stoneattic

Is the engine getting up to temp? If the t-stat is stuck open because it's bad or there's crap keeping it open (or it's a MrGasket t-stat) it will flow too much when the engine is cold and it will never get up to temp and you'll see the no heat symptom.

clarkd

Mine doesn't have that. I think that is how the older model (84-96) worked which used a vacuum pump to control the heat. Now the hoses go straight to the heater core from the thermostat housing and block. Here are two pictures to show where the hoses go on this one.


Here are the two hoses going into the heater core.


Here you can see where the upper radiator hose and the hot heater hose go into the t-stat housing. The rusty thing at the bottom is where the heater return hose goes to.

As you can see...there is no valve in the engine compartment anymore.

Yes the engine is getting up to temp, and the thermostat seems to be working because the upper radiator hose only gets hot after the Jeep hits about 210, and it warms up quickly once it does.

rhamby053102

Hi,

You probably won't like hearing this....but, most likely it's broken blend doors. Just bought a 2004 Grand Cherokee for my wife, got a really great deal on it because the heat didn't work. After doing some research I found this is a common thing on 99 - 04 Jeeps (all models). They even redesigned the parts to fix the issue, but have not issued a recall. To fix it the right way the whole dash has to come off. Here is a great time lapsed video link of the exact repair needed.
I'm glad the dealer we bought this Cherokee from put it in writing that they would fix this.....thank god!

greenjeep23

Well I got a heater problem too, it don't shut off. It's not bad now but heeeellllloooo this summer.

boyesreef

for the initial poster. i had a VERY similar issue. radiator was empty, poof of smoke, no heat upon refill. what it ended up being was the PO used stopleak for a small hole. it got cold outside and the stopleak scab came off the inside of the radiator, went through the heater core and got stuck, blocking flow. so i refilled the system, reapplied some stopleak (lets face it, im cheap) and let the jeep run for about 45 minutes. it melted the original chunk and TA DA, heat!

captainwoot

The op's post about the wj is very true , they are prone to heater failures, the xj on the other hand very rarely breaks blend doors. Try flushing your heater core with CLR , garden hose and hot water. This should help, I have even used acid(used to clean alloy wheels) very carefully and had good results.

clarkd

Here is an update since there are more posts on this.

The last thing I did was disconnect the hoses to the heater core and attached them to a drill pump so that the fluids would flow in reverse and just through the heater core. Unfortunately, I was trying to use a cordless drill, and it was ridiculously cold outside. Those two factors made it so that I was only able to push the fluids through for about 5 mins (helps if you charge the batts). However, the heat is now luke warm (which is better than no heat), and my "pre-wife" is happy enough for now.

When it gets warmer I plan to flush the entire system again with more focus on the heater core, with a corded drill, and in both directions; and the heat should hopefully be fully restored. To make things even easier I installed a second tee so that I can use some hose pinch off pliers to separate the heater core from the rest of the system without too much hassle.

00silverxj

you said that you discovered your fiance's jeep had no antifreeze...
what caused this?
you might check the water pump-a lot of times when they go bad, there is a little weep hole that will leak, effectively draining all coolant out of the system. plus, when you refill it even changing the thermostat, if the water pump is bad, it still won't pump coolant which will not send hot coolant to the heater core. If the heater core never gets hot or even warm...you will not have warm air coming out of the vents.

jeepweezer

In my YJ after changing out the water pump I had the same problem and it turned out to be junk in the heater core. So in about 20 degree weather I had to flush out the heater core. Do no use a high pressure pump or you can blow out the heater core, just use house water pressure if it is decent enough. I ended up flushing a bunch of rust chips from my heater core and the heat works great.

brandon402

Looks to me like the previous owner did a little modding. You dont have a heater control valve at all. Looks like someone installed one of those easy flush fittings on there in its place.

clarkd

A few responses.

I don't think the newer XJs have the same type of heater valve as the older ones. Unless my temperature control has been working on magic.

I added the tees since I am a newbie, but I am quite satisfied with them. In fact I added another to the coolant return so I can to a flush of the heater core without as mush hassle.

Not sure why there wasn't any anti-freeze, but I have been checking the coolant level since the original flush. The level did go down a bit, but I cheated and just topped it off. If I have to replace anything else I am going to wait until spring. However, I was concerned about the water pump, but it seems to be working (made sure that the hoses tightened up when the Jeep got up to temp).

Therefore, I won't really have too much more to post until about March or so. Then I'll see how this drill pump idea works out. Again this is a simple pump that uses a drill. I doubt it is putting enough pressure to break anything. However maybe if all else fails I'll shove the end of a pressure washer down one of the hoses and let it rip.

pierre

p

JSmith0055

i had a similar problem, try bypassing the heater core and seeing if the heater core is part of the problem, take out the thermostat to see if thats causing it, mine ended up being just the water pump not being able to pump the antifreeze, but the coolant systems on these things have many problems. and the blend doors for the heat are known to break or get stuck on these as well

clarkd

Ok here is an update. Two weeks ago the jeep started acting up on my fiancee while I was away, so her dad took it to a mechanic. Apparently, there was more junk to flush out. Well the guy was able to clear out the heater core (heat is back to normal), but he insists that the radiator needs to be replaced which I think I agree with since it is probably packed with the orange gunk.

As for the source of the orange gunk...probably just rust in the water jacket of the engine, and the cooling system just needs to be flushed more often. However, it is now over heating more often, and coolant is coming out of the overflow when it idles. Is it possible that the junk that is still in the system is killing the thermostat, and that this won't stop until the radiator is replaced? I am also thinking that since there is junk in the radiator it is killing the coolant capacity of the system and that is why when we top it off (when it is cold) it overflows when it gets hot and expands.