No heat

[hoov99]

2009 Fusion 3.0 with automatic climate control. Problem is when idleing there is no heat. When I give the engine some revs it starts to blow heat but when it goes back to idle, the air goes cold again. The coolant tank is full and there are no coolant leaks. What could be the problem?

[xmech2k]

Strange how it's associated with revving. I guess it's pretty cold there now. How's the engine coolant temp?

[awdpath]

2009 Fusion 3.0 with automatic climate control. Problem is when idleing there is no heat. When I give the engine some revs it starts to blow heat but when it goes back to idle, the air goes cold again. The coolant tank is full and there are no coolant leaks. What could be the problem?

 

Very likely just need a burp or two then top it off. Car under warranty? Just let the dealer/Ford deal with it if yes.

Edited January 8, 2011 by awdpath

[hoov99]

it is cold here this today. about 15f. the engine temp gage is in the normal range as usual. could it be the thermostat stuck open? would a stuck thermostat make the temp gage read different? the car is out of warranty because of the 50,000 miles. i do have it scheduled at ford for wednesday but im afraid of the cost to repair. just hope it has nothing to do with the auto climate control. im assuming it has to do with the flow of the coolant because at higher rpm there is heat but when at a stop light or driving in slow traffic it goes cold.

[xmech2k]

I believe a stuck thermostat would make the car run cooler and take much longer to get up to temp. (I was thinking of asking if you had removed it, as I hear plenty of people do, but I think it's a bad idea.) They can stick open as well as closed, but like I said, I think you'd see the temp gauge doing unusual things.

 

I would think if the system needs burping, you'd be getting the waterfall, gurgling sound effects, too.

 

My first guess would be in the auto climate control, although I don't know why the engine speed would effect it, but I'm an aircraft mechanic, not a car mechanic, so until someone with specific knowledge chimes in, that's my best guess. I know it's not much help, just no one else jumped in yet, and maybe discussing it will draw out a good idea or something. Hope it's a cheap fix!

[akirby]

I've heard of stuck thermostats causing it. At idle the coolant just isn't warm enough until you rev the engine which adds more heat. Easy enough to test and fix. Other than that I'd say it was a flow problem into the heater core that gets fixed with higher RPM and faster water pump operation.

[hoov99]

how do you burp the cooling system?

[xmech2k]

Here's how a guy did it in the 'gurgling' thread: Funnel method It's post #1010.

 

But I doubt it would be the case, or you'd hear the gurgling. I had my water pump replaced under warranty and had the gurgling noise on the ride home, then picking up my son from school, but it was gone the next day. There's no missing it.