Suction Pressure Regulator (SPR) Adjustment Procedures - MAX Important: Using the absence of bubbles in the sight glass as an indicator of correct refrigerant charge can be misleading, YOU MUST refrigerate the box to 0-5єC (32-41єF) to get a more precise indication from the sight glass. WARNING Equipment Damage! Lower settings can be selected based on local preferences to optimize heating operation. HIGHER valve settings than specified will lead to system malfunction including operation interruption when box is warm (motor overcurrent conflict with inverter limits). Important: All new unit installations require these adjustment procedures.
Failure to do so may not allow the unit to operate at its maximum capacity. Note: The following procedures are for initial settings. Sometimes conditions such as high or low ambient temperatures may require that the settings be fine-tuned for optimum performance. MAX units are equipped with a SPR valve located in the evaporator (See illustration below). The valve is used to limit the load on the compressor. This also affects the current draw of the electric motor. 1. Install gauge manifold set onto the suction service port at the compressor (See illustration below). 2.
Attach an additional compound gauge on suction service port located on copper suction tube in evaporator to monitor suction pressure going to the SPR valve (See illustration below). 3. Connect standby power receptacle to an appropriate electric power source. 4. Place jumper wire between the 12 and CHB wires at the defrost termination switch to verify the unit will run in defrost. 5. Start unit and run in defrost on the electric compressor until the pressure on the additional compound gauge attached to the suction service port stabilizes at a pressure above 45 psig (310 kPa). 6. Check the suction pressure on the gauge attached to the service port at the electric compressor.
It should be not higher than 40 +-2psig ( 275kPa +-14kPa). 8. Remove gauge manifold set, the additional compound gauge, and the jumper wire when finished with the procedure. 7. If the pressure is not within range, remove the protective cap and adjust the SPR valve to the correct setting. TK 56881-18-IM-EN 33 1. SPR Valve 2. Service Port E-200 3. Service Port Evaporator