the same temp as well?

Tvzz
1. Check heater core hose and make sure both are hot when all is running and warmed up.

2. If not heater core is plugged. Remove hose and back flush with garden hose or fill hose with water and use air pressure make sure you don't use to high of air pressure or it will cause damage.

This was my problem. Hope this helps all.

As suspected only one hot hose to the heater core. I did buy a thermostat just because It was easy to change anyway. Took it all apart and was flushing the heater core and broke the stupid plastic fitting near the firewall. I ended up cutting the fitting off the metal tube and putting the hose directly on the tube and clamped it with no problems, whew. I found it best to electrical tape the garden hose to the heater core hose and turn it on slowly, I flushed it for awhile, turned up the pressure and saw the flow easily increased out of the other end. Put it all back together and now the heat is great. Figured I would post for anyone else researching. Fullauto I appreciate your input. Happy Thanksgiving.