While changing the oil on my truck last night, I noticed that water was draining from the A/C hose from the firewall. I have not had the A/C on for the last month. I have the dash selector set to floor or floor/vent. With the engine running, I watched the A/C compressor cycle on and off. What would cause the A/C compressor to cycle on and off when the A/C is not selected?

The A/C cycles when you have the defrost selected. This way the fluid inside gets circulated and the pump is lubricated. This is a normal operation for the A/C unit.

The problem is I do not have defrost selected. I am only using the floor selection or the floor/vent selection. In either of these, the A/C should not be running as far as I know. I am wrong on this?

I think its normal in the dual position. Mine cycles the compressor when its in the dual floor / vent position also.Change it to floor or vent alone and it does not cycle. My 02 and 05 are both the same way.

Wild and Free, this makes more sense. Not sure why the factory decided to do it this way and not put the snow flake on the dash for us.

I have always wondered why they did it that way also as its very odd. But it is what it is I guess.

My 98 ranger did the same thing when on face/floor..

I haven't noticed it on my 05, but also have listened/looked for it.

I wonder if the duty cycle is difference with the a/c switch on.

--- Update to the previous post...

Well I pulled this from my 05 Owners Manual.. It appears it only operates in the mix/defrost with the a/c off. My Ford manual specifially stated which levels it worked it.

NOTE:

The air conditioning compressor operates in

both Mix and Defrost or a blend of these modes, even if

the A/C button has not been pressed. This dehumidifies

the air to help dry the windshield.