98 SHO AC Performance Issue

[Blackdr16]

Let's see if I can pick a few brains here... Issue is as follows. AC Compressor was running however it was kicking on and off every 5 min or so. Seemed to be a little loud rattling sound coming from the compressor but the air coming out was cold when the compressor was working. Suspecting that there was a small leak I found the high pressure side valve was leaking. I replaced both high and low side valves and vacuumed down the system. Once I started charging the system it wouldn't take a whole single 12 oz can before the low side pressure would keep climbing and once it hit the top limit would **** the compressor. (Compressor started running as soon as I put the first bit of r134a in). Low side pressure would stay around 32-40 psi for about a minute then start climbing without me adding any additional r134a. Once it hit around 100 it would kick the compressor off. Here is the actual high/low psi as the scenario unfolds.

Compressor working however no cold air and the low side line off the compressor was not the least bit cold.
Low side 32-40 psi - High side 125-150 psi

Once the low side psi started climbing the high side climbed as well. Compressor continued to stay running
Low side 50-90 psi - High side 200-250 psi

If the fans would kick to high the pressures would start to drop down to normal (32-40L - 125-150H) and the compressor would continue to run. I did not try to charge more into the system as I have not seen this type of scenario before. As it sits now there is less than 12 oz in the system, the compressor will kick on and run for around 10 minutes without cycling and then stop without working again till car is turn off/on. Any thoughts or ideas from those who have experienced anything similar?

 

[Blackdr16]

Update: After waiting a day I was able to fill the system to the required 34 oz and the air started blowing cold. I am currently seeing the system work normally when engine is cold but once it is heat soaked the system stops working. I am suspecting the AC clutch at this point (could be weak or not adjusted correct) but i wont know that for sure till this weekend. I'm guessing the pressure of the cans was not enough to force the freon into the system when it was hot the other day and with the compressor kicking off (Slipping possibly) it would explain not being able to fill with the required amount of freon.

 

[98SF19]

Is compressor deshimmed?
Have you replaced blend door actuator?
Could there be constrictions in the system?
Wait till your RCC craps and your only alternative is either picking one from a junkyard that will probably not last very long, or forking over $500+ to Bob Allen Ford for a reman'd unit. That's where I am.

 

[Blackdr16]

Finally logging back in after some time away. Thanks for the reply 98SF19, It was the compressor's clutch plate that was very worn and slipping. After removing the shim it works pretty well. If its really hot or has run for some time (few hrs) it will slip some. I'll probably get another compressor and just swap the clutch assembly onto the old one since I cant find a rebuild kit anywhere and the rest of my A/C is working great. Sure is a pain to find the clutch plate anywhere, the only ones i could find were the balanced ones and not the off-balance one like this compressor requires.

 

[98SF19]

https://dl.dropboxusercontent.com/u/50438230/Shim.jpg
It's amazing how something so small can be the difference between AC and no AC. Removing it did not solve my problem, but it did allow me to thoroughly coat my neighbors clean garage floor with many many greasy handprints and smudges, all of which I had to clean up afterward.

 

[Blackdr16]

Ya its pretty crazy. Mine was really worn but just enough material that it still gets enough friction on contact not to slip until its pretty hot. I'm sure next year I'll have to find another clutch plate or buy a new compressor. Wonder if anyone has ever successfully rebuilt the clutch plate?