I do one or two a week- not hard- biggest mistake you can make is to allow dirt inside- or drop out parts, like the pistons and shoes- very hard to put back together-if you drop out a piston--they are matched and measured for shoe end play BY THE WAY. First thing I always do is to scribe a line down the outside of every component -front head, front cylinder, rear cylinder, rear head- so that I never accidentally install with a head rotated 60 degrees or 120 degrees-- that creates a "no pumper" - been there, done that once...never again....I use a chain vice grip to gently pull the cylinder halves apart- then clean with emory cloth- all sealing surfaces- all six of them- then wipe down o-ring grooves to remove sanded residue- and lube and install new o-rings-then line up all parts- with rear head in vice first- install one at a time- and lastly bolt it together and torque down the through bolts- install a new shaft seal and replace clutch assembly-- takes about 45 minutes after you have done a few and get all your tools lined up. Probably have done thirty like this- never had a comeback yet.....so I guess it works-- I used to bench check for pressure a leaks-- but after 3 or 4 good results- I get confident that it will not leak on the vehicle- so I quit bench checking-- I used to keep spares already rebuilt around -- but I prefer to give the owner back his same compressor- got to rebuild it anyway-- seemed I wouldn't keep up- would find myself not getting them done until the vehicle pulled up anyway.....oh well - I know it works- I used to really clean them good on the outside- but then who cares- it gets all greasy when you re-install it anyway on the bottom of a Caddy-- I just make sure all the internals are clean and the sealing surface are clean-- I don't have to "sell" these to a buyer-- If I did I would paint them like a "professional rebuilder" but does paint make it work and seal good???? seen a lot of rebuilt units bit the dust......
Oh and another thing-- worst thing you can do is try to rebuilt a bum pump-- so even if it a really bad leaker- I will charge the system before I remove the compressor- just to see if the pump "has a heartbeat" and is worth rebuilding---it is hell to put 2 hours into a job- just to find out the compressor was a POS to start with after you put it back on the car.......
'95 Chevy 3500 454 Dually 142,000 miles
'94 Chevy Astro Van 358,000 miles!
'86 Buick Park Ave 192,000 miles
'86 GMC S-15 Pick-up 150,000 miles
'92 Chevy Lumina Van - 265,000 miles- given to me to see how far it can go! all above are white!