Carrier 38VMA Series, Service Manual, Page: 30 / 112

a. Cooling Fan Control
Table 18 -
Cooling Fan Control
Ambient temperature T4(
⁰
F) T4 < 32
32 ≤ T4 < 41 41 ≤ T4 < 50 50 ≤ T4 < 59 59 ≤ T4 < 68 68 ≤ T4 < 77 77 ≤ T4 < 86 T4 ≥ 86
Fan initial step 1 3 4 6 7 10 11 12
b. Fan Control Process
Figure 30 - Fan Control Process
NOTE:
When compressor ramps up, fan speed will be at the initial step for 90 seconds. Then the fan will be controlled per the fan
control process.
c. Heating Fan Control
Table 19 -
Heating Fan Control
Ambient Temperature T4
⁰
F T4 < 27 27
≤ T4 < 50
50
≤ T4 < 59
Fan Steps Step 13
Ambient temperature T4
⁰
F 59
≤ T4 < 68
68
≤ T4 < 77
77
≤ T4
Fan Steps
30