I have a 03 Ram with 225,000 miles. The problem I am having is the heat will not blow hot air. It will blow slightly warm air but not hot. I changed the thermostat and that did not help. The temp gauge is showing normal operating temps. Any ideas on what could be causing the problem?

Thanks in advance

 

1. Cloggged heater core (225K miles this is a high probability)

2. Blend doors in dash

 

It was a clogged heater core.

Thanks for the help!

 

What he said.