Friedrich FPHMR18A3A Service Manual page 44

Fan Only Mode Operation
In this mode, the compressor and outdoor fan stop, indoor fan operates under the pre-setting of air volume, the louver
swing, and the indoor fan speed is defaulted to the current setting in as the Heating Mode.
Defrost
Conditions for Defrost Activation:
The following three conditions must be met to activate Defrost.
• Condition 1: Outdoor ambient sensor is below 28.4°F
• Condition 2: When the heating compressor consecutively runs for 40 minutes .
• Condition 3: The difference between the condenser coil pipe sensor outdoor ambient temperature sensor ≥10°F.
Defrosting actions:
• The compressor stops, the outdoor fan stops after a delay of 30 seconds; after 50 seconds the four-way valve is powered
off; and in 10 seconds the compressor starts and runs at "defrosting frequency".
Conditions for ending defrosting:
Defrosting ends if either of the below conditions is met.
• Condition 1: The accumulated time in defrost is longer than 12 minutes.
• Condition 2: If the temperature of outdoor coil is 57°F or higher. (EEPROM setting value in the current operating mode).
Post Defrost Cycle:
• The compressor stops, for 50 seconds later the reversing valve energizes, and another 10 seconds later the compressor
and outdoor fan start normal heating operation.
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OPERATION