Help me fix my heater....
- Thread starter 84blkstang
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Ford_Racing
New Member
ok here is the deal, the lines leaving the heatercore are plenty warm, same as the radiator hoses. When i turn it on vent i can watch the door open and air will start to come through, The first about 20 seconds will be warm, not hot like it should be. Then it goes to cold. I checked all the vaccume lines also. It is weird because it will blow cold, but if i put it on warm then it doesnt blow hardly at all so does this mean the temp door inside the heater box? I really need some help here i have driving dressed like an eskimo
I'd take the car to your local chain repair shop like Tuffy's or whatever, and just pay the 50 bucks to have them tell you what's wrong with it.. then fix it yourself 
a few bucks might be worth the hassle of wearing a parka while you drive!
Edit: Of course you could always buy a portable 12v auxillary heater and use that until you fix the problem.
a few bucks might be worth the hassle of wearing a parka while you drive!Edit: Of course you could always buy a portable 12v auxillary heater and use that until you fix the problem.
I am broke as hell because of Christmas, i know wearing the parka sucks but i think that i am going to tear it out thursday, and take the whole thing apart. I am open for any suggestions on what it could be
Ford_Racing
New Member
I fixed mine yesterday by back flushing the heater core. I first noticed that my heater hose going in to the fire wall was hot but the return hose was cool. Bingo, we have a problem. I disconnected both and flushed water back and forth in both directions, hooked it back up and now I have heat.
Hi, all! I just got through reading this whole post and it sounds like a real universal problem (well, if you don't have heat, it is). First thing, make sure your hoses to the core are connected to the proper core connectors. Most 5.0's came with a restrictor to limit flow in the inlet hose leading to the core so the high rpm's don't blow the seams. If the hoses are backwards... limited flow. Remember the radiator gets priority flow over the heater core as soon as the t'stat opens. Secondly, if the core has outstanding flow when you backwash it with your garden hose, it's probably flowing well enough to heat your interior. In that case, you must make absolutely sure your cooling system is full. Jack up the side of the car that your cap is on to make it the highest point in the system. Right now, the heater core inlet hoses happen to be highest (on level ground). Run the car about 1500 rpm until the t'stat opens and fill the system until all the air is out. Cap it (Make sure it's the right cap). Let it down. Make sure there is A/F in your overflow bottle and the hose is not plugged. If all these are ok, you should have and maintain at least some heat. I'll come back later with the vacuum and door and cable stuff.
Here's the address for the plenum by the various settings.
http://home.stny.rr.com/bomansinusa/Mustang Plenum/mustangplenum.JPG
http://home.stny.rr.com/bomansinusa/Mustang Plenum/mustangplenum.JPG
The Temperature blend door is the one that is cable controlled by the TEMP knob on your control panel. It moves to block or allow airflow through the heater core. The cable is self adjusting, however, make sure it is not kinked or out of adjustment as this will result in a little or no heat condition! To adjust: Start with the cable clip about 1" from the 'loop' end of the cable. Install on the blend door lever and turn your temp knob slowly but firmly all the way to max. heat. It should now be adjusted.
ECU5.0
Banned
ive checked everything, both lines to the heater core are hot...well warm, they dont get that hot. im thinkin it might be because of that restrictor that is in there. blend doors are working properly and everything else seems to be working correctly also. what gives?
ECU5.0
Banned
the heater core is just over a year old and was brand new when i put it in. the coolant is clean and i have no buildup anywhere. i cant figure this crap out. guess ill just wear a jacket
Ford_Racing
New Member
JB66 said:
People, please recheck the position of the plenum doors. If nothing else, pull the 4 hoses off the door motors, disconnect the blend door and try it! You will get all the heat you're going to get from the core directed to the defrosters. Move the blend door and see what happens! With the blend door to full heat, if you're hot at first and then get cooler and cooler, you probably need a heater core!
for the diagram... 'P' is partial Vacuum; 'V' is full vacuum
well i took the cable off and it wasnt kinked or binded, so i operated it manually and it still wasnt warm... so i dread i am going to have to pull this fn box out of the dash again..... any other ideas? What i dont understand is why it doesnt blow warm but everything works when cold, this has to be the heater door right?
vikingpower
New Member
check the restrictor valve, I read in one of my 5.0 books that the restrictor valve thing can get turned around in the heater hose, restricting flow, and it recommended to put a clamp around the hose where the restrictor is to keep it from moving around.
rd
Founding Member
It would appear that the temp control door is stuck in the wrong place, or something similar. I do not remember exactly,off the top of my head, but there are at least three control doors in there. I think all the air from both inside and outside goes throught the ac evap. In ac, there is a door that closes off the path to the heater core, operated by the temp control cable, (on my 79 Capri, anyway). Raising the temp setting opens this door and diverts more and more air through the heater core.
The doors that divert air to the panel, heater and defroster, and the recirc (max air) door are the vacuum ones.
I think you can see the temp control cable connection at the door, and can check it for movement. Later cars may use vacuum for this also, not sure.
The doors that divert air to the panel, heater and defroster, and the recirc (max air) door are the vacuum ones.
I think you can see the temp control cable connection at the door, and can check it for movement. Later cars may use vacuum for this also, not sure.
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