Rebuilding semi-hermetric compressor

[jrc2905]

I have a small semi-hermetic compressor with a leak in the crankcase gasket. I want to replace this gasket but I deal with hermetic compressors. Removing the compressor and replacing the gasket is no problem. How does one remove non-condensables from the crankcase of the compressor and insure the proper oil charge. Thanks

[service guy]

The oil level depends on what make compressor your working on all manufactors call for different levels in the sight glass, As far as non-condensables a good vaccum pump is all you need just make sure you are adding fresh oil to the compressor don't use oil thats been in you truck for 3 years good luck!!

[fat eddy]

The way I do it and I'm sure I will catch hell over it is, Lockout all the comppressor valves put your vacuum pump on it let it pull down, then take out the heater and the gasket (while the pump is running) install new parts put it back together let the pump continue to run til you have a clean dry system, open valves back up and yur done 45 minutes. Wall Ah git-er-dun

[kerndt]

That’s Eddy. Again you have contaminated this system. How can you continue to purposely give out bad information? You have no character, or morals. You are simply evil. I wonder what your one time customers think of you?

[fat eddy]

Hey i did misread it the first time I thought he said hr crankcase heater gasket, but if he is talking about the the whole crankcase gasket then it won't work anyway.

[rimek]

The gasket on the bottom?, shut unit down, frontseat service valves and shut off any oil return piping to case, recover charge you just isolated in compressor body, Drain case(if pan gasket is the leaker) work carefully and quickly-don't forget to soak the gaskets in system oil while you are preparing. Button it back up torqueing evenly, If you're using POE, I've found that sometimes it's already wet, and needs a bit of a standing vacuum to dry. If you're on abo or 3gs, recharge- the nameplate sometimes has the charge printed on the tag(copeland usually bottom right), but use normal procedure to insure proper level using sight glass(find recommended or replace exactly what you removed-when in doubt). Since you're saying that you usually working on cans, can I guess that this is smaller than 5 HP? If you're getting a pan leak, test the oil when you take it out as well-that's not your usual spot.

Edit: oh yeah, to bring it back up to service- triple evac-use nitro for first 2 and allow to stand each time for a minute or 2 to absorb moisture, and system refrigerant for final break, then open service valves and you should have minor charge and oil adjustments. Good Luck

[Edited by rimek on 03-25-2005 at 07:40 PM]

[jrc2905]

Ok my fault I should have given a more detailed question. Yes this is a small semi-hermetic compressor. The gasket that is leaking is the round gasket at the front of the compressor. I assume the correct oil level is half way on the sight glass. I can isolate the compressor from the system with the service valves no problem. Some one added red dye to the system to try to find the leak and I would like to replace the refrigerant, and oil charge because of this dye. This unit has an oil separator, my question is, where would you add the oil to replace oil lost from the crankcase when I replace the gasket and how do you attach your service hoses and vacuum pump to the compressor to remove non-condensable from the crankcase? I have added oil to hermetic compressors with an oil pump.
I only work on hermetic compressors so you have to talk to me like I am a five year old.

[service guy]

I wouldn't worry about the dye it won't harm anything leave it in there it may help you find a leak later on.

[fat eddy]

It sounds like you are talking about a Copeland compressor judging by what you say is leaking,,

there may be a fitting on the right side of the compressor that may be an access fitting, you pump the oil with an oil pump into there, if you just need to top oil off you can pump it into the suction port on the suction valve, while it is running.

If you do not have an access fitting , then install one while you have the compresor open,

In any case consult the service book for that compressor, what I am telling you is just compressor stuff, and it may or may not apply to the one you are working on.

[thor7000]

I would not suggest adding oil to the suction valve as
Fat eddy has suggested, if it's a semi-hermetic then there should be a service tap on the oil pump were you can add the oil. As far as oil level, you need to check with the manufacturer regarding oil levels. Carrier compressors for example are very critical on oil level, usually 1/8 to 1/4 oil level...anything higher then that can damage the valves.

[rimek]

Jeez- dont pump oil into the suction valve while it's running, we don't have enough information to suggest that-if this is a small copeland k-body, the suction service valve is close to the valve on the plate-liquid slug. There is a sump connection, 1/4" fpt, usually below the suction side of the head. If you have a "can-verter" style pump, you can pump the stuff out and get it below the oil pump plate(the part that sounds like what you're describing). Some of the K's also had a drain port at the end you're on, that can make getting the rest out easy. Just try to measure what you took out and use that as a starting point. The dye shouldn't be a problem. If you have the service valves front seated, the access port should be open to the compressor body only, so there's your gauge hookups for evac. If you haven't opened one of these up-use a good work area with plenty of light-it sounds like you're working on the oil pump gasket. Watch for anything foreign. Does this unit even have an external oil pump port on it? Can you post make and model?

[fat eddy]

Hey I told him to check the book, but tell me you never put a little oil in the suction valve, c'mon don't be ridiculous.

i am thinking he is wi=orking on the crank case heater gasket, on a 4r copeland

[Edited by fat eddy on 03-25-2005 at 10:19 PM]

[AllTemp]

Be sure and check oil levels after she has run for a while. It is surprising to see how much oil may have not return to the system.

Also a drier change is important and sometimes overlooked.

[fat eddy]

When I said crankcase heater I meant the filter\magnet, down by the crankcase

[jrc2905]

Next week when I get back to the location I will get data on the compressor.

[fat eddy]

What size pipes are the discharge and the suction ? it will get us close to the type and the size, and where does the suction come in at ?

[dapper]

I'm with you on this one Eddy. Over the years I have pumped oil into every kind of compressor through the suction service valve. As far as pumping oil into the port on an oil pump while it is running...... you need one hell of a pump and some mean looking forearms to do that!!!

[fat eddy]

Yeah I hear ya,

I'm just trying to deal with the real world situation here, sometimes it ain't text book, but you need to be real about it, why would ya break your arms that way,if you can get on the suction port, I mean isn't that the path that it takes anyway ?

If you use yur head while yur doin it and not pump to much to fast I don't beleive there is a problem doing it that way,I don't think they know what a real slug looks like , it isn't the amount of oil you can pump in in one stroke it is more like 50 times that.

[service guy]

Yeah it's kinda like charging liquid in the suction we all do it however I think we all know the limits and someone doing it for the first time should have some guidance as to how to do it and whats normal and not normal.

[wasp]

If you can pump the system down by closing the liquid line king valve, do that. If it is possible to hook your suction guage to a compressor port, do that so you can see if you have a pressure rise after you isolate the compressor by closing the service valves. If you have pressure rise then you will have to recover entire charge or what is left in system.

If your pressure rises in the compressor quickly BEFORE you can valve in the service valves, then you have bad valves or piston rings in the compressor.

If the compressor has a 1/4 mpt x 1/4 flare with schrader fitting or fitting with a valve on it that would allow you to drain the oil (this fitting will be at the bottom of the compressor under the compressor's oil pump)hook a hose to it and use the remaining pressure to push the oil into an empty jug. Although if you are determined to change the oil completely and you think that your oil level is low but able to run the compressor, I would wait until the endbell gasket is changed.

Take the suction service valve off the compressor, remove the endbell ensuring that all surfaces are free of old gasket. Lube new gasket with fresh compressor oil, I use 4GS (300 viscosity) for all of my compressor work, and install gasket, reassemble compressor, pull a vacuum on the compressor.

Run the compressor and watch your oil level. If the oil level is too high, you will have to look in the sight glass with a flashlight upward and watch for oil movement. Hook a hose to the oil pump fitting (on the compressor) and while it is running, bleed oil from pump into empty jug until desired oil level--- Copeland Coplamatic 1/2 sight glass, Carrier/Carlyle 06D 1/8 to 1/4 sight glass, 06E 1/4 sight glass.

If the compressor level is too low (at bottom of sight glass) run it for awhile and see if any oil returns from the evaporator. If NO oil can be seen, add oil into oil pump port (easier with no pressure on compressor, valve in and bleed pressure, this is a diminimus amount) add oil until you see level at the bottom of sight glass. I have had to put some oil into compressors and run them to get oil back to compressor. If oil comes back and level is high, bleed until correct oil level is acheived and continue to monitor oil level. After you are satisfied that you have returned all the oil from evporator, then change the oil completely.

If you have an oil migration problem, you need to check to see if you have low building load or compressor capacity controls problems, etc. Check thermostat also, have found t-stats turned all the way down causing the compressor to run without shutting off causing oil migration.

GOOD LUCK!

[wasp]

Oh yeah, one more thing, don't pump oil into a running compressor.

[jrc2905]

To wasp,

(pull a vacuum on the compressor)

This is my question, where do you attach your service hose on the compressor to pull this vacuum and what do you pull it down to? Thanks

[dapper]

Another one with the same text book Eddy!!!

[fat eddy]

Originally posted by wasp
If you can pump the system down by closing the liquid line king valve, do that. If it is possible to hook your suction guage to a compressor port, do that so you can see if you have a pressure rise after you isolate the compressor by closing the service valves. If you have pressure rise then you will have to recover entire charge or what is left in system.

If your pressure rises in the compressor quickly BEFORE you can valve in the service valves, then you have bad valves or piston rings in the compressor.

If the compressor has a 1/4 mpt x 1/4 flare with schrader fitting or fitting with a valve on it that would allow you to drain the oil (this fitting will be at the bottom of the compressor under the compressor's oil pump)hook a hose to it and use the remaining pressure to push the oil into an empty jug. Although if you are determined to change the oil completely and you think that your oil level is low but able to run the compressor, I would wait until the endbell gasket is changed.

Take the suction service valve off the compressor, remove the endbell ensuring that all surfaces are free of old gasket. Lube new gasket with fresh compressor oil, I use 4GS (300 viscosity) for all of my compressor work, and install gasket, reassemble compressor, pull a vacuum on the compressor.

Run the compressor and watch your oil level. If the oil level is too high, you will have to look in the sight glass with a flashlight upward and watch for oil movement. Hook a hose to the oil pump fitting (on the compressor) and while it is running, bleed oil from pump into empty jug until desired oil level--- Copeland Coplamatic 1/2 sight glass, Carrier/Carlyle 06D 1/8 to 1/4 sight glass, 06E 1/4 sight glass.

If the compressor level is too low (at bottom of sight glass) run it for awhile and see if any oil returns from the evaporator. If NO oil can be seen, add oil into oil pump port (easier with no pressure on compressor, valve in and bleed pressure, this is a diminimus amount) add oil until you see level at the bottom of sight glass. I have had to put some oil into compressors and run them to get oil back to compressor. If oil comes back and level is high, bleed until correct oil level is acheived and continue to monitor oil level. After you are satisfied that you have returned all the oil from evporator, then change the oil completely.

If you have an oil migration problem, you need to check to see if you have low building load or compressor capacity controls problems, etc. Check thermostat also, have found t-stats turned all the way down causing the compressor to run without shutting off causing oil migration.

GOOD LUCK!



Just trying to clear a few things up.

"If you can pump the system down by closing the liquid line king valve, do that."

Is this regardless of the length of the liquid line ?

"If it is possible to hook your suction guage to a compressor port, do that so you can see if you have a pressure rise after you isolate the compressor by closing the service valves."

Is that how that is done ?

"If you have pressure rise then you will have to recover entire charge or what is left in system."

Why ? how does that lead to recovering whole system ?



"If your pressure rises in the compressor quickly BEFORE you can valve in the service valves, then you have bad valves or piston rings in the compressor."

That's not what that means, but I will act as though you are correct and say the following.

Is this done before or after you recovered the refrigerant in the step before it ?

and didn't the pressure rise indicate needing to recover the entire system a minute ago ?

That is as far as I'm going to go for now, I might stop back later and ask why you have "remaining pressure" to push the oil out if you ""recovered the entire system correctly ""

Right now I want to move on to your second post because that one has a lot of potentiel to cause some excitement in the industry , I think you have found out something that compressor manufacturers all over the globe have been trying to figure out for years and years,


""Oh yeah, one more thing, don't pump oil into a running compressor""

Ya see this is in direct contrast to what the manufacturers have been telling us to do , and maybe this explains why they should change their minds about it.

I am in the process of sending them a memo that I have code named ""Wasp Said" and in it I have attached your post. I am sure that they will start reprinting all of their compressor literature first thing in the morning,.,




I will forward to you, all thank yous and attaboys that they send.

[chiller mekanik]

Good one eddy!

[jimp]

Originally posted by jrc2905
I have a small semi-hermetic compressor with a leak in the crankcase gasket. I want to replace this gasket but I deal with hermetic compressors. Removing the compressor and replacing the gasket is no problem. How does one remove non-condensables from the crankcase of the compressor and insure the proper oil charge. Thanks

Why remove the compressor to replace the oil pump end gasket? Is the oil half way in the oil sight glass now?Their should be two plugs on the head where you can install acess fitting's for high and lowside, you can pull a vaccum there. On the side by the oil sight glass is another plug where you can add oil.

[wasp]

Usually these type of compressors have 1/4" service ports that you can put schrader tees on to after said system is pumped down or freon removed from compressor. I always make it a point to "accessorize" the equipment I work on, makes the job a hell of alot easier.

Pumping oil into a running compressor, even on the suction side means you are pumping against 50+ psi with the oil pump.

How long have you people been doing this kind of work?

[hvac3901]

sometimes i can't help but add my two cents..even if thats all its worth.

I can't beleive this is still going on. With the question that wasa asked

[Edited by hvac3901 on 03-29-2005 at 09:41 PM]

[wasp]

Fat Eddy and Chiller Mekanik, re-read the post, it is self explanatory.

[wasp]

JRC2905, If there is a 1/4" fitting anywhere on the compressor that you can put a schrader tee on for access to the compressor. There may be a low or high pressure switch hooked to the compressor via flare nut or even oil failure switch, add a schrader tee to that and leave the extra port on the tee for future use.

[bobby m]

Why bother not worth the trouble unless leak is large,what do you tell the customer after spending $1500 on a gasket than the compressor craps out afterwards. There is a such thing as caring to much in this buisness.No offense

[fat eddy]

I tell him exactly what I did , I repaired a leak and that leak is warranteed for thirty days,I don't think he would expect that I added anyhing to the expected life span of that compressor, if it craps out he will pay for that repair also.

[r404a]

This question may or may not have been answered by now....I don't know because my head is reeling from all of the bickering. JRC, here are a few pointers. First, do you have a SERVICE valve at the suction and discharge of this compmressor. If you do, your life is a little easier. Tag this machine out, front seat both valves and "recover" the gas from the compressor only. With these valves shut (all the way front seated) your gauges are on the "compressor" side of the system. If you are dealing with a copeland, as wasp said, look down on the crank and next to the sight glass, you should have a plugged fitting. It may have a straight slot screw or it could have a pressure switch hooked up to it. Pull this fitting. Allow the crankcase a second to see if you are blowing any vapor, if so, recheck your valves to ensure tigtness. Next, pump the oil in. If you have a 1/4" flare on there (from an existing pressure switch) you can hook a hose up from your hand pump there. Get a hand pump from the supply house. If you are mainly an AC guy and RE MIchels is in the area, you can get a nice oil line priming pump for this job. DO NOT USE AN OLD ONE THAT HAS BEEN USED TO PRIME OIL LINES, PLEASE. I think that you can figure out how to get the oil in now. Now, as to the type....quick reference, if it is an old Copeland with a red tag, mineral....like the other guys said...call Aireco or United, give them your Model and you'll know what to put in there. Start with about 1/2 sight glass and observe during run.
Next, your lowside gauge is accessing the crankcase. If your disc reeds are ok, all your highside gauge is seeing discharge cavity and top of discharge valves. IMO, the best way to check for leaks on your new fitting is shoot a little gas into the lowside, soap bubble it and then start evacuation right from the position you have your gauges in. Remember, you are JUST evacing the high and lowside of the compressor.

[r404a]

JRC,
One more thing, I don't know if this is a pump lubricated motor or not, can't tell from your post. In the event that it is, exercise extreme caution pulling of the front end, as you may snap the oil pick up tube from this thing. Good luck.
404a

[jrc2905]

I was able to contact a company rep, for this equipment, he is going to have a tech call me with the procedures for this compressor and send me all the specs too. I will post the info when I get it thanks.

[powerhead]

Doesn't anybody attach one side of a hose to an oil drain fitting or some other low pressure crankcase fitting, drop the other end into a jug of oil, pull a vacuum on the compressor and let the vacuum pump do the work of drawing the oil in? Sure beats pumping against the suction pressure any day! Save hand pumping for fine adjustments after the compressor is back in service.

[fat eddy]

Originally posted by powerhead
Doesn't anybody attach one side of a hose to an oil drain fitting or some other low pressure crankcase fitting, drop the other end into a jug of oil, pull a vacuum on the compressor and let the vacuum pump do the work of drawing the oil in? Sure beats pumping against the suction pressure any day! Save hand pumping for fine adjustments after the compressor is back in service.

I do it all the time, but he was talking about changini=g a gasket, then where to put the oil in, and I was telling him that he could top it off in the suction line while it is running,I also told him he can make the whole repair with the vacuum pump running and wouldn't have to worry about all this crap.

[wasp]

Fat Eddy and Bobby M, The extra measures that I take to troubleshoot and repair a system gives me a rough idea of the compressor life left (if any due to unit condition) and that information gets to the customer (whether he wants it fixed right then or to wait), that way when it does crap out and the customer has been given the info, he knows he has not been lied to.

Example: My company has just signed a large shopping mall due to a damning walk through and brief checkout of all equipment which included pictures of dirty filters and empty freon drums left on the roof and bypassed controls inside of the control panels of these units. By the way our bid was about 4k higher than all other bids.

Now I know your mentality: You are going to accuse me of planting evidence and such, kind of hard to do when the maintenance superintendant was up there with us and seen it first hand. But of course you don't believe me.

Honesty pays.

[fat eddy]

Wasp.

I was just yankin your chain,

[wasp]

I do tend to take my job seriously and any assistance I can offer to make someone else's job easier, and to not have a callback, I will.

Y'all still mad at me for that post I made in the America, Religion and Politics section?

I also voice my opinion (as you can tell) and that also proves I am not a brownnoser!

[fat eddy]

Not mad about ARP, thats what it is for.

[jrc2905]

Thanks for all the responses, but I think I need to rephrase my question. The Compressor is a Copelametic R-12 Motor-Compressor. Capacity 5020 btu/hr. The spec sheet does not list HP.

My question is, after I open this compressor for repairs, how do I evacuate it so there are no no-condesables in the crankcase?

[r404a]

Pull your vacuum on the compressor right at the service valves. You should have a stop valve on the suction and discharge of that compressor. If you turn each of those in all of the way to the right, you will now be accessing just the compressor and you can service it, change oil, test and evacuate all you want on JUST THE COMPRESSOR from this position. If you don't see a place to hook a gauge on these valve bodies, look real close, you may hav a pipe plug on there, maybe 1/4 or 3/8 tap that you can put an access in, but you should have access there.
r404a

[jrc2905]

So by pulling a vacuum on the head the crankcase is evacuated through the piston cylinder?

[r404a]

Yes, if you pull your vacuum on the SUCTION and DISCHARGE valves, you will evacuate this compressor.


r404a

[jrc2905]

Thanks that is what I was trying to find out. I am the kind of person who needs to know why a procedure works.