Where's the heat?

[mu2bdriver]

I experimented with blocking the grille this morning on my 50 mile highway drive home to see what it would do to engine temps and heat output. Normally, under similar conditions to this morning the factory gauge would sit between N and O. Blocking just about the entire grille moved the temp gauge as high as the M and then back and forth as I weaved through the hills. No noticeable change on cabin heat and this is with a full radiator and MC thermostat.

 

[BDCarrillo]

Heater core coolant blockage/corrosion?? Airflow blockage? Blend door inop? Vacuum lines boogered?

 

[3Kp]

After working Saturday I was able to spend some time with my truck.

After driving my son to basketball practice found out that I had no brake lights. I picked up a new stop switch and installed it still no dice. So I cut off the harness and installed wire connectors (plugs) now I have brake lights.

As for the heater I pulled the glove box out. Tested the temp controller which worked correctly. I was checking the fan speed switch which is fickle, I believe there is a resister switch somewhere on the truck. If I change that out I think all would be good?? Any idea of where the switch is?

The hoses did get pretty warm as did the air in the cab. But it was only in the 50's (didn't have to work as hard)