Start the engine.
Turn the AC on.
Walk to the front of the engine (hood up of course), check to see if the clutch on the AC Compressor is engaged (running like the other pulleys).

If it is, then you have Freon in the system, but it needs to be a.) recharged/replaced or,
b.) filled to capacity
If the AC clutch is not engaged then there is no/not enough Freon in the system.

What happens in a AC system is that there is Freon stored to a specific quanity (usually found on a sticker on your condensor or radiator support bracket). Once you start the engine and "call" for AC, the power is sent to the AC Compressor to begin compressing the Freon in the system. If there is not enough Freon, it will not engage the Clutch on the AC Compressor, not circulate/compress the Freon and blow only hot air; or sometimes cool but not cold air. This happens in two ways. If there is no/not enough Freon in the system, the Low Pressure switch won't recognize the predetermined amount to engage the AC Clutch and initiate power to the Compressor. The other is if the LP swith is bad. Which again, can easily happen since it is an electric component.

You can test the LP switch with a paperclip very easily....let me know if you feel comfortable with it and I'll help you out.

If the clutch is coming on, that's good news, you just need to recharge the system to it's capacity.

Good Luck,
Ivan

 

Ivan thanks for the great Info. I do feel comfortable doing it if you would share with me. The only thing that is odd is when I turn the AC on full blast I can feel a vibration and hear noise from the engine compartment.

 

A/C: How it works.........

Components:
Compressor
Condensor
Evaporator

a/c works on the following principal:

When you compress a gas it heats up and when you un-compress it, it cools down.

First your compressor, compresses the freon which in turn heats it up.
then the compressed freon goes to your condensor, which is mounted in front of the radiator
the condensor cools down the compressed Freon, so now you have cool compressed
gas. When you re-expand it the gas still wants to cool down more, making it colder
than when you orginally compressed it. The now super cold freon goes thru the
evaporator inside the car where it releases its cold, picks up heat and goes back to the compressor
to start the cycle over again.

This is the same way your house a/c system works too.

If you're hearing noise inside the engine compartment it's most likely the compressor.
they cost couple bucks if i remember right or system just needs to be recharged probably

 

and the compressor is mounted on the front of the motor correct.

 

right, you'll see the lines running off it, in the top right corner on the 86-93's not sure on your engine.

 

as far as testing the LP switch...

again, if the clutch is coming on then you shouldn't need to do this at all...

Unplug the harness going inot the LP switch. Should be a two wire deal, nothing serous.....take a paperclip and bridge the two wires going into the harness, not the actual switch which you just unplugged from. If the AC Compressor kicks on now (engine running mind you), then you have a bad switch....$27 at any Ford house. Easy to install, but you may lose some R134A Freon.

If bridging the switch does not work, then it may be an electrical issue of the switch inside your cabin (the actual AC switch on the HVAC controls) or that there is no/not enough Freon in the system....

If that's the case, then you have a leak and the only way to nail it down would be to have a professional do a Dye leak check for you....most places around here charge $39.99 for the actual check but it's money well spent unless you have a UV light and dye

Keep us posted.

Thanks,
Ivan

 

Ivan, isn't that switch there to prevent the system from running when it's low on refridgerant? If you jump the connector, aren't you just bypassing the low refridgerant 'pretection' ? That's there to prevent the system from running the compressor without oil and killing it. I would think that you would probably need to refill the system if it works by jumping the wires. The switch could be bad but you'd probably have to test the switch. Yes?

- Jeff

 

That's exactly right...I only wanted to see if the Clutch would come on (which it would if the switch was bad) and not actually cruise around town with it like that.

Maybe I shouldn't have assumed that he wouldn't do that.


Hey, if it works, DON'T DRIVE AROUND LIKE THAT!! Go fix the switch!!!

-Ivan

 

[sm=lol.gif]

But what I meant was, would that just mean the switch is bad or could it just be that you don't have enough in the system to trip the switch and allow the compressor to come on.

- Jeff

 

Well I went down to the local checkers after work today and bought a guage and refill kit. When I checked the system it said it was over charged. Normall is 25-45 PSI and mine was around 55PSI? Any idea at what could be causing this problem?