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  1. #1
    Join Date
    Jan 2005
    Location
    Houston TX
    Posts
    874

    Another OT problem only smaller

    I've just started one project and now its lets keep dumping on the old guy. This one is a York M/N OT-D3-D3-C1-OJB. It is a 270 ton pony for a plant that has 2400 tons daytime. It had been offline for 3 months after a leak repair to evaporator shell were the oil line penetrates through to the oil cooler. After the repairs the chiller was way short of the 950#s of R-11 charge and the customer was extremely slow on deciding to pay for 400#s to trim the charge. That explains the 3 months downtime. The compressor is an LTH-85, the other units are all LTD-126's so there is no low pressure oil pump, high pressure oil pump, jet pump or auxiliary oil pump on this unit. Just one pump in a oil sump below the compressor. Several problems have developed. The oil heater is working 7.9 amps at 120 volts, goes off when compressor is started per design. The oil temp will drop from 135*F to 100*F within 5 minutes of starting and not come back up no matter how long it runs. The oil scavenger line seems like it is just bringing back refrigerant to the compressor housing and its dumping into the oil sump. It also has a vent solenoid on top of the compressor housing (equalizing line) to the vane inlet. I believe it is a N/O valve energized (closed) at start-up, then open after about 45 seconds through 1TR. Nowhere in the wire control diagram on the door does it show this vent sol. The 1TR timer show 4 micro switches in the wiring diagram, but in the part location diagram right next to it, there are only 3 micro switches. This is very puzzling to say the least. All the diagrams are the original from 1981. I have all the information on the LTD's style compressor, but none on the LTH. Does anyone out there have a pdf for the LTH series ? Thanks in advance-GEO
    Once in a while everything falls into place and I am able to move forward, most of the time it just falls all over the place and I can't go anywhere-GEO

  2. #2
    Join Date
    Jun 2010
    Location
    U.A. (upper Alabama)
    Posts
    856
    Vent line solenoid is to drop the pressure in the oil sump, this does two main things. 1- It helps the oil return work by the lower press. 2- It helps get some of the refrigerant out of the oil, as the eductor is bringing alot of ref. back with the oil. It closes on start-up to keep from foaming the oil and possibly sucking too much oil out of the sump with the ref. that's boiling out of the oil, both resulting in a loss of oil pressure and possible shutdown. Iv'e seen these not open and all resulting in the loss of oil in the sump, because oil did not return. Is there a thermostat on the oil cooler?

  3. #3
    Join Date
    Jan 2005
    Location
    Houston TX
    Posts
    874

    I think I know what is going on

    Thanks cperk, I know what the devices are supposed to do, how they do it and why they do it. What I don't understand is how the solenoid is not shown anywhere in the diagram and how there is a 3 switch timer (1TR) for the oil system, and the component sheet and wire diagram differ. The wire diagram shows there are 4 switches 1TR-1, 1TR-2, 1TR-3 and 1TR-4 all separate micro-switches. The component diagram only shows 3 switches, so whats up with that. The oil has so much refrigerant in it that the oil heater can't boil it all away during the off cycle. It does draw 7.9 amps at 120 volts = 950 watts = 3,243 btuh. It has not shut off (satisfied) for 2 days. The chiller has remained off during this time. I installed an hour meter between the thermostatic control and heater element to verify this.-GEO
    Once in a while everything falls into place and I am able to move forward, most of the time it just falls all over the place and I can't go anywhere-GEO

  4. #4
    Join Date
    Jan 2005
    Location
    Houston TX
    Posts
    874

    I talked with York

    Talked to York about the above mentioned problems. Their response was "We may have done an engineering design change on that model run and components" Gee, why didn't I think of that. Whoever it was is quite familiar with this site. They went on to say that York chillers are designed to only be serviced by York tech's exclusively. If I don't understand them I shouldn't touch them. Well kiss my A$$. I found the real culprit here on this chiller. The wires going from the 4 X 4 wiring box to the oil heater thermostat was shorted to the BX, but not a good ground. Just enough to reroute the amperage. After running new seal tight with higher temperature rated wire the current dropped to 6.5 amps and the oil sump temperature started to climb. I will restart it tomorrow.-GEO:
    Once in a while everything falls into place and I am able to move forward, most of the time it just falls all over the place and I can't go anywhere-GEO

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