A/C compressor cycling every few seconds, now dead

[erikv11]

Step one: what is the refrigerant pressure in the system?
Step two, what is the clutch gap?

Once these two fundamental are known you can actually start the discussion.

In sweltering NJ summer heat a P80 AC compressor should be on basically all the time, no cycling at all. (To cool the heat of the debate, of course!)

[bugs11]

Ugh... my kid just IM'd me "The AC in the Volvo is dead.".

[abscate]

ITs probably lost enough charge to the point where the low pressure valve has opened, which shuts off the system. It will work right up to this point, perhaps with reduced capacity, then quit completely.

The weak part of the P80 is in the evaporator system buried under the dash though. 10 hours stupid labour to remove.

[FireFox31]

If it has sat since 2014 uncharged (to be determined) you will need a number of components replaced.

What components would need to be replaced, and why? What would fail because the system was not charged? Now that I've read a lot about the A/C system here on MVS, I will better understand your input.

I've posted a list of more general A/C questions in this new thread, hoping to answer some vague points from other threads on the forum.

[abscate]

Once all the freon leaks out, corrosion sets in , and on top of the evaporator ( the almost universal failure ) you need a new....

Compressor
Receiver dryer
Orfice tube
Condensir if you let lots of junk in
And one or two of the hoses which will self-immolate on disconnection
Add charge refrigerant and PAG oil

[Ozark Lee]

Get a set of gauges on it and see if the pressure is zero. If the pressure is zero then Steve has a good list. If it is greater than zero (as a practical matter greater than 5 or 10 PSI) then all of the really bad things have not happened yet and you can simply recharge the system and see what happens.

Refrigerant never wears out but it can become contaminated by moisture which occurs when the system goes flat. The contamination which turns to acid is the reason why the parts list is so extensive when the system equalizes to atmospheric pressure.

...Lee

[FireFox31]

Thanks guys, I appreciate your responses and am carefully considering my questions with respect for your time.

Using a manifold gauge set rented from AutoZone, I confirmed the system was at zero pressure. It has been empty for at most three years.

Is there any way for me to examine the individual components for corrosion to see if replacement is mandatory? Since the system never ran due to low pressure cut off, are there components which may not have been exposed to humid air? Or is it guaranteed that I must replace all of the listed components?

And one or two of the hoses which will self-immolate on disconnection

If contact with atmosphere has wrecked all of the major components, are all of the hoses also ruined? Can you please expand on what you mean by "self-immolate"? If I can't know in advance which hoses will fail upon disconnection, then I must order and replace all of them.

What would be the harm of putting refrigerant into this zero-pressure system? It's apparently all wrecked anyway. I could replace the dryer, shim the clutch if necessary, and have the dealership vacuum and charge it up.

Is everyone forced to spend thousands of dollars to replace their entire A/C system if reaches zero pressure during the off season? I had my engine replaced for $6000, so I can't imagine paying $3000 just for the A/C.

[abscate]

You could get away cheaper, it is NOT a bleak diagnosis that all those parts will go bad, but a couple years with no charge is not good. Hopefully, you might have kept atmospheric pressure of Freon and kept moisture out during that time

You definitely need a new dryer at $50-100 depending on source/make.

This is the cheapest way to diagnose. Buy one can of R134A with UV dye, then turn your system on with the can connected and try to find the leak with the UV flashlight. One can will be enough to pressures the system enough to turn on the compressor - if it doesn't, you either have a massive leak or it is seized up - now you are getting into some repair bills,

The environmental side of this sucks, btw, you are blowing Freon into the atmosphere which is not good for any of us. The right way is have the pros sniff it with a detector.

The evaporator on these cars is known to corrode and hole in 8-10 years, and its 10 hours of labor to R/R the dash to get that out.

If its just evao you could get away with

Evan $100
Dryer $100
10 hours 1250
Vacuum and charge $150

$1600 bill

I can loan you the pump and gauges if you want to try diagnose this cheap - catch me on my travels if you are interested.