Carrier 42QZA009DS-1 Service Manual page 36

While A,B,C...means different fan speed of outdoor unit.
8.4.2.2 Indoor fan running rules
For all models:
In cooling mode, indoor fan runs all the time and the speed can be selected as high, medium, low and auto.
When the compressor is running, the indoor fan is controlled as below:
The auto fan acts as below rules:
8.4.2.3 Evaporator low temperature T2 protection
For all models: When T2<4℃ for 250s or T2<0℃ , the indoor has no capacity demand and resume till
T2>8℃
T4
B
C
D
Setting fan
T1-Td ℃(° F)
speed
A
H
B
C
D
M
E
F
G
L
H
I
T1-Td
a
b
c
d
e
A+
A
E
F
G
H
I
Actual fan speed
H+(H+=H+G)
H（=H）
H-（H-=H-G)
M+(M+=M+Z)
M(M=M)
M-(M-=M-Z)
L+(L+=L+D)
L(L=L)
L-(L-=L-D)
H
(H-L)*0.75+L
(H-L)*0.5+L
(H-L)*0.25+L
L
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