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Ford F-Series Climate Control

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.


  • 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.
  • Just purchased a new F150 super cab 4x4, this is the 4th I have owned.
    I very dissatisfied with the heating system, no matter what control you set it at very little to no heat will come out on the floor. Dealer removed dash replaced components and still the problem exists. They indicated all trucks on their lot acted the same way. Guess I am stuck with cold feet.
  • I totally agree with you. It takes a long time before the feet get the heat! I have the same problem with my 04' 150.
  • 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
  • fordtuf1fordtuf1 Posts: 5
    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.
  • 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.
  • 0patience0patience Oregon CoastPosts: 1,712
    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.
  • 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?
  • 0patience0patience Oregon CoastPosts: 1,712
    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.
  • 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.
  • I posted an earlier message involvig my backup lights and heat switch blowing the fuse. I have worked on my truck and discovered that these were only coincidences. #28 is still blowing ocassionally though. Can't figure out why. How could I track a ground in a wire? Where would I start?
  • 2005 F250 SD, V10 Triton. Best truck I have ever had. I have only one issue that I have taken in to the shop for and it has re-occured. When the ac is on and I put it to "max AC" it will revert to the defrost vents. And it does not blow as hard. Is it more likely to be a vaccum issue or the diverter that is not moving properly. Thanks for any advice.
  • dryfly321dryfly321 Posts: 2
    I had the same problem w/my f-350.Only defrost.The problem was vacuum oriented.It ended up being the pulse vacuum solenoid located on the pass. side wheel well.Thats where your vacuum is delivered from for the selector to work.
  • rman6rman6 Posts: 11
  • rman6rman6 Posts: 11
    has anyone else had trouble motorcraft heater cores in f150's. I had dealer replace mine last November. It went out again in December, then again in February, and finally last week. They checked for electrolosis the last two times, and tried to explain to me this morning that it still could be electrolosis. Just wanted to know if anyone else has had similar problems. The dealer said that they've checked around and I'm the only one, but how many heater cores have been replaced on 98 half tons in the last six months?
    I appreciate any feedback.
  • jddaddjddadd Posts: 1
    got in my truck today and no readout on panel. no ac. its hot in texas
  • i turn on my truck the defrosters go on high speed but everything is off, i put the ac on and defrosters stop but i have no speed on ac
  • Aside from the passenger window regulator going, which was $400.00 to replace, I have a problem with the temp control. AC never really gets cold and the heater never gets really warm. In addition, my cig. lighter doesn't work. When I try to run power (XM Radio) off the cig lighter plug I get intermittent power. Could the two be related ala electrical problem. Help.
  • 2004 F250 never got heat or ac to lower vents everything defaults to the defrost vents and no one has fixed it yet? anyone have a solution?
  • I own a f-350 2004 6.0 It just started not putting out heat even if the temp control is on high. It does this at idle. But if you drive down the freeway it will start putting out hot air and then it changes to warm air without touching the Temp switch. If you stop and idle the air turns cold. It is in the ford shop but after a day of testing they don't know what's causing it. They did say it might be the head gasket but they are not sure.
  • kj4mjkj4mj Posts: 2
    Sometimes I have heat and sometimes I do not. Had anti-freeze, thermostat replace. Did not hear hissing sound when changing to floor, froster, ect. Had that replaced too. Not sure what the issue is now. Anyone have the same issue or anything close to that.
  • Did you ever determine what the problem was.
    I have the exact same issue. Started yesterday. 2004 F250 6.0.
  • kj4mjkj4mj Posts: 2
    I had the climate control panel replaced in my truck and that seemed to help. It takes a while for heat to come out after about 30 minutes of driving now. The person working on my truck thinks it might be a motor issue under the dash that controls a panel the directs the heat( open / closes a door). He has to take the dash out so replace the heater core while he's there. It seems to me a lot of the Ford trucks have this issue, even the newer models.
  • I checked the level of coolant in my truck and nothing was there. I stopped off at the local NAPA Autoparts and poured in an entire container of antizreeeze. Still didn't register. continued to fill the reservour up with water to the lines. Started the truck and instantly the heater started working again.
    Feel pretty stupid for something as easy as coolant level. I am going to watch it though, because it's going somewhere.
  • I have a f-250 lariot. the blower motor on the a/c / heater only works on high. does anyone know what could possibly cause this?
  • is there any way to change the celicus to farenheight on the display. nothing in the manual. been searching the web so far nothing. I have an f150 lariat 2003
  • mschmalmschmal Posts: 1,757
    Anyway, I'll assume that you bought the truck used and don't have a manual.

    You can download your manual here:

    If you were to read the manual, on page 41, you would learn that if you press and hold the MAX A/C button and the Defrost button together for 1 second, it will switch you from F to C :)

    Good Luck,

  • I have a 1995 f-150 with a 4.9- 6 cyl.
    we have replaced the thermostate (with a 195(recomended),This we tested and it works.We also maded sure the water flow thu the heater core-is flowing, (we hooked a water hose to each heater line and water flowed,good),and the flapper controll under the dash is working.The 2 hearter water lines are very hot after engine runs a while.
    the heater will not get warm.
    you got any ideas we can try?
  • Check the blower motor speed control modual/relay/resister. Will be located in engine compartment attached to either the A/C coil box or the heater core box. If you have already solved the problem please let me know. I have a friend with the same problem in hers,She is not willing to spend the $90 the part costs unless it will fix the problem. [email protected]
  • rob2an2rob2an2 Posts: 1
    I have the same truck and having the same problem. Have you figured out what the problem was and how to fix?
  • y49sidesy49sides Posts: 3
    04' F250 has 54,000 miles. I first checked the colant level. It was low. (Added two gallons of 50/50 coolant in January. Just two weeks ago I check the level again and it was two gallons low.
    Took it into the Dealer. System would not hold vacuum.
    They replaced EGR Cooler, Oil Cooler, T-stat, misc. Factory Warranty. so far so good.
  • The problem is usually not the heater core, but the blend door. The F150(and Expedition/Navigator which use the same plenum box) have a common problem with the plastic axle breaking. The OEM fix requires complete removal of the dash, including removal of the steering column and evacuation and disconnection of the AC refrigerant system. It is a time consuming and expensive repair.

    Check out this web site for diagnostic information and options to repair the system at costs significantly below what the dealer will charge. These guys are the experts on blend door issues on Ford, Chevrolet, and Chrysler and have a bullet proof solution to the problem. link title
  • I am having major problems with the climate control in my truck. If its in the mid to upper 70's and I want AC I have to set the temp to 60. If I set it to 65 it blows warm air. Of course at 60 it get freezing in the cab. The same goes for heating. If I set the temp to 65 it blows hot air. The interior gets very uncomfortable. So I put to 60 and the cab gets cold. I have to keep alternating between 60 and 65. There are no in between settings. Is anyone else experiencing this problem.
  • cmms1cmms1 Posts: 14
    I took my truck in for service today with the same problem. Was told that Ford issued a service bulletin to all dealers indicating that Ford engineers were researching this problem and something will be out in late November. The local dealership advised me to wait. :sick:
  • wkeanwkean Posts: 2
    i have a 01 f350 diesel and have an issue with not being able to select either floor or vents etc defaulted to defrost, i have checked the fuse #24 for the blender door and its ok, just wondering if anyone else had any ideas what i should be looking for I don't have a shop manual for the truck. also doesn't seem to do anything when placed in ac position.

    thanks in advance Warren K :(
  • I have a 2007 F150 and I am having a problem with the climate control. It won't control the temp. I took it to a dealer and he tells me that the part I need is on back order and other dealers are wanting the same part. Is this a ford problem that others are experiencing?
  • I had a leak in my heater core. After putting in some Stop Leak the steaming up of the windows stopped but I still have the odor of Anti Freeze in the cab. I had the same problem with the odor a couple years ago in the summer and took the truck in. After 24 hours with 30 lbs of pressure on the system they told me there was no leak. So I had them change the coolant anyway and here I am. Even when the cab was steaming up I never seemed to lose any coolant yet the odor remains.

    Has anyone had a similar experience? It is a 1997 F-150 Lariat with 4.6 8Cyl.
  • My temp control problem has been resolved. It was the blender motor. See your dealer if you are still experiencing problems.
  • I've got an '03 f-150. My blower only works on high. It's really noisy. I lost low first, a few months later I lost medium. Any help would be greatly appreciated.
  • Can not turn off heat, turning manual temp control does not stop heat. Could it be a vacuum problem or is it the blend door, if it has one? Could it be that the hot water to the heater core is always on?
  • Try pulling off the temperature control knob and turn the control with a pair of pliers. On my 1999 F-150 the knob had slightly cracked where it slides over the shaft on the control, so.when I turned the knob it didn't turn the shaft.
  • Thank you for your response. Unfortunately I have already checked the knob and it is functioning properly. Hopefully it is only a vacuum leak, but, if not, it may mean the blend door is broken.
    If anybody has any other solution to check it will be greatly appreciated.
  • A common fail with the F150 is a broken blend door. Check the internet for a video and aftermarket solution for this problem.

  • mccmsmccms Posts: 1
    I have a 2000 F250 and the ac only blows from the defrost no matter where you move the settings to could this be the vacuum soleniod on the passenger side of vehicle
  • dpj1dpj1 Posts: 1
    Hey I have the exact same problem. Have you fixed this and if so how mucnh are they wanting
  • wkeanwkean Posts: 2
    yes I found the problem it was a vacum leak at the front hubs the vacumn hose had split where it attaches to the front hub. just cost a little time to locate it, :)
  • jlcjlc Posts: 30
    Hey Guys, I have an 98 F150 4.6 V 8. When I switch between outside ac to max ac or vis versa I get a musty oder. do I have a clogged drain and if so where would it be located.
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