I am having problems with my heat. when driving the truck i have great heat but at idle cool air.dealer says it is a partially blocked heater core.Is this true? I have had this back to the dealer 5 times for the same thing. The first time they said it was just low coolant.they added coolant and it was fine for about 2 weeks.back again they added coolant and looked for leak. replace resuvouir and cap. still had problem.they told me to keep a eye on the coolant level and bring back if it goes down. I noticed white spots all over the res.tank and took it back and said there is no heat at idle. now they are telling me it need the heater core. I think they are just guessing. what can i do if they replace core and still have the same problem? nothing ,pay and go on to their next guess. I had this problem with them before. my truck kept pulling to the right when hard braking. 1st they replaced pads. no good. then calipers. still pulling. i finally gave up.tired of dumping $$$$. i take it in for inspection and they find a bad drag link and what do you know it stopped pulling. I tried to argue with them telling them i wanted some money taken off the bill for the pads and calipers replaced for nothing but they did not want to hear that.no money off. now back to the heat. what should i tell them about replacing the heater core. If that isnt the problem i want my money back????? please help!!!!!!!!!! sorry so long but i have had it with the dealer and their guessing!!!!!!!!

 

First of all, STAY AWAY from that dealer.
Is it possible you have er, um, blockage?
Sure, it's possible...
Try a flush then add decent fluid.
Put in a 203* thermostat along with a top hose that goes outside the belt.
May as well replace the bottom hose too...

Report back...

 

the dealer has it now. what do i do if that doesnt fix the problem? or is that def. the problem?

 

That same dealer has it? What are they doing with it? Cuz I agree with Steve_250

 

Sorry, but I don't have my Captain America Personal Decoder Ring, Ford recalled it.
I wouldn't even attempt to say it is definitely the problem.

These are things that are part of a maintenance program, your's or Ford's.
Belts and hoses need periodic replacement along with fluids.
With your mileage, it's time to do it if you haven't already.

If you do it and it doesn't fix the problem, no loss, it needed it anyway.
But on the other hand, perhaps it IS the problem.....
Not a sermon, just a thought.....

 

I'd check into a vacuum leak.

What engine is it? Diesels have their own vacuum pump.

When the "air goes cold", does the air still come from the floor? Or does it come from the defroster? Does the air suddenly go cold as soon as it hits idle, or does it take a few minutes before it goes cold?

Depending on the truck, and if it's a gasser, you might have a heater core cutoff valve, and combined with a vacuum leak, the core might be shutting off. But that would also send the air through the defroster. However, the cutoff valve might be stuck halfway too...

However, to check for a heater core blockage, just disconnect both ends of the heater core and push water through it with a garden hose. If you get a good flow of water, it's fine. Better yet, if there's anything in it, you should see crud come out if you backflush it. Which is also maybe just what it needs.

 

Please report back when you do get it figured out.

My 05 F-350 w/6.0 does the exact same thing...I've lived with it because I primarily use my truck on the open road so it doesn't get a chance to idle that much when I am in it...so you aren't the only one with this problem.

thanks.

 

it is a diesel. it takes a little while before the air cools down coming out. it doesnt matter where I have it set defrost,floor,floor/dash or even just vent. when i am driving it is hot. I also have this little whistle sound I am starting to notice now when i give it gas and let off the throttle. It is hard to explain. if i give it constant throttle it has a kind of whistle about every 7 seconds. then i can get it to do it when i just floor it and let off it is a longer whistle. No, its not the turbo, I know what that sounds like its something else. as far as flushing it out,dont you think the dealer would try that? I guess they hookes something up to the heater core to check the flow and I guess that is why they are saying it need a new one.unless they are just guessing.Krewat, is there some way we could talk back and fourth about it instead of like this? maybe on aim or something. anyone that could answer,really, my screen name is the same hbronco96.Thanks!

 

I have an 04 F 350 6.0l and it doing kinda the same thing. Mine blows heat only when pulling a load on a steep grade after that it kinda warm air. It's been real cold here l8ly,
-12* C, so I am gonna try the old cardboard in front of the radiator. I looked under there this morning and there seems to be a lot a radiators. I assume one for engine and one smaller for trans but there seems to be a third full sized rad as well. What's up with that? I would be interested in what you may find out hbronco, post back if you get some answers.

 

Sounds like you may have an intermittent vacuum problem under the dash. Would explain the noise and the changing heat/cold. Could be just enough to hold the defrost door in position, but not the heater door.

 

I doubt it's a vacuum problem, since it's a diesel with an electric vacuum pump that doesn't change with engine RPMs.

Mostly, yes, dealers just guess. They aren't about to spend an hour or two diagnosing an issue and not get paid for it - if you PAID for the diagnosis, and they came up with clogged heater core, well, maybe they actually did the work to figure it out. Otherwise, they are just guessing.

What year, and what engine?