No Heat and winter is coming!

[Aero32]

Ok, So before it started to get really cold my heater was blowing air that was hot enough to cook with. Now it decided to only blow slightly warm air. What is the problem? Heater Core clogged possibly?

[rivalarrival]

Most likely, a thermostat that is stuck open, which won't allow your engine to reach operating temperature, and you'll get no heat. Does your temperature gauge reach 190-210? If not, test/replace the thermostat.

[tellicojeeper]

do the hoses going to and from the fire wall get hot. if one is and the other isnt, prob. clogged. but id start with the t,stat.

[Aero32]

Originally Posted by rivalarrival

Most likely, a thermostat that is stuck open, which won't allow your engine to reach operating temperature, and you'll get no heat. Does your temperature gauge reach 190-210? If not, test/replace the thermostat.

Yeah, The temp gauge reaches around 180-190..

Originally Posted by tellicojeeper

do the hoses going to and from the fire wall get hot. if one is and the other isnt, prob. clogged. but id start with the t,stat.

I'll have to check the hoses tomorrow, should I check them with the heater on? off? doesn't really matter?

[Boodyrider]

check with heater on.

Also check coolant level.

[retroflow]

I say it could well be your Thermostat. Go ahead and check the Heater Hoses when the engine is hot just to rule it out. But you said your TJ reaches around 180-190F, which sounds suspect. I could see between 195-200F on a long drive, but not 180-190F. My TJ is a '97 and hasn't run extended much under 210F in years, even with fresh coolant and a new Radiator Cap.

If it's your Thermostat, replacing it is a messy but fairly easy and straightforward job. I used to swap the Thermostat out of my 1970 Ford Maverick twice a year - Either the 160F or 180F for the hot Southwestern Summers, and the OEM Spec 190F for Winter. When I moved to the Upper Midwest in February '02 for a bit, I hadn't swapped out the Summer Thermostat yet. The difference between 10-20 Degrees with Thermostats made a huge difference...it was a miserably cold driving experience. Just warm enough to defrost the windshield but I had to wear a hat, gloves and keep my jacket zipped until April/May.

[kloppk]

Another possibility is the blend door may not be moving fully to the hot positon. If it's sticking, or not moving you'll get poor heat.

[Aero32]

Well both hoses are hot...really hot. So I'm going to say either thermostat or the blend door isn't working properly

[tellicojeeper]

if the hose are hot then the core is hot. need to check the blend door. it will keep from the heat entering the blower motor

[erickpl]

Had the exact same problem. Does your TJ take forever to get up to operating temps?

If so then your likely culprit is your water pump -$32.00 from auto parts store. Do your tstat and do a good flush and you'll be fine, but be sure to do a reverse flush to get the gunk out of your heater core.

My hoses felt like it was a tstat too but after swapping it didn't make a difference. The new pump did. B sure to see if it is a reverse flow - you can tell if there is an R stamped on the impeller.