Need help with heater issues

[51093]

Hi im having issues with my moms 2004 tahoe base model, the heater does not blow hot air when its parked or stopped only when driving. We recently replaced the thermostat, could that have linked to this problem? thank you for any helpful information.

 

[justimagination]

:welcome:
I would suggest checking both heater hose's with the engine @ operating temperature. Both hose's should be HOT. The thermostat you replaced, by any chance did you notice whether it was stuck OPEN when you took it out ? Just a common problem causing poor heater operation. JMHO Good luck
david g.