(&*^$#! OIL FAIL!!

[markettech]

Got a 3D 15HP 404A Med temp body on a parallel rack that has failed on oil 3 times now in the last 5 weeks or so. Always runs for at least a week after reset. It's got a Sentronic as well as a current relay which takes the control circuit out on an overload fail.

Here's where I've been (today):

Cleaned screen in Sentronic sensor
Removed and cleaned oil screen
Checked current relay - operating ok
Contactor replaced in first week of January
Oil level 1/2 sight glass - doesn't fluctuate
Net oil pressure 62psig
Amp draw 18 - RLA 29
No gas defrost circuits in the area of this body as I have seen a valve stick and wash out the oil.
No circuits flooding back on the rack.

What am I missing?

E2 just installed at this store within the last 3 months.

[cold in alberta]

hey market do you guys have condenser splitting on this rack

[luvcldair]

Well
Mark you got me thinking on this one.

I had a similar problem a couple years ago, what i ended up tracing it down to was, when they went through the store they were washing down the cases and coils with hot water and it was washung out the oil under these conditions and it didnt happen very often...The washing that is...

You have gone throught the screen in the side of the compressor right the one for the oil?

Also you have checked the in-line oil strainer from the oil tank before the oil controls?

Does this compressor have any unloading?

Your sure one side of the contactor isnt dropping out ?

Just trying to give some ideas or areas to look into..

If I think of any more or i get a bright idea ill let you know...

Nothing worse than an intrmitant problem...

Hope it helps

[markettech]

Originally posted by cold in alberta
hey market do you guys have condenser splitting on this rack


Yes...splits at 55F ambient if I'm not mistaken.......Maybe 50F - I can't remember exactly but its around there.

[cold in alberta]

do you have the times of the oil failures-is it possilble the condenser unsplit right before the oil failure?

[markettech]

Originally posted by luvcldair
Well
Mark you got me thinking on this one.

I had a similar problem a couple years ago, what i ended up tracing it down to was, when they went through the store they were washing down the cases and coils with hot water and it was washung out the oil under these conditions and it didnt happen very often...The washing that is...

You have gone throught the screen in the side of the compressor right the one for the oil?
yes

Also you have checked the in-line oil strainer from the oil tank before the oil controls?
yes

Does this compressor have any unloading?
No

Your sure one side of the contactor isnt dropping out ?
I don't think so but wouldn't bet my life on it

Just trying to give some ideas or areas to look into..

If I think of any more or i get a bright idea ill let you know...

Nothing worse than an intrmitant problem...

Hope it helps



This is gonna sound hoakie, but I had a problem like this a few years back on a frozen food truck. Changed Sentronic - same problem. Put a mechanical control on it and hasn't tripped since.

[markettech]

Originally posted by cold in alberta
do you have the times of the oil failures-is it possilble the condenser unsplit right before the oil failure?

I don't know that its been warm enough for the condensor to switch to full - but I get where you're coming from. Never thought to log it. I'll check it out tomorrow if I can get back. Unfortunately store isn't set to dial up yet.

[luvcldair]

Something else that strikes me as wierd is the 62 psi net seems kinda high....

[cold in alberta]

market-also tried everything at one store a few years back-finally ran across the copeland rep at a seminar and told him my problems-his first response was what year was the store built-i told him and he said change the sentronic-they had had a bad batch with intermittent problems but were trying to kep it quiet.if all else fails change it-soon your labor will add up o more than the cost to try it.

[markettech]

As I'm thinking this through - E2 was installed and set up by one of our seasoned veterans who is just getting into the installation and programming end of things.

I remember glancing at the circuit schedule and seeing 2 med. temp circuits in defrost at the same time. I don't think there are more than 6 or 7 on the med. side of the split header.

If the defrosts aren't staggered properly maybe it's causing the load to bottom out at certain times and affect this body for some reason. But it still doesn't explain why it runs for 7 to 10 days before giving up the ghost.

I can feel my hair turning grey.

Alberta...I saw your post as I'm typing this. If it trips again I think the next step would be to change the control. In the meantime I'll double check the programming...http://www.websmileys.com/sm/sad/1050.gif

If you guys think of anything else let me know!

[cold in alberta]

let me know how it works out-nothing like intermittent oil problems

[-frozen-ocean-]

why would the condenser split be the cause of the oil trip?
i don't know please explain. is it when it goes to full condenser? how would you determine this problem?

[gerryboy00]

here is what I would do.

since it is a parallel rack (mean multiple compressors)
I would interchange the complete oil failure control/harness/sensor with another compressor and see if the problem follow the control or stay with the same compressor.



no parts cost 1/2 hrs labour...easy troubleshouting

[Edited by gerryboy00 on 01-31-2006 at 12:11 AM]

[gerryboy00]

Originally posted by -frozen-ocean-
why would the condenser split be the cause of the oil trip?
i don't know please explain. is it when it goes to full condenser? how would you determine this problem?


when splitting, liquid from the recovery line.

[thegoodhumorman]

Gerryboy is King!






right on the money!
If the comp is short cycling the sentronic will log the little bursts of run time and could drop it out.


I too have dumped sentronic for mech and problem disappeared.
Course have done it and still fails other times but well worth the shot.

on pumpout of cond split- same could be said of reclaim condenser- have seen racks tapping the pumpout to same line as OCV- not good.

[Edited by thegoodhumorman on 01-31-2006 at 12:22 AM]

[drcool2002]

What about blowby in the cylinder? Higher crankcase pressure.. could close the internal oil return check valve.
just another possiblily if the oil fail switch over doesn't work.

[Dowadudda]

Originally posted by luvcldair
Well
Mark you got me thinking on this one.

I had a similar problem a couple years ago, what i ended up tracing it down to was, when they went through the store they were washing down the cases and coils with hot water and it was washung out the oil under these conditions and it didnt happen very often...The washing that is...

You have gone throught the screen in the side of the compressor right the one for the oil?

Also you have checked the in-line oil strainer from the oil tank before the oil controls?

Does this compressor have any unloading?

Your sure one side of the contactor isnt dropping out ?

Just trying to give some ideas or areas to look into..

If I think of any more or i get a bright idea ill let you know...

Nothing worse than an intrmitant problem...

Hope it helps



what chain cleans there cases anymore?

[Dowadudda]

Originally posted by gerryboy00

Originally posted by -frozen-ocean-
why would the condenser split be the cause of the oil trip?
i don't know please explain. is it when it goes to full condenser? how would you determine this problem?


when splitting, liquid from the recovery line.

seen that too.

does this have controller, maybe to associate the time of oil fail to a splitting sequence?

[Dowadudda]

Originally posted by gerryboy00
here is what I would do.

since it is a parallel rack (mean multiple compressors)
I would interchange the complete oil failure control/harness/sensor with another compressor and see if the problem follow the control or stay with the same compressor.



no parts cost 1/2 hrs labour...easy troubleshouting

[Edited by gerryboy00 on 01-31-2006 at 12:11 AM]

Now thats a fine idea. Sometimes things like gerryboy is suggesting can be an easy way to eliminate things as you go. Don't get all uptight. Every man who has ever worked on a rack with intermittent oil fails can empathize with you and we understand. And your boss does too, even though he might be pissed. We all go through this if you do racks.

[thegoodhumorman]

Originally posted by Dowadudda
]

what chain cleans there cases anymore?

[/B]

Have the good luck to be servicing a chain that does just that- they still have PORTERS..!!!!!

Amen! Got another chain out here that is inhouse and keep up on cases pretty good, but other than meat dept they gotta point it out.

Luxury!

[markettech]

Originally posted by gerryboy00
here is what I would do.

since it is a parallel rack (mean multiple compressors)
I would interchange the complete oil failure control/harness/sensor with another compressor and see if the problem follow the control or stay with the same compressor.



no parts cost 1/2 hrs labour...easy troubleshouting

[Edited by gerryboy00 on 01-31-2006 at 12:11 AM]

Excellent idea. Should have done that the second time it tripped.

That being said, shouldn't have been in such a hurry the first two times (hit reset, checked net oil, oil level, amp draw and gone). The person who doesn't have time to do it right the first time always seems to have time to go back and do it again. :D

[Freezeking2000]

Originally posted by drcool2002
What about blowby in the cylinder? Higher crankcase pressure.. could close the internal oil return check valve.
just another possiblily if the oil fail switch over doesn't work.

Do a valve check on the compressor by closing off the suction and oil feed line and see if your discharge gas is blowing thru ......i think it is!

[markettech]

3D's have been notorious for killing reads/valve plates (until lazer reads came out)- but in my experience the body will get pretty damn hot and pull higher than expected amps. That is not the case here however.

Appreciate the input and anything is worth looking into at this point. - Thanks

[rocket]

more than likely you have flooded starts
that is migration during off cycle
check pump down solenoid, cc heater, acuumulator

note: 62 lbs net oil pressure not right the
oil pump by passes at 55 lbs. You are probably
measuring suction to oil outlet but you should
meaure crankcase to oil outlet. Both Copeland and
Carrier say "crankcase to oil outlet", no manufacturer
says "suction to oil outlet" for net oil pressure.
Mechanics do it wrong because someone forgot to put
schraeder on crankcase, then they say "well suction
and crankcase should be same pressure" like it is OK.
BlowBY means dead compressor, also means crankcase
and suction not same pressure.

You measure suction to crankcase pressure to see
signs of cyl wall, piston ring damage
(must be less than 3 lbs)
your 62 lbs suggests more than 3 lbs diff (i.e. too late)

[gerryboy00]

from Copeland website


[[[[[[]]]]]]]

Q14. What needs to be checked when an erratic oil pressure control trips?
ANSWER: First, we must recognize that there is no such thing as a nuisance oil control trip. The tripped control is warning you of an existing problem. The system should not be reset until you have looked in the sight glass and recorded the level.

If the oil is below the glass, the system should be checked for leaks or oil logging. Investigate for the oil return problem. This could be corrected by longer or more defrost cycles, reducing short cycling, preventing low refrigerant charge, eliminating piping problems, etc. If it is determined that oil should be added it must be removed once the problem is remedied.

If the oil is above the glass, the system should be checked for the possibility of refrigerant diluting the oil. Liquid refrigerant floodback could be identified by absence of superheat at the compressor. It would be advisable to separate the refrigerant from the oil by heating the oil with a crankcase heater a few hours before starting or by jogging the compressor (quick start/stop of the compressor several times) until the foaming is controlled. Remember the suction service valve should not be closed while jogging the compressor. If the valve is closed the refrigerant and oil could manage a more violent explosion (flooded start) as there is less space for the initial start-up pressure to be pulled from.

If the oil level is in the sight glass, the oil may be checked if it is too hot. Identify this by checking the temperature six inches out on the discharge line. The maximum is 225°F (107.2oC) at this distance. Any higher temperatures could mean that the cylinder temperature is above 300°F (148.9oC) and it could cause oil control trips. If the oil is foaming excessively it may have refrigerant dilution and may be identified as a floodback problem. On refrigerant cooled semi-hermetic compressors, the problem could be an over-pressurized crankcase. The root of this problem is overheat that causes excessive crankcase pressures due to piston blow by at low loads. The problem may be found by attaching a gauge manifold set to the crankcase and the suction. With the compressor operating, start slowly front seating the suction service valve. Observation of the gages should show both falling at an equal amount until the valve is fully front seated. The point at which the crankcase gauge stops falling is proof that the crankcase blow by pressure exceeds the venting.

[gerryboy00]

still


[[[[[]]]]]

Q17. What is considered good oil pressure?
ANSWER: Good oil pressure is 20-60 psid, this is the differential between crankcase and oil pump discharge.

[mspanky]

I recently had a similar problem. It also was on a rack that never seemed to flood, and no gas defrost systems close to the nuisance compressor.

Out of frustration of trying everything else, I strapped a dozen temp sensors on all the circuits immediatedly before the suction header and the compressor itself. Logged them all every 45 sec. on the RMCC and set alarm notices to 40 degree low limit.

Sure enough, a gas defrost system on the opposite side of the header had a dying fan delay that caused major floodback for about 90 sec. then immediately returned to normal.

The compressor suction stub inside the header must be a hair lower than the rest or some other physics phenomenom, to have not crashed the other pumps.

Good luck catching this one by accident. Anyway, problem solved.

Log the crap out of everything imaginable and you will catch the culprit.

[Edited by mspanky on 01-31-2006 at 06:43 PM]

[gerryboy00]

good post mspanky, I've seen that too

[markettech]

Originally posted by rocket
more than likely you have flooded starts
that is migration during off cycle
check pump down solenoid, cc heater, acuumulator

note: 62 lbs net oil pressure not right the
oil pump by passes at 55 lbs. You are probably
measuring suction to oil outlet but you should
meaure crankcase to oil outlet. Both Copeland and
Carrier say "crankcase to oil outlet", no manufacturer
says "suction to oil outlet" for net oil pressure.
Mechanics do it wrong because someone forgot to put
schraeder on crankcase, then they say "well suction
and crankcase should be same pressure" like it is OK.
BlowBY means dead compressor, also means crankcase
and suction not same pressure.

You measure suction to crankcase pressure to see
signs of cyl wall, piston ring damage
(must be less than 3 lbs)
your 62 lbs suggests more than 3 lbs diff (i.e. too late)


Thanks for the input! This compressor is on split header rack system with 3 low and 3 medium temp. compressors. No pump-down solenoid. Accumulator is at the end of the header (meaning #3 body would get flooded before #2 - which is the one I'm having problems with), and there is no crankcase heater on this indoor rack.

As far as the net oil pressure thing, had guage on suction service valve and outlet of oil pump. Might be a psig or 2 discrepancy in dials but what I read is what I read (pressure drop not uncommon in supermarket circuits depending on lenght of run and amount of ells). I've also seen many compressor oil pumps run at 55-58 psig net. Didn't think a whole lot of 62psig at the time - worth looking into though. Thanks again for the input.

[markettech]

Stopped in yesterday morning to check system quick. Damn compressor tripped again around 0500. Condensor was in split the whole time.

Took Gerryboy's advice and switched complete Sentronic/sensor with group 2 comp. 1. Also noticed 6 circuits on med. temp. side with fresh meat line-up as one of them. Suction had been set up at 52 psig (+17F R404A). Compressors were cycling often yesterday morning.

I also pulled the head and inspected the reeds and valve plate as a whole. Everything ok.

Reset suction to 44 psig (+10F). Rack seemed to mellow out and #3 body started to do most of the work.

[stanbyyourword]

hello all! first post here,long time reader, great site full of many heartfelt professionals and knowledge! the intermittent oil failures can be the most frustrating callbacks!!
a little off subject but i remember some years back , i was a lead tech at a company 80% heavy refrigeration, had one specific incident w medium size walk in cooler 2 20hp copelands (seperate cond units),3 evaps each, heatcraft i think, well one would trip out almost daily , everything checked!! evaps clean ,oil pump, superheat ,pump down, valves tested check if hold , amps , all 100%medium temp btw.
oil level, would stop in to check many times over 3 weeks , at all different times early morning afternoon evening.
sometimes would be tripped , cc empty , other times full purring away, so that ruled out faulty oil failure, at the end of day installed oil seperator!! needless to say this fixed it for good, :P but was at odds w boss , he wanted me to change over valve plates which i declined , a well experienced guy , but said this was a symptom sometimes but couldnt really explain it, a type of blow by , and haveing since asked a couple of oldtimers on occasion to this phenomenon, a couple have said yes bad discharge valves can sometimes pump out oil , but why would it be so sporadic, and if a design or defrost issue why not other unit etc, but im still in the dark to a degree around this 12 years later , compressor pumped and held beautifully , can anyone elaborate? good luck markettech , keep it simple regards sz

[Edited by stanbyyourword on 02-01-2006 at 10:09 AM]

[R12rules]

#1) check your suction pressure on crankcase of compressor, not the suction service port.
Reason being, you could have blow by on the rings of one jug and this would elevate your low side reading. It's good to also check your low side pressure @ your suction service port, but just to verify you have the same pressure as your crank case.

#2) I've never seen net oil pressure that high. Something is amiss, in my opinion.

[R12rules]

Stand by, welcome!

You'll love it here.



Have you visited Dice's thread: 9mm ?


You get a special prize if you post there. (but ya first got to read all the posts BEFORE you write yours) :D


Contact me for a listing of the prizes being offered :)


Oh ... and watch out for the maskot. Jack bites.

[markettech]

Originally posted by gerryboy00
The problem may be found by attaching a gauge manifold set to the crankcase and the suction. With the compressor operating, start slowly front seating the suction service valve. Observation of the gages should show both falling at an equal amount until the valve is fully front seated. The point at which the crankcase gauge stops falling is proof that the crankcase blow by pressure exceeds the venting.



Originally posted by R12rules

#1) check your suction pressure on crankcase of compressor, not the suction service port.
Reason being, you could have blow by on the rings of one jug and this would elevate your low side reading. It's good to also check your low side pressure @ your suction service port, but just to verify you have the same pressure as your crank case.

Good stuff guys! Thanks for the help. I did stop back around 1600 today. Compressor purring along. Checked cycle log - yesterday 372 cycles, today 32.

[gerryboy00]

Originally posted by markettech


Checked cycle log - yesterday 372 cycles, today 32.

CYCLE-CYCLE-CYCLE- AND SHORT :D

Each time a compressor starts, there is a quick
reduction in the suction pressure and therefore the
crankcase pressure. The pressure drop causes a
reduction in the saturation temperature, resulting in
the oil-refrigerant mixture flashing into foam and
vapor with the frequent result that a large percentage
of the crankcase oil is pumped out of the
compressor.
If this short cycle is repeated and repeated.....
the compressor will progressively
pump oil from the crankcase, and the
entire oil charge can be lost from the crankcase.

[markettech]

Originally posted by gerryboy00

Originally posted by markettech


Checked cycle log - yesterday 372 cycles, today 32.

CYCLE-CYCLE-CYCLE- AND SHORT :D

Each time a compressor starts, there is a quick
reduction in the suction pressure and therefore the
crankcase pressure. The pressure drop causes a
reduction in the saturation temperature, resulting in
the oil-refrigerant mixture flashing into foam and
vapor with the frequent result that a large percentage
of the crankcase oil is pumped out of the
compressor.
If this short cycle is repeated and repeated.....
the compressor will progressively
pump oil from the crankcase, and the
entire oil charge can be lost from the crankcase.




Even with an oil float?

[gerryboy00]

Originally posted by markettech


Even with an oil float?


why not?

if applicable

-if oil float strainer is block-partially block
-if oil filter (in oil line)is block-partially block
-if oil control valve (Differential type Y)is block-partially block
-if oil control valve is inoperating or differential pressure is too low
-if oil RESERVOIR is empty
-if press. differential check valve installed in the vent line is not operating.
-if....

[markettech]

Originally posted by gerryboy00
[QUOTE]

why not?

if applicable

-if oil float strainer is block-partially block
-if oil filter (in oil line)is block-partially block
-if oil control valve (Differential type Y)is block-partially block
-if oil control valve is inoperating or differential pressure is too low
-if oil RESERVOIR is empty
-if press. differential check valve installed in the vent line is not operating.
-if....

..........Good point

[basser]

Alot of good info here. Concentrate on on couple points. Net oil pressure is too high, which tells me it is not being checked correctly. Why is it 62#? Also if your are short cycling, that may be caught by the Sentronic. (by its memory). One last point, check amp draw 18 of 29 RLA tells me nothing. Is 18 amps proper amp draw? Also what is the discharge line temperature reading? Should be below 225°F.

On a 3D, the crankcase to suction pressure will be about the same. But the crankcase should never be higher then the suction. When you close the suction service valve be sure the gauges come all the way down together like stated above.

Keep us informed. Thanks.