Question about 2004 Ford F150

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2004 f-150 heat control will not switch from defrost to floor

Cannot get the heat to switch from defrost to heat or dash (vise-versa) without turning off the ignition. Blower speed settings work good, lots of volumn. Truck takes a long time to warm up but stays warm (even at -30C temps). Also suspect vacuum issue as the truck has some hesitation/bucking at highway speed at steady throttle position (noticeable at 110km to 120km per hour)

Posted by cragola on


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You have a vacuum leak that is not only affecting motor operation but also the correct operation of the vacuum switch controlling your damper. Need to have that matter resolved -check all vacuum hoses and fittings for integrity/tightness. Vacuum switch itself might be leaking!

Posted on Sep 02, 2017


5 Related Answers



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SOURCE: Air conditioner blows through defrost vents


Posted on Sep 13, 2008



  • 9 Answers

SOURCE: Heater Blower on '95 Ford F-150 XL, Brrrrrrr!

could be your thermostat, thats quick and easy and cheap. could also be your water pump, not easy or cheap. could also be your heater core, also not easy or cheap. but i would start with the thermostat, chould cost you less than $10 for the part, and maybe an hour or two to do it yourself. if that doesn't help i would probably do a radiator flush, preferably a pressurized to get all the gunk our of it, and you'll probably have to go to a shop for that and cost you around $100, and they will tell you what the problem is, whether its your pump, your core, or you could even have a cracked radiator. and if thats the case, after you have it flushed get some of that radiator seal stuff, you just put it in your cool radiator(not the resevoir) and the the engine run for an hour or so. not a permanant fix, but this could all get you a little extra warmth.

Posted on Dec 23, 2008

Hayward Cowan

  • 58 Answers

SOURCE: my truck will miss and hesitate at highway speeds

Check your fuel filters, many Fords have 2 the second one is mounted on the frame and takes a cartridge.

Posted on Jan 12, 2009

Bruce Hathcock

  • 3600 Answers

SOURCE: Control knobs on the dash do not change the route of the air from the defroster, it stays coming through there and cannot be sent to the console vents or the floor vents.

Yes vachum controls all the doors on it go to and buy a subscrption there for your car they will have all the parts location for you there, most likely the blend door vac. motor is bad.

Posted on May 28, 2009

Mark Babineau

  • 1129 Answers

SOURCE: what would cause my '02 Camry to hesitate, buck,

Even though there is no check engine light I would still take it to Auto Zone to see if there are any stored codes.

Posted on Jul 16, 2009

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Sorry for your troubles ,
Temperature Hand in dash reading NORMAL ?
Does it Turn Blue to Red if so is do you feel friction or restraint like your turning something rather than freewheeling (smooth fast turning) or Digital and or does it show that it should be warm and not cold ?
Does the TEMP change at all(even the least little bit could narrow the results down) when knob is turned?
POSSIBLE - The Actuator/Motor that switches the VENTS very well could be BAD , Temperature Switch / Climate Control Switch (hot to cold could be broke at the base and only allowing the knob to turn and not in the switch ) Thermostat may be stuck open (keeping the engine running cool and smooth but no heat , maybe just a slight TEMP change when switched from Cold to Hot ). The A/C Switch is pushed in or turned on or broke and is stuck ON
FIXES - 1st- Check FUSES - If Temp HAND Reads Normal it not your THERMOSTAT. - Change the Control Switch / Temp switch - Check A/C Button/Knob . AUTOZONE is my place of business they PRICE MATCH AS WELL!
Hope this Helps , Flaming Ratchets Auto Repair

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1996 Montero Heater Blower not working

I assume your heater setting is electric control, if so either your defrost and floor heat switch failed or wire problem. For the air not hot, check the heat control valve on the top of the hose it should be in front of the firewall. I don't know your car is using mechanic valve or electric control valve. Anyway check there first. Good luck.

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Climate Control - Heat and cool work fine. Air flow is directed to defrost /floor. No indication (Sound or sight) that the vacuum diaphrams are being activated. The display on the dash matches the...

Does your vehicle have manual or automatic climate control ? You system is stuck in floor an defrost mode ?

03 mercury grand marquis hvac air flow .-13qahwfdndst2y1hypmr2cdq-4-0.gif Item Part Number Description 1 18A318 Vacuum control motor-floor/defrost door 2 - Defrost air flow 3 18A478 Floor/defrost door 4 18476 Heater core 5 19860 Evaporator core 6 19805 Blower motor 7 - Outside air inlet 8 19A813 Air inlet door 9 18A318 Vacuum control motor-air inlet door 10 - Recirculated air inlet 11 18B545 Temperature blend door 12 18A559 Panel door 13 - Panel air flow 14 18A318 Vacuum control motor-panel door 15 - Floor air flow 16 - Vacuum from the engine intake manifold 17 19A563 A/C vacuum check valve 18 19A566 Vacuum reservoir tank and bracket 19 19980 EATC control
Pull the control panel an check for vacuum

vacuum lines hvac 03 grand marquis-13qahwfdndst2y1hypmr2cdq-4-2.gif Item Part Number Description 1 White Air inlet door 2 Yellow Floor/defrost door 3 Red Floor door 4 Blue Panel door 5 Black Source vacuum 6 - Not used

VACUUM APPLICATIONS CHART-ELECTRONIC AUTOMATIC TEMPERATURE CONTROL Switch Port Vacuum Harness Hose Color Func- tion Manual Override Selector Buttons OFF MAX A/C NORM A/C VENT FLOOR FLOOR/ DEF DEF 1 White Air inlet 2 Yellow Floor/ panel (partial) 3 Red Full floor 4 Blue Panel 5 Black

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Control knobs on the dash do not change the route of the air from the defroster, it stays coming through there and cannot be sent to the console vents or the floor vents.

Yes vachum controls all the doors on it go to and buy a subscrption there for your car they will have all the parts location for you there, most likely the blend door vac. motor is bad.

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