[paulkramer]

all systems leak over a period of time but if they are in good condition they should only leak about half a pound per year and the most common place for leaks is at the compressor hose connections the best way to test for leaks is with an electronic leak detector. you also said it wont engage if it has low pressure so that can be bad high and low pressure cutoff switches

Lots of potential problems here... :(

But I'm hoping - and praying - for a simple solution.

[paulkramer]

Max. charge is 19.4 oz. Sounds reasonable that it has all leaked out with age.

[this8384]

The clutch bearing goes bad, just like on a water pump or alternator.

I have to disagree with the statement that a system in good condition leaks half a pound a year. A system in good condition doesn't leak, period.

[paulkramer]

The clutch bearing goes bad, just like on a water pump or alternator.

I have to disagree with the statement that a system in good condition leaks half a pound a year. A system in good condition doesn't leak, period.

Is that the same bearing as the compressor bearing? I had one of those go bad on another car, it was obvious as it squealed full time - A/C on or off.

[Jlesnik33]

Well an easy way to check for leaks is to just look for oily residue on the system components and hoses but you said it kicks on but not under low pressure so it could either be the pulley that engages power from the engine to the compressor clutch. The pulley might be worn or it could be that the low pressure cut off switch could be bad and yes all air conditioning systems leak trace amounts of refridgerant with time

[this8384]

Are you referring to the pulley that sits on the compressor and the serpentine belt loops around? That doesn't have anything to do with "engaging power" from the engine. There's a switch that tells the clutch when to kick on and when to kick off.

[Jlesnik33]

The pulley could also have too much tension, which could cause the compressor clutch to stay disengaged

[paulkramer]

She must be referring to the clutch - IDK how the pulley can go bad, unless it rusts away

[Jlesnik33]

Okay you have no idea what your talking about.

[this8384]

the pulley could also have to much tension, which could cause the compressor clutch to stay disengaged

Um, no. Please explain how the pulley would magically begin to have too much tension on it.

[paulkramer]

the pulley could also have to much tension, which could cause the compressor clutch to stay disengaged

Tensioner indicator is within range, I replaced the serpentine belt about 20K miles ago

[Jlesnik33]

The clutch is driven by power from the engines crankshaft, which is transmitted though one or more belts to the pulley which is in operation whenever the engine is running. When the clutch is engaged power is transmitter from the pulley to the compressor shaft by the cluthe drive plate.

[this8384]

The clutch is driven by power from the engines crankshaft, which is transmitted though one or more belts to the pulley which is in operation whenever the engine is running. When the clutch is engaged power is transmitter from the pulley to the compressor shaft by the cluthe drive plate.

Oh my lord... who have you been talking to? The crankshaft does NOT drive the A/C compressor or the clutch.

[Jlesnik33]

Actually who have you been talking to that you don't understand anything that I'm saying?

[paulkramer]

Now, now...

The crank does drive the serpentine belt, which in turn drives the various accessories, including the A/C compressor.

[Jlesnik33]

Well the clutch is driven by the engine and the clutch transmits its power through the pulley which engages and disengages the compressor and when the compressor is disengaged the pulley free wheels and if your compressor sometimes kicks on the pulley may be worn, has too much tension or the clutch plate is malfunctioning and not engaging the compressor when necessary

[Jlesnik33]

It could also be an electrical problem because the clutch is designed to engage the pulley to the compressor shaft when the clutch coil is energized so if there is not enough current to energize the clutch coil the clutch will not engage the pulley to the compressor shaft and will not engage the compressor

[paulkramer]

Thanks - that's also likely considering I live in Michigan (rust belt, thanks to road salt) and the location of the compressor right above the subframe. Meaning an electrical connection could be corroded.

[Jlesnik33]

No problem, and I'm sorry I was being mean its just I went to school for it and work in a business with my girlfriend as a side job, hope all goes well, and if you need anything else I'm here

[paulkramer]

Update - took it to A/C guy, he evacuated, vacuumed, noticed and replaced a slightly leaky service port/valve on the low side, and refilled. With rides to and from work, $60.

Thanks everyone for your help.