Mitsubishi Electric PUHY-(E)P300, Service Handbook

Page: 97 / 302

[
VII
Control ]
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HWE07010 GB
-5- Bypass Control
Bypass solenoid valves (SV1a), which bypass the high- and low- pressure sides, perform the following functions.
(1) Bypass solenoid valve (SV1a) (ON = Open), (SV9) (ON = Open)
Operation
SV1a
ON OFF
When each indoor unit compressor startup ON for 4 minutes.
After the restoration of thermo or 3 minutes
after restart
ON for 4 minutes.
During cooling or heating operation with the
compressor stopped
Always ON.
Exception: OFF when 63HS1-63LS is 0.2 MPa [29 psi] or less
After the operation has stopped ON for 3 minutes.
Exception: OFF when 63HS1-63LS is 0.2 MPa [29 psi] or less
During defrost operation ON
While the compressor is operating at the
minimum frequency and when the low pres-
sure (63LS) drops (3 or more minutes after
compressor startup)
When low pressure (63LS) drops
below 0.23 MPa [33 psi].
When low pressure (63LS) ex-
ceeds 0.38 MPa [55 psi].
When high pressure (63HS1) rises When 63HS1 exceeds
3.62 MPa [525 psi]
When 63HS1 is or below
3.43 MPa [497 psi] and 30 seconds
have passed
Operation
SV9
ON OFF
When high pressure (63HS1) rises during
the heating operation
When 63HS1 exceeds 3.50MPa
[507psi]
When 63HS1 is or below 2.70Mpa
[391psi]
When startup or resuming operation after a
defrost cycle
ON for 5 minutes and goes OFF
Others Always OFF