My heater is not properly warming up and I have no clue what could be the problem with it. I drive 15 miles every day and this morning it was 18 degrees Fahrenheit and by the time I had got to school my truck had still not warmed up, like not hot anyway, warmed up some in there but not like it should. I had it on the third setting blowing out the vents, all the vents are open, and it was definitely on heat. Any ideas??

 

Look at the first several threads on the top of this forum. This issue has been coming up a lot, must be winter. If your truck is not reaching normal operating temperature, after about 5 minutes, it's probably your thermostat. There are other ideas in those threads if that's not your issue.

 

Could be the blend door issue, or a thermostat. Are the hoses going to the heater core close to equal temp?