2003 Silvy No Heat Unitl Driving

[mshell56118]

I have a 2003 silverado ext cab 5.3 that I typically start and allow to warm up usually after about 5 minutes the engine is warm & the heater is blowing hot air. Here recently the engine temp gauge shows warm but the blower only blows cold air. If i drive the truck down the roads a few mile it starts blowing hot air. Any ideas to help fix the problem would be appreciated

[bobcat5544]

1st thing you will need to do is let the truck sit and warm up, After it is fully warmed up locate the heater core hoses under the hood on the passenger side of the firewall under the hood. Feel both hoses one hose will be warmer than the other. The hose that is the warmest see if it feels just as warm as the top radiator hose. Now rev the engine or drive it for a few min and check the hoses again does the hose feel warmer or the same..

 

Let me know what you find out and we will go from there.