Heater issues

morkable

morkable

Just Over Broke
Joined
Jan 30, 2008
Messages
5,956
Do any of you have a intimate knowledge of the HVAC system of a 07 King Ranch?

Here is my problem,,, I will be driving along and everything will be just dandy, nice heat everything is great. Then all of a sudden it will start throwing cold air out,, and I mean really cold. Kinda seems like it will do it when the temp changes while you are driving.

Are the blend doors controlled by a computer? Is this computer tied in with the outside temp probe?

Any help on this would be greatly appreciated
 
Not good. This happens quite often when you lose head gaskets. Cooling system gets pressurized and wont flow thru heater core. Make sure the plastic valve with the vacuum line is hooked up in the heater hose by passenger side oil fill tube.
 
the heat is good, temp gauge sits exactly where it is supposed to. No other issues. It really seems to be related to the temp outside,, if you go through a pocket of colder air, it will suddenly start blowing cold air in the cabin for awhile till you get into the warmer air again,,, it is really weird.

I can go for 200 miles without a problem,, then just bang,, it is blowing cold air... and by cold, I mean outside temp cold,, see my breath cold
 
Nobody have any ideas? Can anyone tell me if the outside temp probe has anything to do with the heating system?
 
Engine temp gauge on a Ford is about as accurate as the oil pressure gauge on a Dodge lol. Most of the temp gauges are just a computer calculated reading based off transmission temp. Does adding a winter front change anything?
 
I havent tried that... but the heat doesnt seem to be a problem... it is really weird, just driving along, everything is beautiful,, and boom, it is blowing frigid cold air.... then all of a sudden it is back to nice heat.... sometimes it lasts a few seconds, once it lasted over an hour
 
The digital control panel the KR's use are known to go bad and do funky stuff.
 
Sorry for being off topic but happy birthday Kevin. Would the heater core be going?
 
So Josh, what you are saying is that the HVAC is actually computer controlled?

Thanks Huck,, I appreciate it... no heater core is fine, the heat is beautiful, and no smell at all
 
Kinda, that control panel is a computer in itself. It controls the vacuum actuators that run the dash though all its motions. I would check your vacuum pump and lines to make sure you are not losing that before going much further. The pump is electric, mounted on the right inner fender just ahead of the blower motor.
 
Thanks Josh,, good info... I was kinda thinking there had to be something controling everything,, it really seems to be tied together with the outside temp, which would make sense,, computer glitch,,, lol
 
Yep, best thing is to hit it with a scanner and see if it has any codes setting on hvac.


Oh, happy birthday you limey canook.

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Ok, I have been trying just anything, and I have stumbled on something that seems to work... I put a peice of cardboard over the main part of the grill.. and presto we have heat. So now my wife has heat at highway speeds, but when she slows down it will start to get cold again. I am thinking it is the sensor that tells the outside temp. Can anyone explain to me why the truck would use this data for cabin heat?
 
It was perfect, now it is a little higher than my liking with the cardboard on there... still not in dangerzone or anything.
 
Have you tried a new thermostat? They are known to get hung open ever so randomly
 
I assumed you checked the coolant level? Also the front hubs are known to have vacuum leaks that come and go at speed. Plug the vacuum lines going to the hubs and see if the heat issues go away.
 
Temp sits just perfect, never moves, so I would think that it is fine... and now that i have put cardboard over the grill it makes heat again, just like it is supposed too... I am pretty much 80% sure now (after a LOT of reading on the internet ) that the problem is the outside air temp sensor.
 
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