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2. Remove the heater compartment access panel.
3. Adjust the time period between defrost cycles by placing the
defrost time plug in the proper position. See “Defrost Control
Board.”
■ For 30-minute intervals between defrost cycles, connect
the Defrost Time Setting Plug to the pins corresponding
to 30.
■ For 60-minute intervals between defrost cycles, connect
the Defrost Time Setting Plug to the pins corresponding
to 60 (this setting is the factory preset setting).
■ For 90-minute intervals between defrost cycles, connect
the Defrost Time Setting Plug to the pins corresponding
to 90.
4. Replace the heater compartment access panel.
5. Reconnect power.
Troubleshoot the Defrost System
The defrost control is equipped with a set of pins (labeled TEST
on control circuit board) to aid in troubleshooting the defrost
system. Connecting the test pins speeds up the defrost cycle
time by a factor of 256.
1. Disconnect power.
2. Remove control box cover.
3. Connect the test pins on the defrost control using a test
jumper wire.
NOTE: If the outdoor temperature is above 32°F, connect the
defrost sensor terminals using a test jumper wire. See
“Defrost Control Board” in the “Adjust Defrost System”
section.
4. Replace control box cover.
5. Reconnect power.
6. Start system in heating operation.
7. Time the defrost test cycle as determined by the chart. After
the corresponding defrost cycle time from the chart below
has elapsed, the reversing valve should shift to defrost mode
and the outdoor fan should stop. After 2 seconds of defrost
operation, the reversing valve should shift back to heating
operation and the outdoor fan should start.
NOTE: If this procedure is not observed, check the reversing
valve solenoid for correct operation by measuring
temperatures and pressures under heating and cooling
modes. If the reversing valve solenoid operates correctly then
replace the defrost control board. See “Sequence of
Operation.”
8. If an adjustment is required, see “Adjust Time Between
Defrost Cycles” in the “Adjust Defrost System” section.
9. Disconnect power.
10. Remove control box cover.
11. Remove jumper from test pins and jumper from defrost
sensor terminals, if used.
12. Replace control box cover.
13. Reconnect power.
WARNING
Electrical Shock Hazard
Disconnect power before servicing.
Replace all parts and panels before operating.
Failure to do so can result in death or electrical shock.
Defrost Control Setting Defrost Test Cycle Time
T1 - 30 minutes 7 seconds
T2 - 60 minutes 14 seconds
T3 - 90 minutes 21 seconds