Carrier 38VMA Series Service Manual page 32

Table 23 - Indoor Unit Operation
Status
Thermal ON
OFF
Thermal OFF
NOTE:
1. First, oil return operation will occur after 140 min from turning the power on to the system.
Oil Return Operation in Heating mode
Table 24 -
Next, oil return operation will occur after 8 hours of cumulative compressor operation time.
2.
Outdoor Unit Component
Compressor
Outdoor unit fan (FAN A)
Outdoor unit fan (FAN B)
Four way valve (ST1)
Electronic expansion valve (EXV A)
Electronic expansion valve (EXV B)
Electronic expansion valve (EXV C)
Solenoid valve (SV4)
Solenoid valve (SV7)
Table 25 - Indoor Unit Operation
Ending conditions
Status
Thermal ON
OFF
Thermal OFF
NOTES:
1. Oil return operation will occur after 140 min from turning the power on to the system.
Table 26 - Defrost Operation
2. Next, oil return operation will occur after 8 hours of cumulative compressor operation time.
Outdoor Unit Component
Compressor
Outdoor unit fan (FAN A)
Outdoor unit fan (FAN B)
Four way valve (ST1)
Electronic expansion valve (EXV A)
Electronic expansion valve (EXV B)
Electronic expansion valve (EXV C)
Solenoid valve (SV4)
Solenoid valve (SV7)
Ending conditions
Fan
ON
OFF
OFF
Pre Oil Return Operation
22 Hz + 20 Hz
Normal control
Normal control
ON
Normal control
Normal control
0P
Normal control
Normal control
75 seconds
Fan
ON
OFF
OFF
Pre Defrost Operation
30Hz + 28Hz
Normal control
Normal control
ON
Normal control
Normal control
0P
Normal control
Normal control
75 seconds
Oil Return Operation
High pressure control
High pressure control
OFF
480P
480P
80P
Normal control
Normal control
120 seconds
Defrost Operation
78Hz + 76Hz
OFF
OFF
OFF
480P
480P
480P
Normal control
Normal control
T3 > 59⁰F，or T > 600 seconds，
or T4 < 32⁰F, or T3 > 50⁰F 120 seconds
Electronic Expansion Valve
ON
300P
300P
Post Oil Return Operation
22 Hz + 20 Hz
Normal control
Normal control
ON
Normal control
Normal control
0P
Normal control
Normal control
55 seconds
Electronic Expansion Valve
480P
480P
480P
Post Defrost Operation
30Hz + 28Hz
Normal control
Normal control
ON
Normal control
Normal control
0P
Normal control
Normal control
10 seconds
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