heater blows cold on 1997 Chevrolet Tahoe

i forgot i also change the heater control valve it worked great for a few days then started blowing cold again

by in Oklahoma City, OK on November 26, 2012
1 answer
ANSWER by , November 26, 2012
check for full of radiator fluid (low fluid = no heat), if full may need new thermostat - you can check the old one by placing in freezer till cold and run under hot water and watch to see if it opens