I have a 1993 Ford F150 XLT 4x4 351W, I need to service my ac system, it worked last year ,but has since leaked down. 1.. it blew cold but not really cold like I like I like it...2.It would not work on MAX Cool, when the engine rpm rise the fan would stop blowing on Max Ac, it would still work on the other settings..."Vacum Problem" ?
What steps do i need to take to get my ac blowing cold and hard, like a artic cold front....Thanks In Advance

 

If it's been converted from R12 to R134 - suggest it will never be as cold as it once was, although it should still be able to keep things more than comfortable.

If it leaked all the way down, likely need to vacuum the system to pull any moisture and air out.

Check the temperature blending door to ensure it is fully sealing off. Mine has a cable actuator door and had to adjust the clip to get a good 'thunk' of the door when going to full cold.

The typical suspect for the Max Cool issue is the white vacuum line failing. This goes from the HVAC control panel in the cab out to the recirc door on the passenger side firewall in the engine compartment. Typically fails somewhere in the engine compartment. Can either patch the line, or I just tie-wrap the damper in the recirc position and run things on Normal Cool. Pop the tie-wrap off in winter for flow-through heating.

 

I dont here that thunk your talking about and I can here what sounds like a whistle coming from under the dash..The weird part is that It will work in the Max Ac setting while parked and idling, but when you throw her in gear and head down the road as soon as she gets up to about 2500rpm or so the air just dies off to a trickle, you can then turn the setting back to regualr ac and the air resumes...Could you recommend a good service manual for my truck . I am a pretty good mechanic, and fabricator "no genius or nothing" so I prefer something intuitive with lots of illustrations and plain language...Best regards..Eric

 

Haynes you can get them at autozone,advance auto, etc.....