I recently purchased a 1996 F150 from a dealer. Of course after I paid for the truck, I learned the heater would not blow hot hair, just luke warm. I contacted the salesman and he called the previous owner. The previous owner said on the passenger side of the engine, he would unplug something that made the heater work, but then the AC would not blow cold. He did not fix the problem, but instead would plug in the sensor during hot weather for the AC, and unplug during winter for heat. Any ideas what sensor this is and where it is located?

 

The vacuum line to the diaphragm above the blower motor ???

 

I think I know what line your talking about, but I don't think the lines are for vacuum for a heater. I don't think the heater has vaccum. Is it a T-valve? I think that goes into the MAP sensor, nothing to do with heater. If your heater isn't blowing hot air, then you need to replace the thermostat, and probably the fluid. When you do that, make sure you have the heater on.

 

Just going off my '93- there's a vacuum-driven motor that appears to redirect air across either the heater core or A/C. Everything else in that area is electrical and connects to the A/C system. I'm sure several things changed between '93 & '96 though.

Neal

 

Nomo: I noticed on the driver's side of the core, there is a vacuum line, below MAP sensor, and up in the corner of the passengers wall, there is a white line to the damper door. Suppose he's talking about the door?

 

That's what I was wondering. On my '93, it's on top of the core.

However, after re-reading Stevo's post, it seems that the connector in question may be electrical. I've got about 5 plugs going to various A/C components- what about your '96?

Neal

 

I dug out the Haynes manual and checked it against my truck. My bet is the previous owner unhooked the "Clutch cycling pressure switch". It has a purple wire and a black/yellow stripe wire going to it.

The same thing can be done by unplugging the compressor. However, I'd recommend fixing the pressure switch if that's really the problem.

Neal

 

If you take it off, it'll leak fluid. Been there done that! Need to have a liceansed person do the change