Ya.. good call ! I'll open the cap and see if I can release any pressure in the system and go from there ! Thanks for the idea's guys ! Just got in the door, and I'll head out right now and try that !

 

Tried both caps... one is located on the top of the canister ( dryer) ?? And one is on the line near the front of the truck ! Both are like a valve stem on a wheel and when I pressed the stem no pressure came out either one ! Why didn't we think of that earlier Roland ???

I'll see if I can pick up a recharge kit along the way in my travels tomorrow !

 

I would have suggested that earlier, but I was under the impression that the system had a charge. You should still should have power going into the clutch cycling pressure switch. The pressure will close the switch and apply the a/c clutch. You can also unplug this switch and jumper it with a paper clip to see if it will energize the clutch. If there was no pressure, you will need to find the source of your leak. When was the last time you added freon? Any oily lines or connections?

 

Just get the cheap azz can with the hose and gauge. Put a charge in it and take it from there. The thing will never work without refrigerant and oil. Trust me, been there, done that.

 

I've never added any freon to the system.. It has always worked awesome until now ! I'm on the road all weekend and most of next week.... I'll take a look for leaks... get it recharged.. and we'll go from there ! Thanks alot for the help guys ! I'll be away from the forum as of tomorrow afternoon !

Appreciate the help !

 

when mine was empty it took 3 16oz cans to get it up to 40psi... at $20.00 a can it aint cheap.

 

$20 a can! I pay only $7-8 for R134a. I can still buy R-12 & R-22 also. They are expensive. I have a MACS certification. I add the oil with an injector bottle on my a/c gauge set. One can should raise the system pressure high enough to engage the switch (key on,a/c on, engine off) and send power to the a/c clutch. Are you talking about the low side presure when it is operating?

 

No pressure is probably the reason the a/c clutch is not working. But even with a full system, an electrical problem will keep you "hot". That's why I suggested the wiring checks. Now we know differently. Or do we?

When diagnosing a/c problems, one of the first things I check is the freon charge. I "assumed" and you know what happens then!

 

Correct. If the freon pressure is below about 28 # on the low side the low pressure switch will be open and not allow power to flow to the clutch coil.

WARNING. you can test this by jumpering across the low pressure switch connector but if your system lost freon quickly and the compressor starts it could pull in air and contaminate the system requiring you to repair / evacuate / recharge.

I would recommend with a voltmeter you check the low pressure switch connector for 12 V using chassy ground. Check each side of the plug to chassy ground. Don't check it between the lugs. Of course make sure key and ac is on when you do this check. If you do have 12V then the system is low on freon OR the low pressure switch is defective. This is where you need a gauge set. Verify the pressures on the low side with refrigerant gauges. If your pressure is above 28# psi, and you have 12 V at the low pressure switch the compressor should at least click on. IF not do an Ohms check across the low pressure switch with ohm meter set on lowest scale. You should not have more than 1-3 ohms. If more than this the switch is defective.
On some vehicles there is a schrader valve under the low pressure switch and it can be changed without discharging. My 87 corvette was able to be changed w/o discharge. I dont' have enough info on your system to know if it is of the type to allow removal with the system charged.
(I would guess that it is).

Given you have freon above 28# power to the low pressure switch, key/ignition ac on, good low pressure switch the only item left is the clutch coil. These can also be repaired in most cases w/o discharge also.
Hope this helps.

 

yes the low side while its running, if it drops below 30psi it will disengage, I just went and looked at the cans, they were 18oz cans about twice the size of all the other ones i was looking at, the first one with the fill hose and pressure gauge was 22.99, the other two refills were 17.99 ea.

 

Is there any way to check for leaks with out pressurizing the system with freon and watching it go into the atmosphere ????? Could you pressurize with anything else ?? I obviously have a leak if there is NO pressure in the system at all ! Probably took a rock through the condenser up front or something !

Thanks guys !

 

You are correct. There is no way to check without pressure.

But I think you are on the right track. Look at the condenser for visable damage.

Be thankful you have the low pressure switch. Without it you would have burned out the compressor.

To find the leak will be difficult but not impossible.

1) Look at the system for damage.
2) Add some freon and listen for a leak.
3) Now the hard part. if 1 and 2 doesn't work.
4) Disconnect and seal both lines from the condenser.
5) Pressurize the system with freon again to see if it holds.
6) If it holds the condenser needs replacement
7) If not it has a leak elsewhere and you will have to continue to seal off sections for checking.

Sorry but I know no other way if you can't hear the leak. Use a leak detector of course before you do anything. An electronic will determine at least what section the leak is in if you can work in a garage.

Good luck.