Does anyone know if there's any way to make the air conditioning work on the other settings? I would like to be able to make mine blow cold air on either the foot setting or the foot and dash vent setting. This is for a 02' F350 crew cab.

 

The only way would be to augment the wiring in the head unit or add a relay and power it to the compressor (+). I had an 85 Celebrity I did it to because the factory wiring would break even with the updated harness back in the day.

 

The A/C compressor should already run in all settings except floor and vent.

 

I always preferred an A/C system that had a button for A/C and a separate **** for outlet selection. I can see no reason why you couldn't add a toggle switch on the dash and run power to the + side of the compressor plug to do what you want to do.

 

I do too. One of these days I'll look at the wiring diagrams and figure out how to rewire the A/C compressor to run off of a switch instead of the ****. I don't think it will be the most difficult undertaking but I don't think it would be the most difficult. I haven't looked into it yet so I could be wrong.

 

Wiring is the easy part.





The HVAC missing door may be the hurdle. Don't know what position it is in on the other settings.


Just jump the compressor from the (+) Battery and try it prior to beginning your journey.

 

This is true on my 2002 extended (Super) cab. Perhaps you have a vacuum issue where the heater door is malfunctioning?

 

These are some good ideas. I'm going to give the toggle switch a shot and see if I can't make that work. Everything on my hvac works good, I would just like my ac to blow at my feet sometimes.

 

Is there any logic in the compressor on off cycle that you would be bypassing? Or is that taken care of with pressure and temperature switches? Might you be bypassing compressor protection too?

 

I don't know where the sensors tap in to control the compressor. I know that the compressor kicks off when it gets cold (<50F?) but I don't know if that's a protective feature or not.

I was looking to tap in near the dash switch to control the compressor with a switch (button like on other vehicles) instead of the dial.

 

The positive side of the circuit goes from the cab controls on a violet wire, through the low side switch, then the high side switch and to pin 41 of the PCM. When the PCM detects voltage on pin 41, indicating that A/C is being called for and both pressure switches are closed, it sends signal voltage via pin 16 to the A/C relay in the auxiliary relay box causing it to close and power the compressor field coil. If you want to manually control the compressor, the violet wire from the cab controls would be the spot.

 

Thanks for the wiring class. That saves me a lot of schematic tracing through PDFs on my shop manual. Reps sent!

 

No problem; glad to help. I do need to clarify one thing for people who might find this thread in the future. The wiring info applies to 2002-2003 models. 1999-2001 is wired differently.

 

To reiterate what Pikachu said, the only time the A/C won't engage is Off, floor only, and floor/defrost. Defrost alone uses the A/C (it dries the air a little).

 

My A/C works in floor/defrost. The only positions mine doesn't work is OFF, dash only (not to be confused with A/C which is dash only with A/C), and floor only. I'm not sure if the pre-2002 trucks have different selections or not.