Question about 06D compressor change out

[747ken]

I have a question about changing out a Carlyle 06D semi-hermetic compressor.

I was working on an R-22 a/c unit that uses an 06D compressor. The compressor was leaking oil from the bottom cover and had to be replaced. Otherwise the unit was working fine. I began by allowing the system to pump down, then front-seating the suction and discharge service valves. I then recovered the refrigerant from the compressor and diconnected both suction and discharge valves to ready the compressor for removal. At this point the rest of the system still contained refrigerant. It was at the end of the shift, and I was going to leave things as they were and continue the next day.

A co-worker told me this was a bad procedure. He said the suction and discharge valves were not designed to hold refrigerant against leakage. He said the valves do not use rubber components to make a seal, but rather metal to metal contact, that would have allowed much, if not all, of the refrigerant to escape if left overnight. He said ALL the refrigerant should be recovered befor changing out the compressor.

Is my co-worker right? This was my first time doing a change-out.

[r404a]

747,

This is a question that requires one answer first. Did you pull the compressor already, leaving just the shut off service valve in place, or is the compressor still there, with the valves shut but still bolted on? Here is the deal, if the compressor is still in place, I feel a little better, if not, I don't. As to the subject of the valve itself, or actually, the valves, I believ that they most certainly are designed to hold back the refrigerant, in its entirety. However, in some situations, ie, burnouts, or otherwise unfavorable condionts, the valve seats can be scored, galled or what have you. You don't get a good seal, you don't get a good vacuum. Here is my advise. If this is an inhouse job and package unit (especially) always pull the charge and weigh in the new charge. I hope that all goes well with this job. Take care and Goodluck.

r404a

[maxster]

if the system is stablized(off)the pressures would be balanced from the suction service back thru the system to the discharge.your 100% right on that closing and removal then when you reinstall do a vac on the compressor and reopen and your good to go.one way to check if they leak prior to pull out...do your recovery then let it sit... "reclaimer isolated" and see if it rises in say 30 minutes,if there is a loss it would be minimal due to pressure being equalized to the ambient of the unit.

[Diceman]

Your coworker is an idiot.

[airworx]

ive change many like this. if they are leaking it would be a lot easier to get a blankoff plate and gasket than recovering all the refrigerant.

[maxster]

trane on their semi-hermetic compressors had a plastic seat ring on the service valves within..it was like an oil filter tighting go in with the service wrench make contact and give it a little more 1/4...1/2 to lock up.they did crack from over tighting with other techs on them and a 10" adjustable but when they leaked by that pressure was constant as if opened.guys on this site can tell you to go in and change just a hi or low control and those oil safty controls....a tight service valve to flip the control capillary is an easy job,with 5-10 psi on the compressor body...no Vac hump or big time recovery on a friday night.

[freonrick]

If it was running good and only leaking oil why not just regasket the compressor?

[flange]

if we had to pull complete charge every time we changed a compressor we wouldnt have any time left over to drink beer. its pretty easy to find out if your service valves work. second the dice comment.

[747ken]

Thanks for everyone's help. I've learned a lot from you guys. Except Diceman - I already knew my co-worker is an idiot!

Next time I'll isolate the reclaimer and see if the pressure rises. Makes good sense. The backing plates with gaskets sounds like a good idea also.

freonrick:
The compressor is mounted within a fiberglass housing, so getting to the bottom cover is impossible without removing the compressor first. Bad design, but that's what we have to work with.

Another question:

I've seen 3 of these 06Ds leak oil from the bottom cover. What causes this? Bad gasket, or is something internal causing over-pressure of the oil, resulting in leaks?

[maxster]

keep it in mind the oil might have a freon mix in it may cause a slight pressure rise.it will be routine after you get your procedure down.another trick....guages on compressor,shut the suction service as to pump down,and push the contactor in manually get the suction to ZERO... contactor off,then quick shut on the discharge valve to isolate the line no reclaim needed!

[Edited by maxster on 01-17-2006 at 06:23 PM]

[747ken]

Originally posted by maxster
another trick....guages on compressor,shut the suction service as to pump down,and push the contactor in manually get the suction to ZERO... contactor off,then quick shut on the discharge valve to isolate the line no reclaim needed!



Thanks, maxster, sounds like a great tip.

[absrbrtek]

Thats my question. You have to pull it out either way.

Originally posted by freonrick
If it was running good and only leaking oil why not just regasket the compressor?

[joeywpittman]

It may appear that the bottom crank case gasket is leaking because it is covered in oil. If there is a leak somewhere above the crank case gasket (90% of the time) the oil will roll along the compressor body and collect on this over hanging gasket.

[chiller mekanik]

As several have stated,why are you replacing this compressor?
Joey makes a good point, if your not certain that the bottom gasket is actually the leaker, clean it up really good with degreaser,then wait a little bit to see where the leaks are.
Even if you have to replace all of the gaskets, its still better than replacing the compressor.(for the customer)
Sure you have to take it out to change some of the gaskets, but the re-gasketing of a compressor is a cake walk.(especially with an impact)

[maxster]

had a leaker on a Trane CGWC/W7900 years ago went the same root$$$$$ on replacing it NO! took it out and flipped it over and regasketed it what a waste of time.this unit was on a private MRI site chiller in Manhattan all nighter. suggested/told customer on original install to put a back up in but NOOOOOOOOOOO!

[747ken]

Originally posted by chiller mekanik
As several have stated,why are you replacing this compressor?
Joey makes a good point, if your not certain that the bottom gasket is actually the leaker, clean it up really good with degreaser,then wait a little bit to see where the leaks are.
Even if you have to replace all of the gaskets, its still better than replacing the compressor.

I never said that I was not certain about the location of the leak. I knew the bottom cover was leaking.

As to why the compressor is being replaced, and not repaired: the a/c unit is mounted on an passenger train, not a building. It takes some time to remove/replace a compressor. To minimize the train's down time, we just replace. Some of these compressors are still under warranty, so they go back to the vendor. This is the way management wants it done. I know this sounds like a waste of money, but I work for a state government agency, which spends money (taxpayers) like a drunken salior.

[chiller mekanik]

Thanks for the explanation.

[747ken]

Originally posted by chiller mekanik
Thanks for the explanation.

You're welcome. And thanks to you and the others who replied. I learn a lot from you folks!