Defrost Cycle Example; Independent Circuit Defrost Operation; Default Mode - Trane SYMBIO 700 Troubleshooting Manual

Defrost Cycle Example

12 minutes after exiting the first defrost cycle (after power-up) the OD Air temperature is 40° and the
OD coil temperature is 30° (a 10° differential).
When the differential reaches 18° (10° X 1.8) the next defrost cycle should begin.
The unit runs for 45 minutes at OD Air temperature 40° and OD Coil temperature 30° without initiating
defrost. (this is correct operation because the OD Air to OD Coil differential is not 18°)
Lowered the OD coil temp. to 22° and defrost initiated. (40° OD Air - 22° OD Coil = 18° differential)
Raised the OD coil temp. to 72° and unit exited defrost. (40° + 47° limited to 72°)
Readjusted the OD Air temperature to 40° and the OD Coil temperature to 30° so the board would again
see a 10° differential 12 minutes after exiting defrost.
15 minutes after the previous defrost ended raised the OD Air temperature to 48° and defrost initiated.
(48° OD Air – 30° OD Coil = 18° differential)

Independent Circuit Defrost Operation

For Odyssey Independent Circuit Heat Pump units with two outdoor coil temperature
sensors, the unit will perform defrost per circuit based on its own coil temperature sensor value,
the outdoor ambient temperature, and the accumulated circuit run time.
A stage of auxiliary heat will be energized anytime either circuit is in defrost mode.
All other defrost functionality, including the diagnostic conditions, will perform as described above
independently per circuit.

Default Mode

If any Defrost Fault is active, the unit will revert to the default mode any time the unit is in the active
heat mode with compressors running.
If Both the Outdoor Air Sensor and the Coil Temperature Sensor fails, the unit will revert to the default
mode any time the unit is in the active heat mode with compressors running.
If Either the Outdoor Air Sensor or the Coil Temperature Sensor fails, the unit will revert to the default
mode if the other sensor is below the Defrost Permit Temperature.
Default Mode is 5-minute defrost cycle after each 30 minutes of cumulative compressor heating
operation.
Below is the Official Sequence of Operation
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