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WC-IOM-7 • Packaged Heat Pump 39
Start Up
Scroll Compressors
a. Once each compressor has started, verify that the rotation is correct. If a
scroll compressor is rotating backwards, it will not pump and a loud
rattling sound can be observed.
b. If the electrical phasing is correct, before condemning a compressor,
interchange any two leads (at the compressor Terminal block) to check the
internal phasing. Refer to the following illustration for the compressor
terminal/phase identification. If the compressor runs backward for an
extended period (15 to 30 minutes), the motor winding can overheat and
cause the motor winding thermostat to open.
c. Check the compressor oil levels. The oil level in each compressor sight
glass should be 1/2 to 3/4 full when they are “Off”.
Note: The scroll compressor uses Trane OIL-42 without substitution. The
appropriate oil charge for a 9 and 10 Ton scroll compressor is 8 pints. For a
14 and 15 Ton scroll compressor, use 14 pints.
2. After the compressor and condenser fan have started and operated for
approximately 30 minutes, observe the operating pressures. Compare the
operating pressures to the operating pressure curve in the Service Facts.
3. Check system superheat. Follow the instruction listed on the superheat
charging curve in the Service Facts.
Superheat should be within ±5 F of the superheat chart value.
4. Repeat steps 1 through 4 for each refrigerant circuit.
5. To stop the SERVICE TEST, turn the main power disconnect switch to the
“Off” position or proceed to the next component start-up procedure. Remove
electro mechanical test mode connections (if applicable).
Heating Start-Up
1. Clamp an amp meter around one of 1st stage heater power wires at the
heater contactor.
Figure 15.