Carrier 38QUS012D8S Service Manual page 102

1.3.2.3 Evaporator Low Temperature T2 Protection.
---T2<0℃, the compressor stops and restarts only when T2≥5℃.
---0℃≤T2<4℃, the compressor frequency is limited and decreases to a lower level
---4℃≤T2<7℃, the compressor maintains its current frequency.
---T2>7℃, the compressor frequency is not limited.
1.3.2.4 High Condenser Coil Temperature Protection
1.3.3 Heating Mode
1.3.3.1 Outdoor Fan Running Guidelines
18K
Fan speed is regulated according to T4 and compressor frequency.
Frequency linkage area:
Electrical Control System
18K
T4
Frequency linkage area
A
A+
24~60K
T3
Off
Decrease
Hold
Resume
Electrical Control Function
100