'97, V6, 50K miles, Reg Cab, Reg Bed

AC comes on not only at MAX and NORM, but also at FLOOR, PANEL, etc.

How can I troubleshoot this? Where do I start?
Thanks.

 

Two quick possibles are blend door motor, and the switch. I have seen it be both. Easiest check is to remove the little black cover on the tranny hump in nthe center of the floor on the bottom. Look to the right side for about a 4x4 square box mounted to the bottom of the air box. Thats your blend door motor. It is a common failure. Its kinda a bitch to remove, but once you get it off you'll figure out how to easily reinstall it. Bout $50 at ford I think.

 

A/C comes on, as in it's blowing cold air when it shouldn't, or as in the compressor runs in those positions? If it's the latter, don't worry about it, it's running to de-humidify the air. Normal operation.

 

I will check it.

I think it is the latter. When I set the selection **** to PANEL or FLOOR was a warm day. The air coming out of the vent was cooler than I expected. So switched to MAX (cooling) and the air temperature was about the same as PANEL. That's how I found out.

I didn't know compressor is controlled by humidity as well as panel switch. Does it mean there is a humidity sensor somewhere inside the cab?

Thanks.

 

Nah, no humidity sensor, that's just default operation.

 

I may well have overread that. The AC compressor will even run with defrost on sometimes. But if its not coming on, the blend door is probably causing your issues

 

The case I was asking about was AC coming on not only at DEFROST but also at PANEL and FLOOR. Thanks for explaining the potential trouble spot. When it happens, I will know immediately.

This is my only Ford. My other cars are GM and Chrysler. Thanks for the explanation.

 

For the 97, compressor operation is enabled for all selector switch positions EXCEPT PANEL, FLOOR, and OFF. Most Fords of similar vintage are the same.

It's hardwired inside the switch.

Notice I said enabled. Other factors such as temperature can keep the compressor from operating, ie, ambient temp so low that refrigerant pressure drops below the cycling switch cutoff point - around 43-44 psi.

Steve

 

Thanks. It is working okay now.