My truck ('05 5.4) stopped blowing cold air this morning. I noticed that the compressor is not kicking on when I hit the "A/C" switch on and off. On past trucks, I've had bad high or low pressure switches...I'd like to check them on this truck.

Can someone point me in the right direction and offer opinions on other culprits that I can try to fix at home before sending her into the shop.

Thanks,
Colin

 

I assume you mean that the little green LED light is also not coming on? Do you know some one with a set of guages for 134A? The static pressure should be in the broad range of the outside air temperature. If the pressure is OK, next, (and NO, I'm not nuts ), with the engine running, turn your fan to at least 2 and press the A/C button and slap the top of the dash on the R side (a substantial slap or 2) This is assuming you've already checked all of the fuses in the system. NEVER just visually check a fuse, remove it and reinsert a couple or 3 times and then check with a volt meter. If everything else is CONFIRMED good (FIRST!) and the slap on the top of the dash brings it to life, I'll explain what's going on.

(remember, when you 1st push the A/C button, you won't know whether it's in on or off position if the green light doesn't come on, so press the button again and try the slap again if it doesn't work the 1st. time around)

 

http://www.ford-trucks.com/forums/98...self-test.html