No Heat

[Marty]

Ok, will post new thread on this with bit more info.

Well, sure enough soon as it hits -15 C here, my heat gives out. Nothing comes out the vents after stationary idle for 15 minutes, then I get heat after about 10 minutes of driving. If I stop and park and keep idling, heat goes away, then comes back once I drive some more. Temperature gauge comes up to normal (1/2 way). Switching the control to defrost or air conditioning brings the a/c compressor on but still no heat. I checked the heater hoses and they only get semi-warm when idling.

No codes came up. Stuck thermostat? Temperature sensor? Needs full flush? Although it's a 2002, I'm only at 114,000 km, barely over 60,000 miles. Tonight temperature is -30 with windchill and I have to fix this...Probably will drop it off tomorrow and will post the fix once I know.

Ideas welcome, anyways, thanks,

Marty
_________

 

[Cableguy]

Coolant level? No obvious leaks anywhere?

The temp gauge comes up to half and stays there the whole time, or does it fall again when you idle?

Your jeep is just telling you to move south for the winter!

 

[JeepJeepster]

Check the Anti-freeze.. You may of done that when you checked the heater hoses though.

 

[hyde]

This problem seems to be getting very popular. You are the 4th person, including myself. I spotted a leak on my radiator, after filling up the coolant (when it was back down to low levels). I have exact same problem.

 

[Atrus]

My initial thought is that the heater core may be severly restricted but not fully plugged....At idle, the pump may not be spinning enough to get coolant flowing to warm the core. Cruising raises the RPM and enough pressure forces coolant through the core. I think the Jeep coolant is similar to GM's Dexcrap...err...Dexcool. It's designed to gel when it comes into contact with air to minimize or eliminate leaks. Get an air bubble into the heater core, and it'll gel and plug it up. A friend with a 1999 Silverado had this problem. Hoses going to the heater core were not hot. Pulled the core, flushed the hell out of it and he suddenly had heat again once the sludge was gone.

Idea #2 would be that perhaps a stuck thermostat is the problem. I don't think this is the case as you say the temp gauge is indicating that the engine warms up properly. If it's only the heater core not getting warm, it's not the thermostat. The t-stat would keep the entire system cold.


I really think the Jeeps are seeing plugged heater cores.

 

[2003KJ]

I'm with Kevin on this one on it being a plugged core. The reason it's so common as it's "that time of the year".....people start using their heat again, and come to find out, it doesn't work! Kinda like in the summer, I'll bet you'll see some posts about "my a/c isn't blowing cold anymore"

 

[twindragons187]

another common problem is when the rad gets low and you put more coolant into it, you end up with air pockets. usually on either side of the t-stat, which won't let coolant pass into the core for heat until you get the water pump moving at higher revs. there should be a bleeder valve at the highest most point of the coolant system, try bleeding it first. had this problem with my old stratus. turned out it was just air trapped in the system when there should be none.

 

[hyde]

how do we flush the heater core? is it a mess?

 

[Atrus]

Ah, very true ^^^^. I'd recommend bleeding it too, it's free and the easiest to do. Make sure the engine is warmed to operating temps (ensuring the T-stat is open).

Some vehicles (not sure on the KJ) don't have a bleeder, you just remove the radiator cap and let it warm up. It'll bubble out any air pockets. My wife's old GM J-body was like this. My GM W-body had a brass bleeder screw on the top of the T-stat housing (on the lower intake manifold).

 

[Atrus]

I suppose you could do a full flush on the cooling system as a whole (make sure the heater is on high and hot too!), but I am not sure if that's enough if it's plugged. My buddy actually pulled the heater core out and flushed it out in his utility tub in the house

 

[JeepJeepster]

Jeep uses G-05 coolant which has nothing to do with Dex-cool. So no worrying about gelling.

Check to see if the heater hoses going to the heater core are hot when the Jeep is up to operating temp. If they are, then you must have a problem with the blend door or the like, if they are not warm, then you are either low on antifreeze or something is stopping fluid from going through the heater-core.

It probably wouldnt be to hard to flush the core but Im not looking at my engine, so I cannot tell for sure.

Does anyone know if the liberty has a valve that shuts off the flow of coolant when the heat is not being used? It could by a vacuum leak which doesnt let that valve open when the heat is on, but idk if the liberty has one. When the rpms are higher, the vacuum could be higher..

Just throwing out ideas.

 

[Atrus]

Jeep uses G-05 coolant which has nothing to do with Dex-cool. So no worrying about gelling.

I thought this coolant had the same "anti-leak" properties. Not so?

 

[Marty]

Well, there were some right on posts on this. Turns out I had a small leak in the rad. But not bad enough to put any puddles on the garage floor. Weird, but there you go. I don't see why such a small leak would stop heat at idle, then allow heat to get generated while driving?

I'm still a little suspicious of the dealer's diagnosis because I drove it for 3 days like that, I checked the antifreeze level every day and the day I took it to the garage, the level was at the "cold" level, when cold. They said it was dry in the reservoir and the thermostat was good. Hmmm. I have yet to pick up the vehicle because I'm travelling so we'll see in a couple of days.

 

[hyde]

Cool. Marty... How much!? I am dropping off my Jeep tomorrow with EXACT same issue, with LEAK in the radiator, and no heat at idle/slow driving. I just need to be prepared on how much this crap is gonna cost me... or if rad should be under drivertrain, since I didn't smash it.

 

[JeepJeepster]

The heater core is fed right out of the Reservoir. If its low at all, it will suck air right into it. Look at the hoses coming out of the tank and how they feed the heater hose, you will see what I mean.

At idle, the water pump is not pumping near as much coolant. When moving, the engines RPMS are higher which means the water pump is turning faster and moving more coolant. I bet if you rev the engine when sitting still you get heat.

 

[hyde]

You asked that before Blake. Yes, if you rev you will get heat, but not when it is already cold. If it already blew heat once, revving will work, but not when it hasn't blown heat it won't work.

I also noticed it is blowing much hotter heat than normal.
And also my heated seat isn't getting as hot as it did before.. That was strange.. Sometimes it would burn my ass, sometimes it just stays warm, not even hot..

 

[hyde]

I just dropped the jeep off, $188 two hours labor minimum, and they may need more time to do the fixing.. DAMN. What is wrong with these dealers? I will be picking up later today.

 

[tan's2002kjlimited]

Got behind the wheel this afternoon; fired up the heated seat, and proceeded to drive to the store in the icy, sleety, snowy day we are experiencing today. butt got nice and toasty, temp guage stuck itself right at 12 oclock, but nothing but BRRR coming from the heater. Came back home, and poured in almost 3/4 of a gal of 50/50. Then finished my errands.
Heat came back, I'm wondering where the AF disappeared to. Never saw any leaks.

 

[hyde]

I never saw any leaks in the beginning either. Check back in about a week to see if AF is lower.

 

[WalkGood]

Does your exhaust look especially "steamy"? Lots of water vapor?

The coolant could be being sucked into the intake system, where it gets burned into the combustion chambers. Kinda like alcohol injection.

You could have a crack somewhere (lifter valley in block as example) or a bad gasket where the coolant is misting into the PCV valve or under the valve covers. The PCV system ***** it in and you never see a leak.