Oil Return Operation - Carrier 38VMH-1P Service Manual

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Oil Return Operation

When cumulative compressor operating time exceeds eight hours, the outdoor unit starts oil return operation.
Component
Compressor
Outdoor unit fan
Four way valve (ST1)
EEV
Fast oil return (SV4)
Hot gas bypass valve (SV5)
Spraying liquid valve (SV6)
Ending conditions
Component
Compressor
Outdoor unit fan
Four way valve (ST1)
EEV
Fast oil return (SV4)
Hot gas bypass valve (SV5)
Spraying liquid valve (SV6)
Ending conditions
*1 Fan control for oil return in heating mode.
If T4 ≥ 59°F, outdoor fan step is W2. Otherwise, follow the logic below.
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Table 30 —Oil Return in Cooling Mode
Before Oil Return Operation
Normal control
Normal control
OFF
Normal control
Normal control
OFF
Discharge temperature protection control
-
Table 31 —Oil Return in Heating Mode
Before Oil Return Operation
Current value
→30 Hz for two seconds
Normal control
ON
Current opening→300P
Normal control
OFF
Discharge temperature protection control
-
Oil Return
Target frequency for oil return (58Hz
for 38VMB036HDS3-1,66Hz for
38VMB048, 060HDS3-1)
300 Pls
five minutes
Oil Return
30Hz for 30sec→
Target frequency for oil return (58Hz
for 38VMB036HDS3-1, 66Hz for
38VMB048, 060HDS3-1)
*1
Low pressure control
OFF
300 Pls
OFF
five minutes
A210270
29
After Oil Return Operation
Normal control
Normal control
-
After Oil Return Operation
→30 Hz for 55 seconds, then normal
control
Normal control
OFF for 45 seconds, then switch to ON
300 Pls
Bypass control
six minutes