Thermal Zone 12H47YIMI, Service Manual

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35
8.4.3.4 Defrost Mode
After extended use, frost may build up on the coils on the outdoor unit. The development
of frost can slow the rate of heat transfer which can cause many various problems such
as overloading the system. To prevent this, the system has an automatic defrost mode
according to the temperature T3, and also the compressor running time.
During the defrosting mode, the compressor keep running, indoor and outdoor motor will
stop, the operating symbol
“ ” will be displayed on the indoor panel.
If any one of the following items is satisfied, the defrosting will finish and the machine will
back to normal heating mode.
----T3 rises to be higher than TCDE 1.8
°
F.
----T3 keeps on being higher than TCDE 3.6
°
F for 80 seconds.
----The machine has run for 15 minutes in defrosting mode.
8.4.3.5 Evaporator temperature protection
Off: Compressor stops.
Decrease: Decrease the running frequency to the lower
level.
Hold: Keep the current frequency.
Resume: No limitation for frequency.
8.4.4 AUTO Mode
This mode can be chosen with remote controller and the setting temperature can be changed
between 62°F~86°C
In Auto mode, the unit will automatically choose between cooling, heating, or fan-only mode
according to the temperature
difference ΔT (ΔT = T1 – T
S
) on the auto-fan speed. If the
temperature changes enough to switch between heating and cooling mode, the compressor will
stop for 15 minutes first and then determine what mode to switch into according to ΔT.
Indoor fan will run at auto fan of the relevant mode.
The louver operates same as in relevant
mode.
Range Mode
ΔT > 3.6°F COOL
-3.6 °F < ΔT ≤ 3.6°F FAN
ΔT ≤ -3.6°F HEAT
TEstop
T2
Resume
Off
Decrease
TEdown
TEH2
Hold
TEstop
T2
Resume
Off
Decrease
TEdown
TEH2
Hold