Special Control - Carrier 38VMH-1P Service Manual

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Special Control

Component
Compressor
Outdoor unit fan
4-Way Valve (ST1)
EEV
Fast oil return (SV4)
Hot gas bypass valve (SV5)
Spraying liquid valve (SV6)
Ending conditions
SEQUENCE:
Sequence A: T5 ≥ 59°F and T4 ≥ 23°F, or T4 ≥ 37.4°F.
Sequence B: 23°F ≤ T4 < 37.4°F.
Sequence C: 5°F ≤ T4 < 23°F.
Take sequence A as an example, and assume that the target frequency is 50 Hz.
The compressor runs 33 Hz and 42 Hz for 60 seconds respectively, and goes to 50 Hz afterward.
If the target frequency is higher than 66 Hz, the ODU needs to operate at 33, 42, 56, 66 Hz respectively for one minute, or it directly
goes to the target frequency like the example above.
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Table 29 —Startup Control
Cooling Operation
Capacity demand control
W7 for twenty seconds, then control based
on frequency, T4, T5, and Tc
OFF
300 pls for three minutes after compressor
starts, then normal control
ON
OFF
OFF
According to target frequency and startup stage
Fig. 35 —Sequence for Startup Control
SV5 will open if heating frequency ≥ 50 Hz with startup manner A or B.
Heating Operation
Capacity demand control
Maximum speed referred to T4 and
frequency
ON
300 pls for three minutes when T4 ≥ 32°F
300 pls for 6minutes when T4 < 32°F
Then normal control
ON
*2
Bypass control
OFF
28
Remark
*1
Sequence A to C
Continuous time based on T4
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