Last post on Oct 11, 2012 at 11:10 AM
You are in the Ford F-Series
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Ford F-150, Ford F-350, Ford F-250, Heating / Cooling, Truck
#1 of 84 '99 F-150 climate controls prolem
Oct 10, 2006 (11:48 pm)
I need a direction to go before i dig into this. I have a 99 F-150, standard cab with the V-6. I have a problem with the climate controls. The Fan Blower works in all speeds. The A/C works, and the Heat works. But no matter where i turn the far right knob(to tell it where to blow i.e floor, dashboard, vent etc...) it always comes out the defroster vents. It will blow A/C and heat, but it will only come out of the defroster regardless of setting. Any ideas.
#2 of 84 Re: '99 F-150 climate controls prolem [jetmech_63]
Oct 12, 2006 (1:42 am)
You have a vaccuum leak. The air diverter in the dashboard that directs the air around for the different settings is vaccuum actuated. The default position (and for safety's sake ) is Defrost. Either the vaccuum line that goes into your climate control system has fallen off or is leaking. Or you have a bigger vaccuum leak somewhere else on the engine that's not allowing enough vaccuum pressure to get to the control and is affecting your vents.
Start checking all the lines - look for obvious disconnected lines, then check each one for holes or cracks. The vaccuum lines should be smooth and pliable. If a line line is stiff, brittle, or cracked replace it.
Not sure about your model F-150, Ford may not use the typical black rubber vaccuum lines to go to the climate control on your truck. It may look almost like its colored wire about a quarter inch in diameter going up to the climate control air box up on the firewall.
#4 of 84 heat and ac problems
Mar 13, 2007 (6:39 pm)
i have a ford 2001 f 150 truck. Just recently my ac and heater started to have a problem. When my truck is running i will have my ac dialed in to cold but every 20 to 30 seconds i can feel the heat come through then it will go away. I disconnected the climate control knob so it will hopefully not fluxtuate.Its kinda workin i have ac on the two closest vents but the other two closest to passenger has a slightly warm air coming through.Also when i did have the climate control connected I would have the truck running in idle i can hear what i think is the blender door moving even when the climate control is stationary. Need some opionions on what might be wrong. Thanks
#5 of 84 Re: '99 F-150 climate controls prolem [jetmech_63]
Mar 18, 2007 (9:07 pm)
I don't know if this applies but ... on my F250 the vacuum for the heater/ac vents is shared. Of all things it is shared with the auto locking 4x4 hubs.
I found this out when I was looking for information about serviceing both differentials and the transfer case.
#6 of 84 heat/ac selector switch
Apr 20, 2007 (8:00 pm)
Have the same problem as message above. Every few days I burn a breaker that controls the floor/vent/defrost selector control. It seems to be related to my backup lights also. Think it is fuse #28 under dash on 2001 f-350.
#7 of 84 Re: heat/ac selector switch [trevorwithf350]
Apr 20, 2007 (9:46 pm)
Fuse # 28 is for the Brake shift interlock, DRL Relay, Speed control Module, Vacuum pump motor, hublock solenoid, back up lights or digital transmission range sensor, heated seats, parking aid module and trailer electronic brake feed.
So, what pops the fuse?
What doesn't work?
The blower motor relay is on fuse 22 circuit.
The realy controls both the motor and the floor/panel/defrost mode.
One thing to try is to disconnect the heater blower motor resistor. The plug in is close to the blower motor.
It will run the heater motor only on high, but if the relay lasts, then the resistor is grounding.
#8 of 84 Re: heat/ac selector switch [0patience]
Apr 21, 2007 (10:12 am)
Thanks for responding. The fuse is #28 that blows. the floor/vent/defrost selector switch and the backup lights seem to be the only thing it affects. There is no rhyme or reason to when. It will be okay for a few days and then blow. So if I try the experiment above do you think this will help isolate? Is the relay and that #22 circuit connected to the backup lights also?
#9 of 84 Re: heat/ac selector switch [trevorwithf350]
Apr 21, 2007 (10:46 am)
That is the strange thing. Fuse #22 doesn't affect the back up lights. Fuse #28 does, but doesn't go to the fan circuit.
I think you may have more than just a fuse problem.
Unplugging the resistor will help to determine if it is a resistor problem, which is often a cause of the relay going.
So it is an easy test to eliminate it as the problem.
#10 of 84 Re: heat/ac selector switch [0patience]
Apr 21, 2007 (2:12 pm)
Thanks again. So if this resistor/relay is bad would it trip the #28 fuse? #22 is not blowing. You stated that #22 doesn't go to the fan circuit. I'm not sure if I made it clear that the fan speed selector is okay, but its only the floor/vent/defrost knob that defaults to defrost.