Hey Everyone,

Need a little help with this thing. I am getting very little heat from my 01 Grand Cherokee 4.0L. Just enough heat to keep the inside of my window from freezing over.

Not sure if it means anything but I DO NOT have dual temp control, just single.

Two issues that I have.
1. Blower motor only runs on low and on high. I kinda want to wait to fix, no heat = no need......
2. Tiny leak in the radiator. Darn thing...

So far I have tried:
-Flushing the heater core. To be fair its winter so no running water outside, I pored 3 gallons of hot water through the sucker (both ways) and even left vinegar in it for about an hour (in the hopes of breaking anything up). I got no gunk or deposits at all, nothing I noticed at least.

During the flush the water ran through "fairly well" I'm not really sure how much flow should be there. For sure its not "saturating" the hose.

-Blend Doors. Last night I broke down and decided I would check them. (I had always thought they where fine) and of course they are working fine.

-Heater Core Hoses. Both of them get hot. If I get to temp, turn the fan on high and feel them then one is hot and the other "less hot"

-Bubbles. I have run and re-run and re-run the procedure to make sure everything is full, and like I said, both hoses get hot.

-Thermostat. Replaced, wasn't needed, but I was getting some leaking from the gasket so I replaced the gasket / thermostat at the same time. Engine has been running slightly cooler since it was replaced.

That is it, I'm out of ideas. I have searched and searched and have not been able to find anything else online. At this point I'm going to buy a heated seat cover so I can survive the rest of winter. -15 F coming next week, Arg!

Any ideas?

 

First of all, welcome to CF! There is a wealth of information here if you do a little searching and reading posts. When I bought my 97 ZJ I was clueless to problems with Jeeps and I got an education fast!

Having said that, I own a 2000 WJ (GCL) and have been having the same problem. I think my problem is the thermostat because when it gets VERY cold, the temp guage doesn't get up to normal, yet does when the temp is around 32* or higher.

I think mine is a 210* stat that's opening too soon.

 

Been thinking about it all day, starting to think its a flow issue.

Thoughts on compressed air? I have a tank that gets to 100 psi. I've searched and there seems to be 2 camps, lots saying it works and is safe, and a few saying it will damage things, but I have not seen anyone saying it actually damaged theirs.

Any ideas on a procedure for this? DO i try and get all fluid out first?

 

If you're talking about blowing the heater core out with air, forget it! the brass wafers that make up the core are paper thin and are easily damaged. I wouldn't go beyond garden hose line pressure or whatever the radiator cap pressure rating is. I know it's cold out, but do it in a heated garage. If you have access to a washing machine set up, You can use hot water. I was looking at mine, and the hose from the thermostat goes to the bottom of the heater core so it will vent the air to the water pump. If you flush it with hot water, put the hose in the top so it reverse flushes the crap out. You might want to replace the heater hoses because they can get soft inside and effect the flow.

I really don't know what's going on with mine. Tonight I was out on the newspaper route delivering marketing circulars and the air temp was -2*. The engine decided to run at 210* and the heat worked great, although driving with the window wide open didn't help me to stay warm! The upper corners of the windshield froze up, but the rest of it was fine. We just got 6" of lake-effect snow but the Jeep powered thru like a tank. It's 2 AM now and the plows are just starting to show up and it's still snowing.