Gas Pump Checkout Procedure - Unit On - Trane RTHD Troubleshooting Manual

Gas Pump Checkout Procedure - Unit On

60
Gas Pump - RTHD Only
To check the operation of the Gas Pump while the chiller is ON do the following
procedure:
Note: At least a 50 psi differential must exist between the evaporator and
condenser before performing this test.
1 Turn the compressor off and close the valve on the oil return line from the Gas
Pump to the compressor.
2 Back seat valve and Install gauge. Re-open to read pressure.
3 Allow the unit to start.
4 Allow the Gas Pump to enter and complete a "fill" cycle (fill solenoid will
energize).
5 Allow the Gas Pump to enter a "drain" cycle (fill solenoid will de-energize and
drain solenoid will energize). During the drain cycle de-energize the fill
solenoid. Unplug J3-1 and J3-2 from the 1A6. Verify that the correct coil is de-
energized. Or remove the electric coil from the valve (to disable the valve) and
place a screwdriver or bolt shaft through the coil center to prevent
overheating of the coil.
6 Monitor the gauge pressure at angle valve. The pressure should build toward
condensing pressure. At the completion of the drain cycle de-energize the
drain solenoid. Unplug J2-1 and J2-2 from the 1A6. Verify that the correct coil
is de-energized. Or remove the electric coil from the drain valve to disable the
valve and place a screwdriver or bolt shaft through the coil center to prevent
overheating of the coil. If the pressure holds to within 10 psi in 5 minutes, the
system is functioning normally.
7 If the pressure fails to hold near condensing pressure, there may be a
solenoid valve or a check valve leakage.
8 If the pressure falls rapidly to or near suction, either the "fill" solenoid or the
check valve is leaking by.
9 To determine if the check valve is leaking by, place a temperature probe on
each side of the check valve. Monitor the temperature differential across the
check valve during the time that the "drain" solenoid is energized. If the check
valve is leaking, the temperature differential will be very small because
condensing gas will push into the evaporator. In a properly operating system,
the temperature differential across the check valve during the drain cycle will
be about 2-4 degrees depending on operation conditions.
10 If step 8 shows that there is a leak, but step 9 indicates it is NOT related to the
check valve, the problem most likely resides in the "fill" solenoid, and it should
be replaced.
11 Before returning to service, make sure all valves and coils are returned to their
normal positions.
RLC-SVD05A-EN