out of curiosity I actually took a mercury thermometer and measured the temp of the heat exiting my vents. vehicle was at full operating temp idling in my driveway, needle was dead on one mark left of 210 on the dash. ambient air temp was ~10*. it was on full hot, the face vent setting, and the lowest fan speed.

my thermometer only read to 120*. I stuck it in the vent and within 15 seconds it was at 120 and still climbing rapidly. wasn't sure if what happens in cartoons is true or not so I removed it.

wanted to share my findings and curious if anyone else has done this. I felt like the heater worked very well but had no basis of how well.

 

FSM says minimum 144F at floor vent 60F ambient.