Thermo King – High Side Pump Down

This procedure combines the functions of the 3-way Valve Heat Check and the Low Side Pump down. A high side pump down procedure will check the following internal seal points:
• 3-way Valve Evaporator Seat
• Pilot Solenoid
• Compressor Discharge Check Valve
• Liquid injection valve
• Condenser side of the 3-way Valve
Purpose: A high side pump-down will allow service to the:
• High pressure cutout switch
• High pressure relief valve
• Drier and other low side components.

High Side Pump Down Procedure
1. Install a calibrated gauge manifold per “Installing and Purging a Gauge Manifold with Low Loss Fittings” on page 12.
2. Front seat the condenser pressure by-pass check valve on the 3-way valve.
3. Start the unit and enter Service Test Mode as shown by Service Procedure A34A in the MP-T Diagnostic Manual (TK
41087). Using Service Test Mode place the unit in low speed cool [tESt-LSC]
4. Front seat the receiver tank outlet valve.
5. Run until a suction pressure of 5 to10 inches vacuum is reached. Do not run the unit in a vacuum for more than 1
6. Stop unit.
7. Without starting the unit, shift the 3-way valve using Service Test Defrost Mode (tESt-dEF).
8. The 3-way Valve should shift and gauge pressures should equalize near 0 psig and not rise.
NOTE: If the system was opened for service, it should be leak tested and evacuated before opening the receiver tank outlet valve.

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