View Full Version : York YSC Oil Loss
duke of earl
05-19-2007, 05:04 PM
Got a trouble call today for a low oil level diagnostic. The chiller has no tower bypass and the building is 13 stories with the tower on the roof and chiller in the basement. Last night got cool (around 55) so I know why the oil migrated. I recovered the oil by loading the chiller via the procedure in the iom. By the time the oil sump was at a reasonable level the leaving chilled water temp was at setpoint so I placed the slidevalve in auto. Within a minute or so the chiller unloaded and the oil migrated out of the oil separator again. My entering condenser water temperature was stable at around 80-90 degrees when this happend. The iom calls for York "C" oil but I have heard that York said "C" oil does not fare well in this machine. I had the chiller down this winter for leak repairs and I pulled the eductors so make sure they were clear and they were. The eductor that is solenoid energized has voltage to the solenoid but the line is not sweating like the lower eductor line is coming off the bottom of the evaporator. My customer is not happy not to have the chiller running but it will not stay online and I am at the end of my rope. Thanks in advance for any help.
05-19-2007, 05:47 PM
Which version eprom do you have? The newest version forces the chiller to cycle by using minimum slide or amps to keep it loaded up and preventing this problem.
05-19-2007, 07:10 PM
You say within a minute of unloading the oil level in the separator dropped, did you go off on oil level ? What is the discharge superheat, and how is the charge in this machine. I found one overcharged once that act like what you describe.
You say cond water was stable between 80-90 when it happened, 80 to 90 doesnt sound very stable, how hard was it swinging?
05-19-2007, 08:01 PM
What did the oil in the sight glasses look like at the time you were loosing it? Did you charge it to the nameplate info after the leak repairs? I have seen this weight be 50 to 75 pounds overcharged.
duke of earl
05-19-2007, 09:33 PM
I know the eprom was upgraded once(I believe the number 20 was part of the version number). Discharge superheat before unloading was about 35. The ECWT was between 80-90 (not fluctuating rapidly but more gradual as the load changed). The oil looked non foamy at times and foamy at others while pulling the chilled water loop down. I didn't see the condition just before it shut down. I did not charge to nameplate (600 lbs).I charged about 100 lbs. shy of nameplate based on another post by absorbertech.Thanks guys!
05-19-2007, 10:35 PM
Check the solenoid for direction orientation, if the oriation is reversed, most solenoids will act like check valve, b/c they cant overcome the pressure diferential. Had that happen to me once on an overhaul. The oil would migrate in a hurry. Put the orientation with the flow, and problem solved.
05-20-2007, 12:42 AM
I know the later EPROM versions on the YS Microcomputer have a 30 second time-out on a 'low separator oil level' trip to prevent nuisance tripping,page 28 in 160.47.01 manual.Maybe you can install a timer across the level switch?
Probably no help if the operating conditions don't change though.
Did you need to add oil to make switch make or jumper?
Or was switch made when you arrived but unit was locked out?
05-20-2007, 12:52 AM
I wonder if you have seperator issues? Is this the seperator with the removable end? Seems like rapid oil loss with the conditions your running.
05-20-2007, 09:01 PM
I've read before that if the screws on the compressor are worn out that it can cause oil issues, probably doesnt apply here but something to consider.
duke of earl
05-20-2007, 09:48 PM
Went back to the job today with another tech and we got the chiller started. One stood in front of Code Pack while the other watched sightglasses on separator. While being loaded (about 80%)after some runtime the oil level dropped again so we loaded to 100% and a surge of oil came back within a few seconds and filled the lower sightglass. We did find that the tower fan temperature controller located near the chiller had a 15 degree differential so we replaced it with one that has a 3-10 adjustable differential. This should help stabilize the condenser water temperature. We finally added a couple more gallons of oil and this seemed to be the ticket for now. The chiller unloaded and the oil level stayed constant. I believe by adding a tower bypass and tweaking oil/refrigerant charge things should come around. I am waiting for some hot weather so I can get a full load on the machine to check charge. Thanks for all your help guys.
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