Condenser Check Valve, Purge Check Valve, And Receiver Tank Pressure Solenoid Leak Test (Multi-Temp Units Only) - Thermo King T-500R Maintenance Manual

CONDENSER CHECK VALVE, PURGE CHECK VALVE, AND RECEIVER TANK PRESSURE
SOLENOID LEAK TEST (MULTI-TEMP UNITS ONLY)
The condenser check valve and the purge check valve prevent refrigerant from moving into the condenser when one or more
zones are in heat. A unit with a leaking condenser check valve or purge check valve will have good heating capacity when a zone
first goes into the heat mode. But, it will gradually lose heating capacity as refrigerant moves into the condenser. This problem
is more noticeable at lower ambient temperatures. Use the following procedure to test the condenser check valve and the purge
check valve.
1. Attach a gauge manifold to the suction service valve and the discharge service port. Attach another low pressure gauge to the
suction access port located in the suction line near the accumulator inlet. Attach a high pressure gauge to the service port on
the receiver tank outlet valve. Low loss fittings must be used on the hoses connected to the discharge service port and the
suction access port.
2. Operate the unit with all zones in low speed cool until the system pressures stabilize.
3. Front seat the receiver tank outlet valve and allow the low side to pump down to 0 to 5 in. Hg vacuum (0 to -17 kPa).
CAUTION: Do not run scroll compressor in a vacuum for more than 1 minute.
4. Turn the unit Off.
5. Front seat the suction service valve to isolate the low side while it is still in a vacuum.
6. Watch the low pressure gauge attached to the suction access port. The low side pressure should not rise. If it does, there could
be a leak through one (or more) of following components: hot gas solenoids, purge valve, or hot gas bypass solenoid.
7. Use the Mechanics/Premium HMI Control Panel to enter the Interface Board Test Mode. Refer to the appropriate
Microprocessor Diagnostic Manual for specific information about the Interface Board Test Mode.
8. Energize the purge valve with the Interface Board Test Mode. The discharge pressure and the low side pressure should
equalize when the purge valve is energized.
9. De-energize the purge valve with the Interface Board Test Mode when the discharge pressure and the low side pressure have
equalized.
10. Watch the gauges attached to the discharge service port and the receiver tank. The discharge pressure should not rise and the
receiver tank pressure should not fall. If the discharge pressure rises, the condenser check valve or the receiver tank pressure
solenoid is probably leaking.
a. Energize the condenser inlet solenoid with the Interface Board Test Mode and watch the discharge pressure. If the
discharge pressure stops rising, the condenser check valve is probably leaking. If the discharge pressure keeps rising,
the receiver tank pressure solenoid is probably leaking.
b. De-energize the condenser inlet solenoid with the Interface Board Test Mode
11. Energize the Zone 1 liquid line solenoid with the Interface Board Test Mode and leave it energized.
12. Crack the receiver tank outlet valve open and allow refrigerant into the low side until the low side pressure is above the
discharge pressure, but below the receiver tank pressure. Close the receiver tank outlet valve when the low side pressure is
above the discharge pressure and below the receiver tank pressure.
13. De-energize the Zone 1 liquid line solenoid with the Interface Board Test Mode.
14. Energize the purge valve with the Interface Board Test Mode and leave it energized.
15. Watch the gauge attached to the discharge service port. The discharge pressure should not rise. If the discharge pressure rises,
the purge check valve is probably leaking.
16. De-energize the purge valve with the Interface Board Test Mode.
17. Back seat the receiver tank outlet valve and suction service valve. Perform a "Refrigerant Gauge Removal" procedure.
Refrigeration Maintenance 10-30