For the past week, the temperature has been in the single digits overnight here. I deliver newspapers and my heater seems to blow lukewarm air and the engine temp never seems to get over 195* unless I sit and idle for 30 minutes or more. When the air temp gets up to around 20*, everything works normally. I did notice when I turn the blower speed down, the heater gets hotter. It must be most of the energy is used up warming the air up before it get into the cab. When it's above 32*, the heater will drive you out of the cab unless you turn it down. Am I missing something? The coolant was changed and the system flushed last July. The heater core was clear then.

 

Sounds like the thermostat isn't opening all the way. Thermostats are 80% usually the first problem with heaters not getting warm enough. Sounds like it opens up enough to feel warmer at higher temps outside but not enough for when its colder. My 04wj I6 will run u out of the cab when its 6degrees outside. I have people tell me all the time my jeeps heat is crazy hot. I just changed my thermostat in September because my radiator went out and why not just do both lol. My grand Cherokee has 131k miles on it and I swear this year my heat is better than last year.

 

I was thinking it's the thermo, but it seems to me it's opening too far too fast and not holding temp. This thing has had a rock solid needle at the 210 mark winter or summer and never getting more than one needle width either way from there. This is a sudden problem that just appeared since the temp outside got Brrr! I guess I'll change it as soon as I find a warm place to work.

 

May also be a blend door sticking closed.

 

I don't think so because the blower has lots of force and goes where I direct it.

 

heater core plugged??