1985 F150 4.9 l6 Carb. 2wd no A/C

Have no heat. Fan works fine. Coolant is full. Bad core? should i attempt to flush it? any ideas?

 

First off, make sure the thermostat isn't stuck open and that there is even one in there. I got a car once with same prob and the t-stat wasn't in it. Put one in and had plenty of heat.

As for flushing the heater core, we tried that on one of my other cars and it worked for a short time and then it started leaking. If it's plugged up that bad, you may just be better off replacing it if it's the original one since it's not that expencive or hard to do.

 

I believe your vintage has a water contol valve. Its located in the heater hose, it is vacuum operated. Can you hear the blend door move or see the actuator operate?

 

Bill... From the sound of it, his truck should be the same setup as my 84. There is no control valve in the heater hose on mine and none of the venting in the dash is vacuum controlled. It is all cable controlled. I think the ones that had everything vacuum controlled were the models with A/C.

The only thing I thought of that I forgot to mention on my previous post is the possability of an air pocket stuck in the heating system caused from any previous work done to the cooling system.

 

Thanks Rusty for the correction. Wasn't aware of the AC as the deciding factor between vacuum controls or cable operated.

 

Rusty is right. It's all cable controlled. I've checked for air pockets. I'm going to test the thermostat later and see if its stuck.

 

Had a car with this once I couldn't get out and found an easy fix. Got the car hot so the thermostat was open, heater controls to max and went up and down a parking ramp one morning very early. Kept it in low so rpm's stayed up and on the 2d or 3d time the airlock went through.

good luck.