OMM TGZ-1 TGZ 040A through TGZ 190A 79
System Service
!
Warning
To avoid injury from electric shock hazard, turn off all power before continuing with
the following service.
!
NOTICE
Anyone servicing this equipment shall comply with the requirements set forth by the
EPA concerning refrigerant reclamation and venting.
Filter-Driers
To change the filter-drier, pump the unit down by moving pumpdown switches PS1 and
PS2 to the manual pumpdown” position.
Unit Size Circuit Number Jumper Across Terminals
1 42 to 44
All Sizes
2 72 to 74
Move the control switch S1 to the “off” position. Turn off all power to the unit and
install jumpers across the terminals shown in the table. This will jump out the low
pressure control. Close the manual liquid line shutoff valve(s). Turn power to the unit
back on and restart the unit by moving the control switch S1 to the “on” position. The
unit will start pumping down past the low pressure setting. When the evaporator
pressure reaches 0 to 5 psig, (0 to 34.5 kPa) move control switch S1 to the “off”
position. Remove the jumper.
Front seat the suction line King valve(s). Remove and replace the filter-drier(s).
Evacuate the lines through the liquid line manual shutoff valve(s) to remove
noncondensables that may have entered during filter replacement. A leak check is
recommend before returning the unit to operation.
Liquid Line Solenoid Valve
The liquid line solenoid valve(s), which are responsible for automatic pumpdown
during normal unit operation, do not normally require any maintenance. However, in
the event of failure they can require replacement of the solenoid coil or of the entire
valve assembly.
The solenoid coil can be removed from the valve body without opening the refrigerant
piping by moving pumpdown switch(es) PS1 and PS2 to the “manual pumpdown”
position.
The coil can then be removed from the valve body by simply removing a nut or snap
ring located at the top of the coil. The coil can then be slipped off its mounting stud for
replacement. Be sure to replace the coil on its mounting stud before returning
pumpdown switch(es) PS1 and PS2 to the “auto pumpdown” position.
To replace the entire solenoid valve, follow the steps involved when changing a filter-
drier.
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