Just starting cool wet weather in newly acquired '69 F-100.
The defrosting is marginal even though we have heat and fan. The dash cover, possibly replaced, has mesh over the radio speaker and what appear to be the 2 defrost vents.

Questions-
Was the original dash cover plastic or leather?
Should the mesh be there since it seems to be drastically restricting air flow?
Have other owners found improvements that help with defrost?

Thanks in advance.
Richard

 

Richard,
First question: are you getting sufficient air flow from the defrost vents (but it's not warm enough), or is the airflow from the vents insufficient. Do you get sufficient air flow when you put the heater on the floor vents? If so, the mesh is probably the culprit (or a clogged vent hose or cowl. See no. 1, 2, and 3 below). The dash pads in both my 68 and 72 F100s were vinyl, and there was no mesh over the two defrost vents. The big thing in the middle of the dash is a speaker. The two vents have about 8 little metal "fins" which run parrallel to each other, and from the front to back. These diffuse the air-flow over the windshield. Mesh over the vents would decrease air flow. In no particular order, check the following things. The heat in both my F100s has never been great.
LOW AIRFLOW:
1. Make sure that you are getting air-flow from both defrost vents.
Sometimes the hose (from heater box to the dash) fall off, or get
clogged with mouse-house stuff. My "new" 72 is still spitting a little seat padding from a mouse who decided to build their home inside one of these heater vent hoses. If a critter built there home in your heater box (near the fan) you will also have decrease air flow.
2. Make sure the fresh-air vent (on the passanger's side. Near the kick panel. It has a little plastic lever which is open at the 9 o'clock position and closed at the 6 o'clock position) is closed.
This forces air into the heater core.
3. Make sure that your cowl vent (outside the truck, at the base of the windshield) is not clogged with dead leaves, mother in law, etc.
AIRFLOW IS GOOD, BUT AIR IS NOT WARM:
4. Flush your cooling system, making sure to run some water thru the heater hoses to flush the heater core. You have a thermostat, right? If the heat gague on the dash doesn't move much, you might not have one (or it might be stuck open). Change to a 195 degree thermostat. I swapped my 180 deg. 'stat to a 195 deg. last fall. It made a small difference. Make sure your cooling system is full.
5. Make sure your heater controls are working. Ensure that the heat-control (warm-to-cool) is fully moving the heater control valve
(which should be spliced into one of your heater hoses, near the heater core). Look under the hood. Sometimes the cable slips and the control valve doesn't open fully.

That's about all I can think of right now. Let us know if this helps.

Ohio Bill

 

Thanks Bill,
Upon acquisition, a couple weeks ago, I flushed radiator and put in a 195 Thermostat where there was NONE. I freed up the heater control valve and lubed with white lithium. Heater warms the cab nicely. I think the driver side vent is open and will close that.( It was fairly warm but extremely humid when I tried the defrost to clear windshield.

I believe I'm just not getting the airflow or it is poorly directed from defrost vents. I will check for mouse houses in the tubes. I did not want to cut out the mesh if that was a normal feature of the dash pad. Will do some more investigation.

Thanks

 

Your cables may need to be adjusted. Look at the heater box, the cable to the right, take off at the heater box (one screw then push it off the arm). Manually move the lever down. If your blower is okay, you should have a hurricane force air stream.

I had nothing (especially since the heater core was not hooked up). I changed the core (was 30+ years old - probably worked though ). I cleaned out the vents inside the fender, lubed everything, adjusted the cables, and now have almost hurricane force defrost.

 

Remove the right side vent housing from the kick panel and you might find a couple of pounds of mulch that has accumulated over the years. It will not only create a restriction, but it will also work its way to the heater core and block airflow there.

Joe

 

>Should the mesh be there since it seems to be drastically
>restricting air flow?


Richard, I don't think that mesh is helping you any. The stock heater vents have metal louvers on top of the dash to direct the airflow.

Barry

 

 

Definately clean all leaves etc. from every part you can. I pulled my whole heater assembly out, lubed up the cables, dug about 5 pounds of leaves out of the pass. side vent and the side of the cab where it flows from and had it all back in place in less than 2 hours. I shudder to even think of doing that on a new truck! One thing i noticed on mine was the metal flap that deflects the air between heat and defrost was bent so the floor was getting the bulk of the flow even on defrost setting. Don't know if this is stock but I bent the flap the opposite way to remedy this and it helped quite a bit. The flap fits kinda loose so there is still some flow on the floor too. I may consider throwing an extra heater of some kind in the rear of my crewcab, have to see how she is this winter. Hope this helps a bit.

 

Thanks for the defrost info,

I will be taking it aprt this next weekend to try and get good airflow.
?Does your truck have mesh over the dash defrost openings?

Right now I am trying to stop a remanufactured carb from hesitating and backfiring.

Richard

 

No mesh just fins.