NittanyXJ

So my 1999 XJ heater is pretty lack luster in the HOT department. I knew it was sub par prior to winter so this past September I went and flushed the radiator, water jacket, and heater core. and replaced with 50/50 prestone coolant. There was some improvement after the flush, but it still wasn't super hot. I have been reading the recent increase of heater problems and have been trying things that were suggested, both heater hoses are hot when the jeep is up to temp. The jeep during the winter runs around 185-190 and during the summer runs 210-215. The thermostat opens and closes during operation temperatures, I can tell this by watching the fluid level at the radiator cap drop and then rise again. the blower motor runs well on all settings, and speed levels. The actuator motor for the blend door spins in both directions when i change the heat level. Every once in a while i get little bits of black plastic blowing out of my vents. Is there anything else i can try? Is there a way to check the blend doors visually besides watching the motor spin?

67 GMC

I've got an '87 so not sure if mine is similar to yours. I had a lot of cold air being brought into the Jeep through the plastic housing inside by the passenger side. We've been having the extreme cold up here and I think something contracted and shifted. I thought I had no heat but I could feel warmth at the defrost vents but cold air at my feet. I had to wrestle the housing back together and it's been good. Also, the door that opens when you slide the selector wasn't moving all the way so I loosened that up.

Try putting your heater in "recirc" mode and see if that helps. Then it's not bringing in any outside air.

I feel your pain...

slowjunk

i have a '92 have pretty good heat coming out the vent, but below my feet it's always cold and don't feel any hot air blowing even when set on HI. which position the slider should be on to have heat blow on my feet?

NittanyXJ

The heating system for 96 and down is all different then 97 and up

Roler

Mate, really? You can work that out, I hope...
If anything, you might want to check your vent mode selector for functioning

slowjunk

i tried all the selectors but not getting any heat coming out below. im thinking of replacing the heater core.

Roler

You got heat, so why replace the heater core?!
You haven't got (much) heat coming from the lower vents thats all

slowjunk

good point spring is only 2 freezing months away lol.

NittanyXJ

Anyone have any other ideas to try?

jerrytrim

Could it possibly be your temperature **** that is faulty? If the electrical connections inside there are dirty it could be causing it to think you want a 'cooler' temperature than you think you selected. You could try pulling off the paneling and blowing some compressed air into the temperature *****.

cpttuna

Do you have a 195 thermostat?

77olds

Check your coolant, make sure it's full and there's no air pockets in the system.

Let your Jeep run and get to operating temperature, then touch the heater hoses in the engine bay. If one is warmer than the other, you either have an air pocket in the system (possibly due to a bad head gasket, leaky water pump, or other system leak) or a blockage in the heater core.

Read my thread for more advice.

https://www.cherokeeforum.com/f2/lit...6/#post2757959

CCKen

There's only one Blend-Air Door.

You can check the following:

Remove the Blend-Air Door motor, bracket, and shaft and inspect the Intermediate Drive Shaft and the Blend-Air Door pivot shaft. See images.

Just because you see the Intermediate Drive Shaft turning doesn't mean that it is turning the Blend-Air Door pivot shaft.

Inspect the Drive Shaft and the door Pivot Shaft coupling for being wallowed out. If there is damage to either, attempt to turn the Blend-Air Door pivot shaft with your fingers. If it won't turn freely, try using pliers to move it. If the door is jambed or extremely stiff to turn, the door needs to be replaced.

If the door turns freely and only the Intermediate Drive Shaft is damaged, it can be replaced.

If there is no damage to the Intermediate Drive Shaft or the Blend-Air Door pivot shaft, and the door turns freely, you have problems elsewhere.

Reassemble components.

The Blend-Air Door only turns 90 degrees full travel. Viewing the bottom of the actuator, Full Clockwise is COLD (Blue), Full Counter Clockwise is HOT (Red).

When you are going to install an actuator assembly, plug it in to the connector first before attaching it to the Blend-Air Door shaft. Operate the actuator full travel hot then cold, Stopping at Cold (blue), turn the Blend-Air Door shaft fully Clockwise, then install the actuator assembly. Ops check it for full travel Hot and Cold. You should see the Intermediate Drive Shaft turn in the in the appropriate directions.

NittanyXJ

Thank you guys for the info, I am planning on having a local radiator shop do a better flush than what i did in the driveway,if that doesn't get it I'll try taking apart that blend door motor. hopefully this will solve it if not you will hear back!!