Carrier 38VMA Series, Service Manual, Page: 37 / 112

5. Other Control
a. Outdoor Unit Rotation
In the case of modular systems, the outdoor unit rotation is used to prevent the compressor from burning out due to unbalanced oil
level between compressors.
b. Sequence of Outdoor Unit Rotation
In the case of modular systems, each outdoor unit is given an operating priority.
Outdoor unit rotation makes it possible to change the operating priority of outdoor units. With the outdoor unit rotation control,
the system ensures that every outdoor unit has equal run hour making sure the oil is balanced between the individual outdoor unit.
c. Timing of Outdoor Unit Rotation
After oil return operation, after defrosting operation, or at system startup.
6. Cooling Operation Prohibition
Cooling operation is prohibited above 131
⁰
F ambient temperature.
Cooling operation is prohibited below 5
⁰
F ambient temperature.
7. Heating Operation Prohibition
Heating operation is prohibited above 77
⁰
F ambient temperature.
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