Carrier 38QUS012D8S Service Manual page 104

1.3.3.3 Defrosting Control：
Conditions for defrosting:
----the unit enters the defrosting mode according to the value of T3 and T4 as well as the compressor
running time.
Defrost Stop Conditions:
If any one of the following conditions is satisfied, defrosting ends and the unit returns to heating mode.
----T3 rises above than TCDE1℃.
----T3 remains at TCDE2℃ or above for 80 seconds.
----The machine runs for 10 consecutive minutes in defrosting mode.
1.3.3.4 High Evaporator Coil Temperature T2 Protection:
Off: Compressor stops.
Decrease: Decreases the running frequency.
Hold: Maintains the current frequency.
Resume: No limitation is applied to frequency.
.
1.3.4 Auto-mode
You can choose this mode with the remote control and adjust to temperature to between 17-30.
In auto mode, the machine chooses cooling, heating or fan-only mode according to ΔT (ΔT =T1-Ts).
Electrical Control System
ΔT=T1-Ts
ΔT＞2℃
-2<ΔT≤2℃
ΔT≤-2℃
Electrical Control Function
Running mode
Cooling
Fan-only
Heating
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