so my a/c has worked fine...
swapped out my engine with another (bent rod - eek)
dude that did the swap put the a/c compressor from the other truck on mine and it wasn't working. mine that worked is now gone (sold the old truck with it in there)...

so i bought an a/c compressor, accumulator and orifice tube. also bought 11oz of PAG oil and 60oz of 134a (requirements on this new compressor).

i know how to do the oil and 134a (put it in the high pressure tube and turn on the a/c and let it drain and switch til done - oil first).


my question is, since i know it was JUST the compressor that was bad (leaked everything out even after trying stop leak), what should i do BEFORE i do the oil and 134a recharge after i put the parts on?

should i wait a certain amount of time between the oil and 134a recharge? (this answer may be in the docu with the compressor but i don't have it at work)

do i HAVE to flush out the system since it all leaked out? buddy checked it with guages and it all leaked out last time.

should the condenser still be ok if it was just a leak in the compressor and it worked fine before?

3/23/2009 10:19:40 AM

Quote :

"put it in the high pressure tube and turn on the a/c and let it drain and switch til done - oil first"

uh, no. you put freon in the low pressure side unless you want to watch the can explode

(although the fittings won't fit so you couldn't put it in the high pressure side anyways)

and someone more knowledgable to me will answer but usually you need to put the entire system under a vacuum strong enough to get rid of any water/water vapor that has found its way into the system. that's about it though really that i know of.

[Edited on March 23, 2009 at 10:30 AM. Reason : a]

3/23/2009 10:29:15 AM

whoops - low pressure i know which port it is on my car at least haha.

i want the low side to suck in the can INTO the compressor and then out the high pressure into the other components.

[Edited on March 23, 2009 at 10:35 AM. Reason : ]

3/23/2009 10:32:01 AM

the guy that worked on mine, ran some sort of cleaner through it and then pulled a vacuum.

the reman compressor came with oil in it. listed how much on the tag. added more to meet to factory spec. new condenser was required for warranty preservation.

put everything back together and works great.

new o-rings and gaskets for the fittings and hoses.

3/23/2009 11:55:59 AM

make sure you pull a vacuum on the system for at least an hour to get all the air out, if you are changing compressors, its usuallsy easier jut to pour the oil right into the ports

3/23/2009 2:34:03 PM

so just pour the oil right into the low pressure hole w/ the tube detached?

and pulling a vaccumm to flush, i assume you bypass the compressor altogether and use a pump that circulates it for a while?

[Edited on March 23, 2009 at 2:39 PM. Reason : ]

3/23/2009 2:38:39 PM

ummm...no.

Question: did the new compressor run at all while attached to your system? If not, then you ain't gotta worry about a new condenser.

It's really best to use a pressurized flush can and reverse flush both the evaporator and condenser, along with all the lines. Orifice tube needs to be out at this point. You're lucky in that GM shit is the easiest to flush.

Never trust what's listed as far as oil goes on the compressor. If it came with oil, dump it out, remeasure, and dump into compressor. If the system takes something like 8 oz, dump 4 of it into the accumulator and the rest into the compressor inlet.

Put everything together with new o-rings lubed with PAG or Nylog AC assy lube.

You MUST pull a vacuum for at least an hour using a vacuum pump capable of pulling deep vacuum; those air venturis suck ass for the purpose. This does two things: 1. Removes air (a noncondensible gas) from the system (air REALLY reduces efficiency). 2. Removes moisture and any remaining unevaporated flushing solvent from the system by lowering the boiling point to below ambient.

then do a static fill on the low pressure side. The absolute best way to do it is by weight. I use an electronic kitchen scale. You've got to figure that you lose an ounce or two with each can change and purging the hoses.

BEFORE you turn the shit on, rotate the compressor through at least half a dozen times or more by hand. Pulse the system off and on briefly when you crank 'er up. Then let run and finish charging to the correct capacity.

Hint: a bucket of warm or hot water to submerge the can in helps empty the damn things a lot faster; the phase change turns the shit cold as hell, and slows down the fill rate.

3/23/2009 3:04:06 PM

compressor is new with NO oil.

takes 11oz of PAG and 64oz of 134a. the cans i got for oil and 134a hook into the low pressure, but i can return the oil for some that pour out to lube the o-rings (i'll need to get those) and be able to pour some directly into the accumulator.

the bad compressor DID run but it never seemed to run more for a minute at a time because the ambient temp was low outside and i assume the thermostat wasn't having it constantly run.



i called a local shop and they will do the full flush for $40. if i have them do the flush i assume i will have to pull a vacuum for 45 minutes after i install the new parts before i can fill it with 134a? i assume the oil goes in after i pull the vacuum? and NOTHING is turned on until the vacuum has been done for that time and i have the oil in it and a can of 134a hooked up to the low pressure fitting?



wish i could see this done before i attempt it hehe. i'm still waiting on my cheap mechanic to call me back to just do it for me but he hasn't called - and i'm leaving in ONE week for a cross-country move.

3/23/2009 3:21:40 PM

Just how cheap is your cheap mechanic? If you are worried about fucking something up and have never done this kind of thing before, you really need to pass or just watch from the sideline.

I usually buy my oil in bottles and pour in the system. Shit won't evaporate when you go to pull a vacuum. I don't like the pressurized cans because you can't put it where you want it.

Vacuum needs to be pulled after the oil is in (or use the pressurized cans or a bona fide oil injector) to put oil in after you pull vacuum.

look for DIY articles and read the manuals...BEFORE you do ANYTHING. Best to be educated before you start if you decide to do this by yourself. I don't know where you're gonna get a vacuum pump if you don't already have one. Mine was about a 300 dollar setback.

3/23/2009 3:38:34 PM

i've been reading a few hours on everything and i'm still in the confused state i think i'm going to call a regular mechanic and get them to do the vacuum and recharge. i'll just put on the new parts after they do the flush for $40 and have them do the rest if it is cost-effective for me to take the time to do that. i don't want to use their parts and have to bring it back into THEM if something goes wrong because i'll be in Colorado!

my cheap mechanic will do it all for $100 labor i believe.

3/23/2009 3:42:33 PM