1984 ford f-150 the heater is blowing out the vents , and will not blow on the floor or the defrost settings, there are two vaccum modules on the heater outer case one stands upright and I can tell that when I select the floor or defost it moves up or down. I don't know what the other one does. What might be my problem with the controls?

 

They are operated by vaccum...try to disconnect one that isn't working while the heater is on defrost, it should move in, although all it does is let hot antifreeze into the heater core, it should still work. You could have a blockage at your doors insiide the vents where the heater core is, Its under the pass. side where the Heater Blower motor is. Is The a Van? Truck? Am thinking it could be a cable system...but am not sure, if it is....the cable could be loose around the small 1/4 screw, you'll have to check it to be sure its working. Its under the dash near the pass side close to the middle area, easy to get to.

 

Its a truck, and the only manual part of the selector is the one that adjusts the temp.

 

Your problem may be the heater duct door itself. I have an 84 F-250 and had the same problem. Bottom line is all the controls can be working fine but the door that the vaccum is connected too only has a plastic pliable "hinge" That is to say, its a piece of plastic that bends, not an actual honest to goodness hinge. They wear out and break so that the door just flops around until it gets caught cockeyed and then it does nothing. When I figured mine out I was in Arizona, where 80-90 Fords are easy to find. The problem is this problem was so common Iwould go throgh truck after truck until I finally found one this hinge was still intact on. Itwas a pain because to inspect the door you have to disassemble the passenger side dash to get too it. Hope this helps.

 

when the door is open, and you'll have it on heat. to check it....you'll have to remove the heater blower motor to see what it is doing, or if there is debre or leaves, small sticks lodging the door close. there is about 8 screws holding it in, they are 3/8 in. Use a nut driver to take them loose and set aside the motor, (some have a disconnect on em and others don't. get a flash light and inspect it.

 

leon45 I just fixed the hinge Queben is talking about on my 85, stupid plastic thing, and you do half to take apart half of the dash good luck.

 

I had the same problem. I checked the Ford dealer, they could get the part for $23.00. I thought I would try the local home improvement store, got some $2.00 hobby hinges (metal), drilled a few holes, shot a few screws, not it works as good as new, and I don't have to worry about that problem again.

You do have to take the dash apart to get to it, but it really wasn't as bad as I thought it was going to be.

rick

 

Ford Dash are easy for me...used to stripp the interiors before the big Hyd Crusher made pancakes out of em....they were'nt all that hard...found a lot of pencils, pens, loose change, a few dollar bills and leaves, an sticks-you get the idea, lots of small stuff can get in there and block the vent door through the defrost vents. and its worth taking it apart, who knows you might even find a diamond ring like me.....

 

I just did the piano hinge thing this weekend after reading the above helpful posts. Yes, it took a bit of work, but I'm appreciating the defroster and floor heat now!

I do have a question about the max/norm A/C setting. If what I saw after I pulled the blower motor is correct (hoping the problem was there), in "Norm" and all other settings except "Max", the air coming into the cab is drawn in from outside--whether for A/C or heat functions. On "Max A/C" the intake air comes from inside the cab.

Why draw in cold air to heat or defrost? Why not recirculate from inside the cab? Or is there a concern that there would be too much moisture in the cab already and the fresh air would be drier?

Thanks for the help!

 

I am so glad you guys posted this. I have been dealing with this problem for a long time. I will have to look at my door too. My question is where is this door. I havent disassembled my dash yet(and really dont want to) Do you like, take the glove box out and dash pad, ect. ect? Sounds painfull for someone who has never taken a ford truck dash apart.

 

You'll be suprise of how quick the windshield defrosts with the setting on cold air and the other setting on defrost.....the newer autos have this mixture already built into the system. This is only when the inside is "frosted" over an you can wipe your hand to see the moisture....for those icely-snowly windshields...use warm air defrost...so you don't crack your windshield.

 

Yeah, it's a chore.

Start with pulling the glovebox liner--shouldn't need to remove the glovebox door, but may have to remove the strike plate (where the door latches) to get the liner out.

Then look for the vacuum motor/actuator--just a little to the left of the left edge of the glovebox opening but about 6" back. Start the engine and move the vent lever to see if the vacuum motor is doing what it is supposed to do--going in and out. If that is fine, then it is likely all it is doing is wiggling the door around--but with no hinge around which to pivot, it's not doing much.

Take the dash pad off--4 screws in the defroster vents, 4 or 5 along the front edge of the dash. NOT all of the screws above the glove box need to come out--at least at this time. Pull the dash pad off and you can see the vent plenum. There are two screws holding that to the front of the dash.

I couldn't get the plenum out without loosening the entire passenger side of the dashboard. One screw up by the far right corner of the windshield, one on the right side--accessed through the glove box, and one each above the passenger's left foot and the driver's right foot.

With the plenum removed you can see where the door should be operating. I also removed the heater core cover so I could hold the door in place while I worked on removing the jamb side of the old hinge and installing the new.

While I was in there, I also pulled the defrost and heater ducts off and cleaned them, and vacuumed out all the dust I could reach behind the dash. Test the operation of the vacuum motor that is used for the floor/mix/defrost settings. I also vacuumed around the heater and A/C cores.

I'm sure others will chime in with their advice as well...

 

To figure out what the problem was, I removed the glove box liner, and the heater core cover. If you get a light, and look in the opening that the heater cover meets up with the heat plenum, you can see the door.

I was able to determine my vacuum motor was working by simply listening carefully when I switched the lever from vent to heat. (Keep the motor running so you will have vacuum.... this is from personal, almost embarrasing experience )

You can also watch the door as you move the lever back and forth and see what it does. Last winter, I just reached my hand in there and manually set the door so the air blew through the floor or dash.

That worked great, until I accidentally moved the lever to vent. It would move the door to blow out of the front vents, but wouldn't move it back. This fall, I decided I was going to fix it permanently.

Back to the subject, I was like you, I sure didn't want to disassemble the entire dash. It was surprisingly painless, maybe not painless, but much less painfull than I expected. Just follow Rmartens' step by step. He is dead on. That's exactly what i had to do.

I pulled the upper plenums out to gain access, and cleaned them up inside and out as I did it. To get the old hinge off, I had to drill out a couple of rivets, and remove a couple of screws. To put it back in, I just used a couple of small nuts and bolts.

It took me about half a day to do it, but I could probably do it in a couple of hours. I didn't have the benefit of someone telling me about the 2 bolts on the passnger side. Once I found them, and got them out, it was a piece of cake.

Good luck!
Rick

 

Thanks. I'm going to try this this weekend or next. Doesn't sound too bad.