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FORD mechanics...

Jacob2008
Alright. We have a 94 ford F150 300 6cyl. It wasn't blowing heat, so we changed the thermostat. It was stuck open, got it all done, flushed it, and put new antifreeze in it...

It still isn't putting out heat, any ideas? Maybe its the sensor thats right there, but not sure.

ANY help appreciated.
Thanks
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Comments

31 comments

Date Votes
  • bhale187
    could be heatercore
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  • badcompany
    it has nothing to do with the thermostat. does the thing blow any air ? if not then its the blower motor. if it blows cold air but not hot air then its the heather core. a simple check to see how much amperage the blower motor draws when you turn it on will tell you.
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  • Jacob2008
    blower motor blows, heater core doesn't leak. It had SOMETHING to do with thermostat, it was stuck open, it blows a little warmer now but not at all very warm
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  • Jacob2008
    quote:Originally posted by Flying Clay Disk
    What temp thermostat did you put back in it?
    192. its same as the stock one it came with

    temp gauge works now, but it still isnt blowing warm
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  • Cubslover
    quote:Originally posted by Flying Clay Disk
    What temp thermostat did you put back in it?



    That was my question.
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  • savage170
    could be vacuum line off at control valve
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  • fishkiller41
    Make sure the "flow valve" is opening Jacob. If not look for vacuum leak.If it's cable actuated, U may need to lube/replace the cable.
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  • Jacob2008
    Can ya take the heater cores out and put a garden hose in it and wash it out? [:D][}:)][}:)]
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  • savage170
    Just take heater hoses off at heater core put garden hose on top inlet
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  • fishkiller41
    U could , but it's a MAJOR PITA! U can take the hoses loose under the hood,and blow air/water through it BACKWARDS. Opposite normal flow.
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  • Jacob2008
    we'll go try it [:D][:D]
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  • fishkiller41
    quote:Originally posted by Jacob2008
    we'll go try it [:D][:D]
    Let us know, what U find...[;)]
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  • slipgate
    Almost for sure it is the heater control valve which is vaccum operated - this is what lets water run through the heater core.

    It is highly doubtful that it is the core and it is NOT the engine thermostat, that has absolutely nothing to do with the heater.

    It also could be your climate control "blending" doors that mix hot/cold. Try going to both extremes, if these are electronic, that is most likely your culprite.
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  • frog21
    If heater core is plugged up,it will cause your no heat problem.Heater cores are easy to change in ford trucks.Shouldn't take more than an hour to do.
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  • Captplaid
    I had a 91 F150 with the 300. Same problem. Changed the themastat once cause I thought it was stuck open. The gauge also ran a little colder than I thought it should. Thermostat did not help. Gauge still showed it to run a little cold and heater was not better. Eventually, that thermostat stuck closed. No change with the third one. I suspected it was either a cold running engine or over capacity radiator. I never tried cardboard over the radiator.
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  • catpealer111
    My experience with the 300 is they take a while to get all of the air worked out of the cooling system. Recheck and top off your antifreeze level once a day for about a week and you should get your heat back. It also could be a bad thermostat again. I know you just put a new one in but I've seen new parts go bad before.
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  • Captplaid
    that was one bulletproof motor. I ran it hot and so low on oil that when I stepped on the gas, the oil pressure dropped. Neither hurt the motor.
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  • fishkiller41
    I bought one out of a "retired" UPS truck.( Ford 300 CID ) And put in a panel-truck. It had about 175,000 on it ,when i got it. Put new T-Chain,W-pump,Lifters, and had the valves ground. I still see it running around here, once in a wile. Oh,, i put at least another 150,000 before sellin the truck.That's 325,000, when i sold it 6-7 YEARS AGO!!

    Damn-good engine, TONS of lo-end torque too.
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  • SCorvers
    Flow control door.
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  • LesWVa
    Before you go ripping out the heater core and hoses.

    Do a few simple checks first.

    1. Check along the inlet side of the heater hose for an inline valve that may have a cable or vacuum hose connected to it. If you locate one. Check that it is opening when the control in set to hot. If not open it by hand and check for heat.

    2. Under the dash. If it uses a steel cable to control the temp. Make sure that it has not kinked or came loose. Does this 99% of the time where it connects to the heater core. People never take the time to clean and lube these cables.

    3. If it has a Vacuum hose to control the heat. Pull it loose from the vacuum chamber next to the heater core. Check for vacuum at the end of the hose when the temp is set.

    If you find a problem with one of the above. repair it first before ripping the heater core out of the truck.
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  • Colt Super
    I have an '83 F-150 with the 300 c.i./6, and it has always had the problem you describe. Just takes quite awhile to get the cab warm.

    Doug
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  • 1911a1-fan
    actually heater core in that thing is a breeze, 6 screws right under the glove compartment

    if all of the above does not tell you something it may not be shutting the door and leave the vent open, it happens allot on similar years, take the temp control, move it back and forth quickly on the last try slam it all the way to hot, ive been through that exact system 3 times over the years, i have a 92 e150 right now
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  • 11BravoCrunchie
    Heater core plugged up. New heater core.
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  • tccox
    Does the defroster blow hot air?? Tom
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  • Captplaid
    cardboard over the radiator.
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  • gjshaw
    If the flow control is opening then you have air in the heater core. Just like your old house rediators that had to be bled for them to put out heat, your heater core has air in it and till you bleed the air out by taking off the return hose for the heater core you will never get heat out of it. Start the truck and loosen the return hose and let the air out till it runs all liquid. Then refill the radiator to proper level. Have seen this happen hundreds of times when changing the thermostat and getting air in the system. Air goes to the highest point in the system and will stay there till it has a place to excape to. It is almost like bleeding the brakes with air in them to make them work.
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  • jltrent
    Could be the radiator cap bad and not letting it build up proper pressurer. Long shot could be blown head gasket. Does it maintain liquid level?
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  • Mossbergboogie
    Well have you tryed compressed air yet. Put an air hose on the in flow tube and give it a shot of air. If you get heat problem solved if not put in a new core.
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  • 180A
    Some Fords have an ambient temperature sensor/sun load sensor in the dash. Had an old Towncar heater that wouldn't put out much heat -- the sensor was bad.
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  • cowdoc
    I had a 92 f250 same problem.....was cable from temp control switch in dash down to where it changed the position of mixing door that allowed you to control the temp kinda a b i t c h to change....you can reach under there and close it by hand to see for sure if its your problem
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