Defrost Control - Carrier 38VMH-1P Service Manual

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Defrost Control

The outdoor unit activates defrosting operation by T3 and accumulative heating time after the latest defrosting.
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 Outdoor fan will run at step level W2 to prevent abnormal increase in high pressure value. This protection is shown as below.
Component
Compressor
Outdoor unit fan
Four way valve (ST1)
EEV
Fast oil return (SV4)
Hot gas bypass valve (SV5)
Spraying liquid valve (SV6)
Crankcase heater
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Table 32 —Defrosting Operation
Before Defrosting Operation
Current value
→30 Hz for 10 seconds
Normal control
ON
Current opening → 480 Pls
Normal control
OFF
Discharge temperature protection control
-
Table 33 —Stop Control
Cooling Operation
OFF
W7 step level for 30 seconds, then OFF
OFF
300 Pls
ON for two minutes, then OFF
OFF
OFF
ON if T4 ≤ 37°F with compressor stopped for more than three hours, or powered on for the first time, else OFF
Defrosting Operation
30 Hz for 30 seconds → Target
frequency for defrosting operation
(58 Hz for 38VMB036HDS3-1,66 Hz for
38VMB048, 060HDS3-1)
*1
ON for ten seconds, then OFF
ON for ten seconds, switch to OFF
480 Pls
OFF
Defrosting time reaches ten minutes
or T3 ≥ 54°F for one minute, or T3 ≥
68°F
Thermo-off standby: ON
Stop: ON for 15 seconds, then OFF
30
After Defrosting Operation
→30 Hz for 55 seconds, then adjusts to
normal control
OFF for 45 seconds, then normal control
OFF for 45 seconds, then switch to ON
300 Pls for four minutes, then normal control
Bypass control
six minutes
Heating Operation
A210271