72gs455

So the 99 Cherokee had poor heat. It seemed to blow warmer air while you were driving/accelerating. So I figured it was the stat, I put in a new 195 and now it seems worse. Almost no heat what so ever, coolant is clean. Radiator is a year old, flushed the core and it is clear. What am I missing?
Thanks for any help...

tjwalker

1. If you have similar heat (low to none) with both your old and new thermostat, unfortunately your heater core is still in play, even though you've flushed it. Feel both the hoses going into and out of the heater core. Are they both HOT?

2. Cab heat is a product of engine heat. What does the coolant temp gauge read on your dash? Is it consistent? Verify your coolant temperature with an infrared point and shoot thermometer pointed directly at your thermostat housing. Should be in the 190-200 range.

3. Also in play is your HVAC blend door controls that bring heat into the cab. Verify that these are working properly.

Good luck and keep us updated!

Firehawk068

What kind of Thermostat did you install?
It wasn't a "Failsafe" was it? They are prone to locking open even at normal operating temp. When it does, you will get no heat................

Make sure your coolant is topped-off...........Low coolant level can result in low/no heat from the heater..........

Also, I'm not sure if your '99 has a "Heater Control Valve"......my '96 does.
It controls the flow of coolant to your heater core by means of a little vacuum hose from your heater controls inside the cab...........
If the vacuum hose is broken anywhere in the system, it may be stuck in the (bypass) position, and you'll get no heat..........

djb383

The heater control valve was eliminated by the Factory on '97 up.

SteveMongr

Post #2
x2

(that was easy)

72gs455

Rookie mistake... Radiator cap was loose, kid took off before I was finished I guess. Anyhow I flushed the core again refilled and put the cap on fully and now it seems good.
Sorry to put you through the process...

IJM

Rookie is buying the first round for us. Glad to hear it worked out.

hicj7

I had a similar problem in my 99 XJ and drove it for some time with out much heat. Full blast heat gave about 80 degree vent temps. What I had was a broken blend door.It was broken at the bottom where it connects to the blend door motor. Dorman makes a problem solver replacement door that replaces the bottom part of the plastic door with metal. When I did my replacement, I took the whole dash off and replaced the heater core AND the blend door. I even think there is a very well read thread on here about replacing the heater core here. BUT, if you were just going to replace the door, Dorman includes instructions on how to do that WITHOUT removing the whole dash. Click and check it out!

http://www.oreillyauto.com/site/c/de...4109&ppt=C0328

hicj7

Ugh! Should have read more thoroughly...