Mitsubishi Electric PKH-2GKLA Technical & Service Manual page 42

(3) Defrost interval
The defrost interval time is determined as follows.
● Initial defrost interval is 50 minutes.
● The defrost interval after defrosting depends on the preceding defrosting time as shown below.
Defrosting operation time
3 minutes or below
3 to 7 minutes
7 to 10 minutes
10 to 15 minutes
15 minutes (Maximum)
NOTE1: If the unit stops during defrosting, the next defrost interval will be 50 minutes.
NOTE2: If a protection function works for the first time during defrosting, the compressor will stop.
After a 3-minute time delay, defrosting will restart. In this case, a 3-minute time delay is included with the defrosting time.
If the protection function works for the second time, the unit stops operation and displays the check code.
The next defrost interval will be 30 minutes.
NOTE3: When the defrosting has ended, the total time of the compressor operation is cleared.
(4) Termination conditions
Defrosting finishes when any of the following conditions are satisfied.
1 Defrosting has continued for 15 minutes.
2 Outdoor coil thermistor reads 22°C or above for the first 75 seconds after defrosting start-up.
3 Outdoor coil thermistor reads 8°C or above after the 75-second defrosting.
4 Power ON/OFF button is turned OFF during defrosting.
3-6 Actuators
(1) Bypass valve control
<Cooling mode>
1 When the unit stops due to the coil frost prevention, the bypass valve turns ON. When one hour has passed since the
compressor stopped, the bypass valve returns to OFF.
2 When the compressor operates with the bypass valve at ON for more than 30 minutes, the bypass valve turns OFF.
3 When the compressor stops with the bypass valve at OFF, the bypass valve turns ON and remains ON for three minutes.
<Heating mode>
1 When the unit starts for the first time after the circuit breaker has been turned ON, or when it starts after the compressor
OFF of 30 minutes or more, if the outdoor coil thermistor reads 12°C or more, the bypass valve turns ON.
2 When the high pressure switch (63H1) works, the bypass valve turns ON.
3 When the bypass has been ON for 30 minutes:
● If the high pressure switch has already returned, the bypass valve turns to OFF.
● If not, the fan output step keeps 70 for three minutes. Meanwhile, if the high pressure switch returns, the bypass valve
turns OFF. Otherwise the normal fan control starts.
4 When the operation mode changes or stops, the bypass valve turns ON and remains ON for three minutes.
<Defrosting operation>
1 The bypass valve is OFF.
(2) Crankcase heater control
1 With jumper wire J3
The crankcase heater is ON from when the power is turned ON until the compressor starts, and then turns ON one hour
after the compressor stops.
2 Without jumper wire J3
The crankcase heater is ON from when the power is turned ON until the compressor starts, and repeats 1-hour ON and
1-hour OFF, after the compressor stops.
OC231A
Next defrost interval
120 minutes
80 minutes
60 minutes
40 minutes
30 minutes
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