Hello, I've been having some problems with my F-150's heater. First I noticed that I don't have a windshield defroster any more. Then I started smelling antifreeze in the air. Well, I figured I should be able to fix all of this, after all, heater cores and actuators are easy to replace once you pull the dash cap, the glove box, and the stereo.

Well, the heater core wasn't too bad and it only cost me about $50 for a replacement. But when I started looking into the defrost, I found out that the actuator is working, in fact, all of them are. I just don't have air flow to anything but the dash vents.

So, how far do I have to tear it down to remove the heater ducting, and once I remove it, is the diverter something that can be fixed? Or am I going to have to raid the junk yard for a replacement piece?

Any help would be appreciated.

 

Likely a vacuum problem in the control system inside the dash. normally the 'default' configuration is to the defrost-vents when there is a problem. there is a vac-motor that controls the air direction within the plenum. that motor either sends the air flow to the dash registers or lets it pass downstream to the floor/defrost motor control vents. the panel door vac motor has a blue hose to it from the function control selector. the downstream 2-circuit vac motor has a red and a yellow vac hose to control each vac circuit in that motor. there is also a white vac hose to the outside air control motor. first thing to check is the vac check valve on the firewall in the engine compartment to make sure vacuum is reaching the function control panel.
Check for vac from the check valve to the vacuum manifold behind the function control. There is always vac to that control. The blue hose from the function controller should not have vac when the selector is in defrost/floor. If there is no vac at the blue hose then I'd say the panel door is jammed. Find the vac motor in the blue hose circuit and the panel door has a vac line attached.
Here are some excellent pictures of the heater, click on the thread. http://www.ford-trucks.com/forums/10...cs-needed.html

 

Ok, I saw the two vacuum actuators and the temperature regulator and they all have full range of motion. The one actuator is approximately behind the stereo and it moves when I switch it from floor to mix to defrost. The other actuator is behind the glove box and moves between AC, vent, and heater. Is there a 3rd actuator? (Besides the cable to the temperature regulator.)

I suspect that the flapper that is supposed to be attached to the one behind the stereo is broken or no longer attached. How much of the dash to I have to pull out to get to that piece?

 

When these trucks were new, failure of the vacuum switch was very common. Also a better ground for the blower motor speeds it up.