Refrigerant Bypass Control - Mitsubishi Electric PUHY-P250YNW-A Service Handbook

[5-2 Outdoor Unit Control ]
5-2-5

Refrigerant 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), (SV2) (ON = Open), (SV9) (ON = Open)
Operation
When starting-up the compressor of each
outdoor unit
After the restoration of thermo or 20 sec-
onds after restart
During cooling operation with the compres-
sor stopped
After the operation has stopped
During compressor operation at Fmin fre-
quency in the cooling mode and when the
low pressure (63LS) drops (three or more
minutes after compressor startup)
When high pressure (63HS1) rises
Operation
At startup
Others
Operation
10
- chapter 5
When low pressure (63LS) drops
below 0.23 MPa [33 psi].
When 63HS1 exceeds
3.62 MPa [525 psi]
When TH7<= -20, SV2 stays on for
5 minutes after startup or until the
condition 63HS < 1.96 MPa (284
-
SV1a
ON
ON for 4 minutes.
ON for 4 minutes.
Always ON.
Exception: OFF when 63HS1-63LS is 0.2 MPa [29 psi] or less
ON for 3 minutes.
Exception: OFF when 63HS1-63LS is 0.2 MPa [29 psi] or less
ON
psi) is met
Always OFF
ON
Always OFF
OFF
When low pressure (63LS) ex-
ceeds 0.38 MPa [55 psi].
When 63HS1 is 3.43MPa [497 psi]
or below in 30 seconds
SV2
OFF
Other than on the left
SV9
OFF
BS_05_C