Heater Only Works If I Rev The Engine
 

I have a Town and Country, 2005 year model, Touring edition with the 3.7L engine. Recently, I noticed that the heater was working sporadically. For example, if I let the van warm up on a cold morning in the garage, the heater never gets hot...the air coming from the panel or floor vents is cold. But, once I start driving the van, the air warms up but as soon as I slow down or let off the accelerator, the air gets cold again.

Tonight, I tested this by starting the van and letting it idle for about 10 minutes. The temperature gauge on the dash was between hot and cold, the engine block was hot, and the heater was full blast on high temp but the air coming out was cold. As soon as I revved the engine, the cold air changed to hot air. Within 15 seconds or so of the engine returning to idle speed, the heated air once again became cold.

I have topped of the cooling fluid so I know for sure I am not low. I can squeeze the heater hoses leading into the firewall but they do not seem full...rather soft and squishy. At idle, they are not even warm to the touch.

Does anyone have any ideas what is going on here?

Thanks.

low coolant in the radiator? did u just fill up the over flow tank

possible broken thermostat

Those symptoms all sound as if you don't have a cooling system full of coolant.

Since it the seasons have changed recently you may have had a problem longer than just recently but you weren't using the heater and didn't notice the change when it occurred.

If the thermostat has failed or failed partially it could cause a low coolant situation and then cause the system to get air in it. With air in the system it won't allow the coolant to flow through properly. And with a low coolant situation you won't get much heat out of the heater.

"If the thermostat has failed or failed partially it could cause a low coolant situation and then cause the system to get air in it. With air in the system it won't allow the coolant to flow through properly. And with a low coolant situation you won't get much heat out of the heater"

THIS IS NOT CORRECT INFORMATION

Incorrect informatoin--how so?

Low coolant will result in poor heater performance.

A failed or partially failed thermostat can cause a low coolant situation.

A coolant system that has not been properly bled of all the air will cause poor heater performance.

The low coolant yes is the only viable reason and I already said that in my first post the broken thermostat will not cause low coolant in a sealed system only a leak will do that. The broken thermostat will cause the coolant temp to drop but not cause air in the system.
The only why that U would have air in the system is if A a leak or B it was open up and air introduced .

:D Mark it Solved!

The coolant level WAS low so I added some....but only to the overflow (duh). Once I went back and topped off the radiator, the heat came back to life and all is working well.

Thank you for the help. It saved me a huge headache.

U still have a prob though U have a leak some where more then likely the water pump is leaking.

I think you are right about the leak. Several times this summer, I noticed a puddle on my garage floor that was in the vicinity of the left-front tire. It looked like it had anti-freeze in it but I never could find a leaky hose and the leak (or at least the appearance of the puddle) wasn't consistent. Where is the water pump? Is it near the front-left tire? Are their additional signs or sounds I should look for?

Thanks!

right front tire near the belts back half if U are under the van u would see orange cruse around the water pump area