Heat only works when accelerating/cruising?

VoodooMann · **Posted:** Thu Oct 08, 2009 4:41 pm

If I idle my heat goes cold, simple as that, Jeep idles at about 600rpms, heat only works above approximately 800rpms...

Any ideas?

tjkj2002 · **Posted:** Thu Oct 08, 2009 4:44 pm

Low coolant level is your problem.Check for leaks,radiator side tank(drivers side top) and waterpump are the 2 biggest areas to check.

VoodooMann · **Posted:** Thu Oct 08, 2009 4:45 pm

all dry as far as I can tell, that was my first idea...

but you are incredibly helpful today!

RedKJ04 · **Posted:** Thu Oct 08, 2009 4:54 pm

If low coolant isn't your problem it could be that the heater core is getting clogged. Had a friend who bought a car that would only put out decent heat on the expressway. I pulled the heater hoses and back flushed and forward flushed the core with a hose and got all sorts of interesting looking gunk out. After that the heat would run you out at idle. Just thought I would include this tid bid of info in case your coolant isn't low.

Jeepjeepster · **Posted:** Thu Oct 08, 2009 5:52 pm

VoodooMann wrote:

all dry as far as I can tell, that was my first idea...

but you are incredibly helpful today!

Did you check the level of the coolant?

VoodooMann · **Posted:** Thu Oct 08, 2009 11:14 pm

I didn't realize it, but when I checked it earlier today it was 1/8" below the cool full line, and didn't even think to myself, I've been running errands for an hour...

I'm an idiot...

the coolant is low.

'DOH! :oops:

phluffhead · **Posted:** Fri Oct 09, 2009 5:32 am

now i question why is it low?closed system right?no burn off of coolant fluid, must seep from somewhere?

Jeepjeepster · **Posted:** Fri Oct 09, 2009 11:42 am

Fill er up with G05 only and go from there.

tjkj2002 · **Posted:** Fri Oct 09, 2009 8:54 pm

Fill up with the correct coolant and then pressure test the cooling system.

VoodooMann · **Posted:** Fri Oct 09, 2009 11:38 pm

how do i check the pressure, and where should it read?

tjkj2002 · **Posted:** Sat Oct 10, 2009 8:42 am

VoodooMann wrote:

how do i check the pressure, and where should it read?

Below is a cooling system pressure tester,can be bought at sears or online and pump to the psi that is stamped on the your radiator cap.

ridenby · **Posted:** Sat Oct 10, 2009 9:23 am

tjkj2002 wrote:

VoodooMann wrote:

how do i check the pressure, and where should it read?

Below is a cooling system pressure tester,can be bought at sears or online and pump to the psi that is stamped on the your radiator cap.

Also rented at advance or autozone

rt_power · **Posted:** Sat Oct 10, 2009 9:29 am

I think i have seen them some where else, but i just cant remember where :twisted:

LibertyFever · **Posted:** Sat Oct 10, 2009 10:09 am

VoodooMann wrote:

I didn't realize it, but when I checked it earlier today it was 1/8" below the cool full line, and didn't even think to myself, I've been running errands for an hour...

I'm an idiot...

the coolant is low.

'DOH! :oops:

Don't feel bad, we've all done it before.

I've since learned to start with the cheapest solution first. I once replaced a water pump to address an overheating problem that actually was caused by a bad thermostat :roll:

Boiler · **Posted:** Sat Oct 10, 2009 11:46 am

#1 thing to not do is accept this as a heater problem and take your time figuring it out. I had that exact same symptom with my taurus. I drove the rest of the way to work (5 miles) and then attempted to drive it home and it overheated. Honestly I'd forgotten about it on the return trip until I drove a couple miles. :oops:

VoodooMann · **Posted:** Sat Oct 10, 2009 5:16 pm

Alright, so I went and got some HOAT and filled her up, it was a lot lower than I thought, i was reading the residue in the tank. so I started her up, ran a few errands, came home, let it idle for ten minutes, turned on the heat and holy M#*&%^#$*(&% crap it was hot. i seriously checked my eyebrows. so i'd say the problem is solved. :lol:

thanks for the help guys...

the pressure check tool is already loaned out at my local advanced auto, so i have to wait to check it, but i did notice that the hose on top of my coolant tank does not have a clamp on it and every other hose does. and a tidbit of steam was coming out the seal. so I figure that is most likely my problem.

VoodooMann · **Posted:** Sat Oct 10, 2009 5:18 pm

Boiler wrote:

#1 thing to not do is accept this as a heater problem and take your time figuring it out. I had that exact same symptom with my taurus. I drove the rest of the way to work (5 miles) and then attempted to drive it home and it overheated. Honestly I'd forgotten about it on the return trip until I drove a couple miles. :oops:

my heat needle always stays below half, which is why I would have never guessed my coolant was low. so I have no Idea.

Jeepjeepster · **Posted:** Sat Oct 10, 2009 11:16 pm

Engine temp was probably just fine. When the coolant gets low it stops going through the heater core. Once it gets low enough it will start over heating though.

Try to pressure test it if that pump comes back and make sure you keep an eye on the level. It may of just needed to be topped off but thats not likely. Since its a closed system that much isnt going to just evaporate.

VoodooMann · **Posted:** Mon Oct 12, 2009 11:28 am

the thing is, the engine under the tank us dry, all the hoses are tight, there arent any puddles if my jeep sits for a few days. I just absolutely cannot find a leak.

i don't get it.

WolverineFW · **Posted:** Tue Oct 13, 2009 12:24 pm

If you are still losing coolant with no visible leak, you could have a head gasket leak with the coolant going into the cylinders and being vaporized. When the engine is cold you would be getting some white exhaust smoke if that was the case.

Heat only works when accelerating/cruising?

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