Heater A/C question???

[VanceH]

Ok, i have tore my heater box apart to clean it up a bit and see if i can make it work, found a short in the fan switch so now i have low and med (no High???) but i cant seem to get the air to the defrost, it only comes out of the A/C ducts??? I was looking at LMC and the diagram shows #11 as the control box any ideas on what is up??? Also what diaphram under the hood stops the hot air from blowing all the time?? I have two one close to the fire wall and one looks like the A/C hose?

[red71cheyenne]

Up inside the "S"-curve piece is a flapper. Ok, not the S part, the part it connects to, with the 2 outlets on it, that go to the defroster hoses. That is what redirects the air from A/C ducts to defrost. This is on A/C equipped trucks. If that flapper is stuck, you won't get air out of the defrost. Reach up in there and try to move it real easy. Cable for it may be rusted up. IIRC, there may be another one in the 3 outlet box as well that redirects as well and they move together when selecting defrost.

[Hottrucks]

if you reach under the pass side near the hump you will see/feel the cable there if the cable is moving the lever than the flapper is broken of the arm...from what I have found this is a common problem...I have the same issue and it must be fixed from the inside of box #11 I have to do it so keep me posted but it looks like not to big a project just time comsuming......I cleaned mine box by splitting the AC box on the fire wall......

now your fan issue is in a relay located against the A pillar side of the cab behind the glove box to the right of #11 box , you should see the wire harness going over the box into it..the part is about $10 at autozone and take 15 min to change....the relay is bolted into box !! kinda a pian to get to ....

[VanceH]

There is nothing in the s curve piece??? What number on the chart above?

thanks

[red71cheyenne]

Sorry, had to edit, I'm dumb. The first one is the part with no number and its whited out.

[red71cheyenne]

The other one is inside number 11.

[Thealien]

I just had the same problem, here is where I bought my diverter box, I think they had another one


WHERE I BOUGHT MINE

And here is a
THREAD I STARTED WITH THE SAME PROBLEM

There are some pics showing the box, and the resistor.

[Thealien]

BTW I repaired the flapper door in my diverter box with some epoxy and it is holding up well for a month. When you take the diverter box out you can look inside and see where the flapper is broken away from the shaft. I epoxied it where it would not interfere with anything. I put it on kind of thisck and went up the sides so the repair is kind of L shaped up each side on both sides of the door. What have you got to lose?

[Lugnut64052]

Yeah, #11 is where the flapper is. The common problem is that the flapper breaks at the hinge, so even if the lever is working it's still not moving the flapper door back and forth. It never breaks bad enough to fall out or anything, it just sits there dead, and the lever doesn't move it. You might try epoxying it. I tried fixing one but it didn't work. My guess is you'll have to go for a new one.


The hot and cold is controlled by a cable actuated door in the evaporator case. It's the lever in the red circle . . .





When it's set like this, you'll have heat . . .





When it's set like this, you'll have cold . . .

[old man jimmy]

yep, common problem. I've replaced several on mine through the years. Finally came up with why they break. If the door is hanging horizontally and you hit a chuck hole or big bump, it snaps off from it's own weight. What I started doing when I got off road. I'd move my dash control so the door was vertical. Sorry, but it's been so long I don't remember to what setting on the controls. But if anybody has a box apart, they can see what setting, and maybe post it so all will know. And it's not that the plastic gets old and brittle. New ones break just as fast as old ones.

[VanceH]

lugnut is that switch on the outside of the firewall or under the dash??? what controles it??

Thanks
vance

[Hottrucks]

thanx great pics Lugnut
his pics you are looking at it from the fire wall out toward the front bumper..the lever is almost in line with the pass wiper next to the hindge under the hood

[VanceH]

Ok cool i found that one, when i am parked i get nothing thru the heater unless i turn the fan on, but when i am driving i get hot air thru the ac ducts?? i cant seem to stop it at all. Some one said something about the vacuume line that is in the heater hose?? what does it really do?

thanks again for all the great help

vance

[VanceH]

ok found another diagram, PROPS TO LMC!!!! What is the heater resistor? #5

[Hottrucks]

that is what controls the low and med. on your fan like I said I think your issue is on the inside to the left of box #11 that is where the HIGH speed relay is for your fan.....if you split your AC box ( I pulled the engine side off) you can get int to clean out the "stuff" in there and the area around the area Lugnut posted pics of you will alos see the resistor in question..it was and easy oon easy off place to get inside and vacum out

[Thealien]

There is a picture with that resistor in it in the link I posted. It is in the right hand corner looking through the glove box

[VanceH]

sweet as soon as i get back home i will tear into it and see what i can do, thanks for all the help