2000 Sport low/no heat In Michigan!!!

Hi All!
I have a 2000 sport, 4.0L/Auto that I LOVE! but I'm freezing my buns off in all winter.

I bought her last November, and was a little C-O-L-D last winter. I read/lurked here, and thought that I had a blocked heater core.
Well Come spring time/warmer weather, It was getting a little warmer then I would have liked...so...I gathered up the stuff this past summer, and replaced the Radiator, Water pump, & thermostat . I flushed out the block, and the heater core (I had a nice flow through the heater hoses both ways)...and thought I was golden.

Now I am getting the same symptoms (Little/no real heat inside). I thought it might be a loose heater cable from the control on the dash, or a broken control...so I got on Ebay and bought (what I thought was) the correct heater/AC control.....Pulled it all apart tonight when I got home from work, and Sha-Zam! it's not a cable controlled system at all..:doh:

The Hayes manual has been less than useless for this...

Luckily I am a former mechanic, and current Electronics guy (25+years) so I'm not >Totally< clueless :lecture:!!

I took the control apart, and tested the potentiometer that controls the "Heat" setting...it's fine....

But I need a diagram of the heater control system.. like where the (??missing??) heat control valve/motor/door, or whatever it is that controls the cool/heat, is located on this thing so that I don't have to freeze again this winter.

Any/All help would be GREATLY! appreciated!!!

Thank You!
Tall Shadow :dunce:

where in michigan? done any wheeling recently

2000 does not have a heater control valve. It could be a stuck thermostat. If it isn't the thermostat, you may have blockage in the heater core that didn't flush out.

Jess said:

2000 does not have a heater control valve. It could be a stuck thermostat. If it isn't the thermostat, you may have blockage in the heater core that didn't flush out.

Click to expand...

It does however have a blend door in the box behind the dash. It should be actuated be a little electric motor. I'm not exactly sure where it is but if you can't see it behind the covers under the dash, it might be behind the glove box. They're usually semi-accessable.

bdavid said:

where in michigan? done any wheeling recently

Click to expand...

I'm in the Metro Detroit area (Royal Oak specifically). But I do have a place (Cabin) in-between Gladwin & West Branch.

Where are you?

Tall Shadow

Jess said:

2000 does not have a heater control valve. It could be a stuck thermostat. If it isn't the thermostat, you may have blockage in the heater core that didn't flush out.

Click to expand...

New Thermostat & it is working (Heater hose(s) getting hot), and I flushed the heater core (both ways) when the rest of the work was done.

Tall Shadow

BudgetXJ said:

It does however have a blend door in the box behind the dash. It should be actuated be a little electric motor. I'm not exactly sure where it is but if you can't see it behind the covers under the dash, it might be behind the glove box. They're usually semi-accessable.

Click to expand...

Thank You! :cheers:

THAT is the info I was looking for!

Anyone have a diagram?!?!?! Pictures?!?!?!

Tall Shadow

Tall Shadow said:

Thank You! :cheers:

THAT is the info I was looking for!

Anyone have a diagram?!?!?! Pictures?!?!?!

Tall Shadow

Click to expand...

I'm also looking for this! same problem.:hang: Its freezing and my heater conrtols went out.
any info will help. thanks

You're on the right track. You know the rad hoses are hot. Are the heater hoses hot too? In AND out! The thermostat gasket has a peculiar teardrop slot in it and you could have put in one that was not correct??????? I am in Royal Oak too, and have a 2000 XK. Hate to brag, because it probably will screw up if I do, but mine is toasty and warms up faster than any vehicle I had before. And holds heat longer than anything I had, like to go somewhere again in an hour or two. If you read enough of these threads, you will see that XK's also have a dreaded blend door (temp) breakage issue that cannot be fixed by the actuator (door motor). But some talk about a repair kit on Ebay that supposedly can fix it without pulling the dash and the HVAC unit as would normally be required to fix a broken blend door. I haven't dug into it because mine didn't break yet.

PM me for information about the Factory Service Manual.

The electric motor for the blend door you speak of is on the bottom of the heater box closest to the radio on the passengers foot well area. I am also having the same issue.. It gets luke warm in the jeep, but Im also having a warm on drivers side/cold on passengers side issue as well.. I love the jeep, but have never had a car that blew this cold of heat before. Please let me know if you find anything else out TALLSHADOW. I'll do the same..

What brand thermostat and what temperature degree do you have installed?

Blaine, it doesnt seem to matter.. When I bought my jeep, the previous owner told me that he did the waterpump/thermostat. I could tell he had since there was blue rtv everywhere.. After noticing no heat and it sucking, I decided why not buy a 195* thermostat and change it just to make sure it couldnt be that he's got a 160 or it being stuck open. Still its colder than an eskimo's +i+ in the jeep.

Tall_Shadow,

This is a long shot, but you might see if the heater works better (after reaching normal operating temp) with the hood up.

See, I had the same issue as you when I replaced all my hoses...come to find out...the top heater hose was getting pinched by the hood and the valve cover. It was a OEM preformed hose, but had to trim it at the end that attaches to the water pump so it sits down lower below the hood.

Just something to look at...

good luck.

I was using an AutoZone thermostat once. Motor got up to operating temp but I had barely any heat.

I can't explain that one because the motor was hot enough.

But after that I tend to always ask what brand thermostat people have installed when they have heat issues.

Blaine, that seems like a stupid coincidence since the thermostat only regulates the engine getting up to temp and helps it stay in the correct range.. So you're saying that after going to a jeep thermostat your heat was good?

Im not 100% sold that the blend door is broken since I do have control over heat and I can watch the actuator motor on the bottom doing the sweep.. It does change the temp at the vent, just not super warm. Also I dont see how the blend door would explain the split vent heat (drivers side warm, pass. side cold), especially saying that the cherokees weren't split control drivers/pass like the Grand Cherokee's.

Tested my vent heat to see if they were all like that and mine is hot on both sides. And the blend door motor can move, but the shaft behind it broke. You have to pull the blend door actuator motor and feel how the shaft moves by hand.

Mikes99XJ said:

Blaine, that seems like a stupid coincidence since the thermostat only regulates the engine getting up to temp and helps it stay in the correct range.. So you're saying that after going to a jeep thermostat your heat was good?

Click to expand...

Yes, I have no idea it doesn't make any sense.

Actually I switched to a Stant Superstat thermostat and everything was back to normal, I'm using an OEM Jeep thermostat now.

But yea the thing about no heat and the AutoZone thermostat and actually being at operating temp, blows my mind as to wtf!

So, I just pulled someone out of a 6ft deep center median ditch and I think I realized something. at some point in the midst of things I was head on up the hill at about a 45* angle. After pulling out the Grand Prix I stopped at the gas station since I needed gas and to fill the washer fluid and noticed the radiator drank a ton out of the overflow. I think that when it was head on up the hill at approx a 45* incline it squeezed an air bubble out of it. Now the heat is quite hot, still havent figured out the no heat on the passenger vents, but the luke warm symptom from the drivers side vents seems to be gone. Something to try.. fill the overflow a good 3/4 of the way and run the car on a great incline, say 45* to try to get any air out of the system (possibly in the heater core). The best way to do that would be with a lift and then just lift the front of the vehicle quite high.