I tried searching, so I apologize, but all I could find were random issues with the A/C and nothing about it completely failing to work. With the heat index at 116 today and in the 120s tomorrow, the urgency to find a resolution to this is high...

2 weeks ago I was driving to work with the A/C on and it just cut out on me. I had never had any problems with the system prior to this that would lead me to believe there was anything wrong. I swung by CarQuest to pick up a gauge and checked my fuses while I was there. The fuses were fine and, to my dismay, I did not find my A/C system to be low on Freon, but overcharged. I don't know how that happened as I've never added Freon to a vehicle I've ever owned (never had to). So, apparently, it was either done prior to my purchasing the vehicle in Feb '10, or someone took the liberty to fill 'er up while I had it in the body shop having the bed repaired last Fall.

I discharged the system to about 35lb (safe levels), fired it back up, but it's still not blowing cold air. Then I noticed that when I switch from vent air to A/C, that it's not even engaging. You know how you feel the engine shudder when you turn it on while at a stop? That wasn't happening, nor any "freeing of power" when turning the A/C off.

I guess what I'm looking for are troubleshooting measures for these systems so I can find out what to look for/test and narrow it down to the actual component/problem.

I work in an office so showing up at 7:30AM already stinking because I'm drenched in sweat (when it's this hot & humid, rolling the windows down does nothing but blow hot air around) sucks.

 

Beuller?

 

AC cycling switch on the accumulator. The round black cylinder on your passenger side engine compartment with the metal hoses coming out the top. There is a switch with an electrical connector on it. Just unplug the switch and use a crescent wrench to unscrew the switch. Don't worry there is a schrader valve inside so no refrigerant will escape. It should come with a new o ring that you should replace on the nipple that you see after you remove the switch. Its about a 10 dollar part.

BTW you are gonna have to refill your refrigerant. It showed high but that was just because the A/C compressor wasn't on. The exact identical mirror copy everything to the "T" happened to my mustang. After I fixed the switch I had to add two cans of R134a.

If you actually want to test this before you buy the part. Unplug that electrical connector and take a paper clip and jump the two pins of the connector with your AC on. You should see the compressor kick on. Let us know what happens.

 

Dang, you got my hopes up thinking it might be that easy... Unfortunately, that didn't resolve my problem.

But thank you for the suggestion, anyway!

 

Did you replace the switch? What did you do?

 

Yes, replaced the clutch cycling switch

 

So the compressor is not coming on at all? I don't have access to my wiring diagrams for your year but I'm looking at the ones for mine (2000).

THis is if yours is the same as mine, knowing ford its gonna be pretty similar:

The PCM has the ultimate control over your compressor.

If the cycling switch and pressure switch are on then a wire is grounded that is connected to the PCM. This tells the PCM to ground the clutch relay (also known as wide open throttle relay). This lets power go to the ac clutch to engage it. If the relay is bad, pressure switch, cutoff switch, or even the selector switch is bad it will no let the compressor engage.

Let me find the diagrams for your vehicle and it should be able to get you a plan of how to trace whats going on.

 

Here are the wiring diagrams:


First off you need to see if your selector switch is working:

Take your radio bezel off and see if the grey/yellow wire has 12V with the iginition on.
Now select AC with your switch and see if the Purple or Violet wire has 12V if it doesn't try another switch. The violet wire goes to the pcm to tell it to turn on the compressor.
If this checks out you need to use the above diagram to check the other switches and relays.

Obviously if your car is running your PCM relay is working (top left in photo).

Take out the plug to your high pressure switch. if you are getting 12v to the red yellow wire then your problem could be your pressure switch. If not it is either your relay, cycling switch (you just replaced) or something wrong with the pcm.

The diagram should help you out. IF you have any questions post them. i check here and my email notifications often.

 

Forgot what I said about the pressure switch getting 12V. I think that system just grounds and when the PCM sees 0 volts on that wire it grounds the relay.

 

Thanks, Anthony. I haven't had a chance to try this yet, because I have a half-dozen other high-urgency issues I'm dealing with (even more important than A/C in a 120-degree heat index...), but will follow-up with you once I give these steps a try.

 

I bought a 2003 ranger for my son with a 4.0. The engine was changed out and now the ac won’t come on... I’ve got 12v through the low pressure and high pressure switches but it still does not cycle on. However I did notice on the passenger side of the intake there is a yellow/red wire with a purple/green wire that comes out of the engine harness on the passenger side of the intake that plugs into a yellow and black wire that has been cut and not connected to anything. I think it’s relevant because the yellow/red wore is also on both high and low pressure switches. Any idea on where this cut yellow and black wore go to?