is it normal for the freon compressor to run when the heat is on on my 2001 F150 Lariat?

 

Yup.

 

ok then, would it help my gas milage to disconnect it through the winter? Or does it serve some use?

 

It is used to dry out the air when defrosting the windows. Without the compressor, you'd just blow humid, moist air on the wet windows. The AC will remove the watervapor from the blowing air.
You can install a small switch that turns the AC on and off. It's pretty simple and only requires working with two wires.

Fritz

 

ok, now that makes sence. I see in a print i have there is a wire from the Function Selector Switch that runs to the AC pressure cutoff switch. Is this the wire i should use to cut the system on on off? I am useing a Haynes Repair book as reference. Page 12-34

 

Remember, your windows may stay fogged up more than before.

 

There are two wires involved.
The PPL (Purple) wire from the Function Selector Switch to the AC Press Cutoff Relay and the LT BLU/PNK (light Blue with Pink stripe) from Fuse #5 to the Function Selector Switch.

-Splice into the LtBlue/Pnk wire. One of those clip on splices works fine. Get the smallest size. Run the splice wire to the switch.
-Cut the PPL wire. Tape up the wire sticking out from the Func Sel Sw. The other end of the PPL wire from the harness goes to the switch.
-Wire in a switch between the LtBlue/Pnk splice and PPL wire.
-Turn on switch, AC compressor comes on.

I recommend a 12v LED wired to the AC Press switch side of the PPL wire switch to let you know if the AC is on. Radio Shack makes a red/green/yellow 12v LED with holder that works very well.

On my truck I installed the switch and LED inside the AC control box for a factory look.

Fritz