Carrier 42QHF009DS Service Manual page 47

(3) The louver operates same as in cooling mode.
(4) Auto fan in fan-only mode acts as follow:
For Console, A5 Duct：
When T1-24≤27℃, transfer high to medium speed,
When T1≤25℃, transfer medium speed to low.
When T1>25.5℃, transfer low to medium speed,
When T1>27.5℃, transfer medium speed to high.
For the other types：
When T1-TA≤3℃, transfer high to medium speed,
When T1-TA≤1℃, transfer medium speed to low.
When T1-TA >1℃, transfer low to medium speed,
When T1-TA >4℃, transfer medium speed to high.
For Four-way cassette (compact)
For A2
four-way cassette (compact)&A5 Duct：
(5) PTC function and sleep mode are invalid
11.7.2 Cooling mode
11.7.2.1 Compressor running rules
The compressor will run at corresponding frequency according to the gross amendatory capacity demand.
Frequency
T1
27.5
High
27
25.5
25
：TA=23
TA=24
COOL_F0 COOL_F1
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Medium
Low
......
COOL_F2 COOL_F15 COOL_F16