I have a 97 F150 with no A/C. I have checked the pressure on the coolant and it is where it is supposed to be. Problem seems to be that the clutch on the compressor is not engaging at all, but it will turn freely by hand. Can someone give me any otehr ideas of what might be wrong other than the possibility of having to replace the compressor?

 

Coolant isn't supposed to have pressure, except when the engine is warm. Do you mean the refrigerant? What was the pressure? Have you checked ALL the fuses? Does the blower work?

 

yes, I did mean the refrigerant. I cannot remember the actual pressure at teh moment, but we did charge the refrigerant and had the a/c on while we were doing so. The compressor clutch never engaged. I have checked the fuses and all are intact. The blower works as well, however I am getting nothing but hot air. Does this model have a relay that is tied to something else? I see nothing in the manual for the a/c rgarding the relays.

 

The only relay in the A/C system is for the blower.

Fuse 5 in the dash should be hot with the key in RUN. The function dial must be in MAX, NORM, or DEF to send power to the hi-pressure cutoff switch above the compressor. It should be closed (continuous/no resistance) when the compressor isn't spinning to send power to the low-pressure switch on the accumulator. It should be closed if there's more than 23psi in the system to send power to the clutch, which is grounded near the R hood hinge.