Heat when sitting still

[alanmad]

I am having problems getting heat from my 99 caravan. I replaced the thermostat today but that didn't help. When I bought the thermostat, I was asked if I wanted the 192 or 182 degree one - I got the 182 degree one. Not sure if it matters.

After I replaced it, I warmed up the van while sitting in the driveway and the heat gauge rose to a warm temp. I took it for a drive but the temperature gauge moved slowly down to the coldest setting again. It seems that I have to be sitting still for heat to build up.

When I check my upper rad hose after a fairly long drive, it doesn't seem to me that there's a lot of pressure there. I can remove the rad cap right after I turn the engine and the coolant temp doesn't feel as hot as it should - I thought there should be a lot of pressure built up as well but there isn't. I read a similar post about bubbles showing up at the top of the rad, when I idle mine and take the rad cap off, I see bubbles as well. I also see the coolant seems to contain a lot of scaly material.

Does this still mean I have a defective thermostat or is there something else that could be happening?

Any suggestions on what to do next?

[HeadlessHorseman]

Why did you replace the thermostat to begin with? Was there some problem you were trying to resolve?

[alanmad]

Originally Posted by HeadlessHorseman

Why did you replace the thermostat to begin with? Was there some problem you were trying to resolve?

Yes, the problem was that my temperature gauge never went much beyond the cold setting and I wasn't getting heat.

[uplandhunter]

I am having the same exact problem with a 1994 Grand Voyager. I went with the 192-degree thermostat (what a peach that little sucker is to replace!) and even replaced the radiator cap. Still no pressure in the top hose and no heat! I am wondering if the rear heat might not be causing the problem? Isn't there a separate heater core back there?

In our case this is something that just came up about two weeks ago…she says it just quit blowing warm air and the gauge drops to cold when she drives. I checked the fan and it ain’t on…so I know were not pulling frigid air through the radiator.

Could we have air in the system? If so how do I get it out? I have let the motor run until the thermostat opened…done this with both the radiator cap on and off and coolant level seems ok either way.

I am at a loss….HELP!!!

[HiRez_L]

Could be the haeter core, I'd try back-flushing it.

[uplandhunter]

Would a guy want to just disconnect the hoses and flush it (heater core) with water or is there a better way to do this?

[technican]

I've owned 3 caravans with the same heat problem, little or no heat at idle and reduced heat at highway conidtions. after changing thermostats , water pumps rad caps and checking the air conidtioning valve I discovered it is in the heat control (slide bar for hot cold). the door is not closing all the way. allowing cold air to mix with the hot air. the cable has to be adjusted hope this helps

[scottw]

That happened to my 99 last winter, it was the water pump.
Parts and labor at the dealer was $259.

[HiRez_L]

I just use the garden hose when I'm back-flushing. Of course, that doesn't help when it's below freezing outside . . .

[wrightbrigade]

Originally Posted by uplandhunter

Would a guy want to just disconnect the hoses and flush it (heater core) with water or is there a better way to do this?

Thats the best way to flush the heater core. You can install the flush kit sold at auto parts stores. That will flush the whole engine. Problem is it gives you a couple more places for leaks to develop. I'd just pull the hoses and flush that thing.

[wrightbrigade]

Originally Posted by alanmad

I am having problems getting heat from my 99 caravan. I replaced the thermostat today but that didn't help. When I bought the thermostat, I was asked if I wanted the 192 or 182 degree one - I got the 182 degree one. Not sure if it matters.

After I replaced it, I warmed up the van while sitting in the driveway and the heat gauge rose to a warm temp. I took it for a drive but the temperature gauge moved slowly down to the coldest setting again. It seems that I have to be sitting still for heat to build up.

When I check my upper rad hose after a fairly long drive, it doesn't seem to me that there's a lot of pressure there. I can remove the rad cap right after I turn the engine and the coolant temp doesn't feel as hot as it should - I thought there should be a lot of pressure built up as well but there isn't. I read a similar post about bubbles showing up at the top of the rad, when I idle mine and take the rad cap off, I see bubbles as well. I also see the coolant seems to contain a lot of scaly material.

Does this still mean I have a defective thermostat or is there something else that could be happening?

Any suggestions on what to do next?

I'd put the hotter t'stat in, won't hurt a thing. Also let it idle for a good long time with the cap off, the t-stat will open, the coolent level will drop in the radiator, add fluid, wait till almost all the bubble are gone. The system is bleeding air out. ON a cold day this may take a hour. Fill the overflow tank to cold. Check the cable mentions in this forum that goes to the heater box under the dash, follow it from the control to the box and fell for a lever make sure it's all the way shut in both hot and cold air mix. Your water pumps impeller may be broken inside the housing and not pumping coolant. Remember to mix coolant with water 50/50 for cold weather protection. Hope this helps.

[uplandhunter]

Thanx guys.... we have gone through everything but the cable on the heater.

I just gotta tell y'all about running that thing with the radiator cap off. I feel kinda responsible cause I told her to do it. Anyway, she starts the van and (I should have said not to rev the P*&^ out of it) she runs it up to about 4 grand and holds it there; or so she says. Well to make a long story short...we had an air lock in the motor from when I changed the thermostat. And when it broke loose she said coolant came out of the radiator and shot up into the air about 5 feet! Which brings to mind...who invented them damn serpentine belts? I'd like to slap him!!!
When the van went off like Mt. St. Helens...the coolant hit the belt and popped it off its pulleys! Oh well 10 minutes and three frozen fingers later…I got’er done and back together!

Now onto the next question: How is that cable from the control unit to the heater box attached? Is it just a setscrew kinda thing or will I need some special tools to adjust it?

It’s gotta be that cable…GOD please let it be that cable...that woman's feet are cold enough as is!

[HiRez_L]

I hope it's done better on your 99 than it is on my 94 . . . the door wasn't working on my 94, and we had to take out the whole dash, strip it down to the firewall to get at the innards of the ductwork. On mine the cable entered the ductwork through a little hole by the drivers footwell, when we got it all apart so we could remove the top of the ductwork, the cable went through that hole and attached to the door with a ball on the end of the cable that fit into a little plastic catch on the door. On mine, the plastic piece was broken off, that's why it wasn't working. Dealer wanted $45 for a new door, and it was pressed in, after looking at it closer, it didn't look like I could change it without breaking something else. So my best friend and I fabricated a new catch out of one of those little stamped metal pieces they use to attach coaxial cable to the side of your house, and screwed it directly to the door, which also gave us the ability to adjust it . . . That was about a year ago, and it's worked flawlessly since. And the whole repair didn't cost a cent, though it took a full 8 or 9 hours to get it all apart, fabricate the new catch, attach it, and get it re-assembled.

[amoto]

I just took my '99 T&C into the dodge dealer this morning for a similar problem.

It would not put out any heat at idle, but when I started driving, it would warm up. If I went back down to an idle, it would cool off again.

I figured it was some sort of air in the lines, since I had done a coolant change a month or so ago.

Since I had to take the van in for the recall on the clock-spring, I figured I'd let them at least diagnose the problem for me.

Turns out the coolant level is low due to a leak in on of the tubes running to the rear heating system. The estimate for repair is $725!!!

I think for that price, I'll try to fix it myself...

Does anyone know if there is anything special about the heater tubes running to the rear of the van? Is it an odd metric size? Any problems with replacing it with rubber heater hose?

Thanks
ANdrew

[noslolo]

WOW that is the exact same problem that I'm having. I went to flush the system and found that the rear lines were leaking. It is only a couple of days away from Christmas so I don't have a lot of time to tackle this right now but I need to get it done soon due to the fact that I drive my 94 to MD every week. Any info on the price of lines or how hard they are to replace. Thanks in advance for any help

Originally Posted by amoto

I just took my '99 T&C into the dodge dealer this morning for a similar problem.

It would not put out any heat at idle, but when I started driving, it would warm up. If I went back down to an idle, it would cool off again.

I figured it was some sort of air in the lines, since I had done a coolant change a month or so ago.

Since I had to take the van in for the recall on the clock-spring, I figured I'd let them at least diagnose the problem for me.

Turns out the coolant level is low due to a leak in on of the tubes running to the rear heating system. The estimate for repair is $725!!!

I think for that price, I'll try to fix it myself...

Does anyone know if there is anything special about the heater tubes running to the rear of the van? Is it an odd metric size? Any problems with replacing it with rubber heater hose?

Thanks
ANdrew