Toshiba MMY-MAP0724HT6UL, Service Manual

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2. Outdoor
fan control 1. Cooling fan control
1) Outdoor fan speed (mode) is controlled on the basis of measurements provided by
the Pd pressure sensor.
2) For a specified period after the start of cooling operation, the header outdoor unit
controls outdoor fan speed (mode) on the basis of measurements provided by the
Pd pressure sensor. Follower units, on the other hand, control outdoor fan speed
(mode) on the basis of measurements provided by the TE1 temperature sensor.
* Available control modes are 0 (at rest) to 63.
• The fan speed
corresponding to the highest
mode varies with the HP
capacity of the outdoor unit.
2. Heating fan control
1) Outdoor fan speed (mode) is controlled on the basis of measurements provided by
the TE1 temperature sensor.
2) If TE1 > 77°F (25°C) is continuously detected for 8 minutes, the fan may be turned
off. However, this condition is the same as normal thermo OFF, so that fan
operation will be restarted.
3) For a specified period after air conditioner startup and during defrosting, this
control is disabled.
4) When refrigerant is in extremely short supply, this control may cause the air
conditioner to be repeatedly turned on and off.
• The fan speed
corresponding to the highest
mode varies with the HP
capacity of the outdoor unit.
3. Control while follower unit at rest
The fan is operated at mode 1 to prevent the accumulation of refrigerant inside the
outdoor heat exchanger.
3. Capacity
control 1) The compressors of the header and follower units are controlled on the basis of
capacity demand issued by indoor controllers.
2) The two or three compressors featured in an outdoor unit operate on a rotational
basis, so that, every time they come to a stop, their order of startup changes.
3) Where two or more follower units are connected, every time the system goes
thermo OFF or all the compressors featured in the follower units come to a stop,
the priority startup order of the follower units changes, as they are also subject to
rotational operation.
Item Description of operation, numerical data, and other information Remarks
Pd
pressure
[Highest mode]
[Current mode + 1]
(Mode raised as rapidly
as every second)
[Current mode + 1]/50 seconds
[Hold]
[Current mode + 1]/75 seconds
(Mode raised up to 13)
(Mode 1 to highest)
Mode being raised: mode 0 → 1
[Current mode - 1]/50 seconds
Mode being lowered:
Highest mode - 1 → 1
Interval control
[Mode [0]: 180 seconds
Mode [1]: 30 seconds]
[Current mode - 1]
(Mode lowered as rapidly as
every two seconds)
(down to mode 0)
TE1 temperature
°F (°C)
Zone A: Lowest mode, timer count for forced compressor shutdown
Zone B: -2/15 seconds (down to lowest mode)
Zone C: -1/15 seconds (down to lowest mode)
Zone D: Hold (staying at current mode)
Zone E: +1/15 seconds (up to highest mode)
Zone F: Highest mode