Mitsubishi Electric PUHY-RP200, Service Handbook

Page: 105 / 306

[
VII
Control ]
- 96 -
HWE10130 GB
-5- Bypass Control
Bypass solenoid valves (SV1(a,b)), which bypass the high- and low- pressure sides, perform the following functions.
(1) Bypass solenoid valve (SV1a) (ON = Open)
(2) Bypass solenoid valve (SV1b) (ON = Open)
Operation
SV1a
ON OFF
At 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 OFF
After the operation has stopped Always OFF
During defrost operation Always ON
During refrigerant oil recovery SV1a turns off during refrigerant oil recovery that takes place after a low-
frequency operation (both in the cooling and heating modes).
When the low pressure (63LS) drops SV1a turns on if the low pressure
(63LS) drops below 0.23 MPa while
the compressor is operating at the
minimum frequency.
SV1a turns off if the low pressure
(63LS) reaches 0.38 MPa or above.
Operation
SV1b
ON OFF
At compressor startup ON for 4 minutes.
After the restoration of thermo or 3 minutes
after restart
ON for 4 minutes.
During cooling mode and when the com-
pressor is not in operation
SV1b turns on for three minutes, and turns on when the formula LPS -
LPS ≤ 0.2 MPa is satisfied.
During heating mode and when the com-
pressor is not in operation
Always OFF
After the operation has stopped SV1b turns on for three minutes, and turns on when the formula LPS -
LPS ≤ 0.2 MPa is satisfied.
During defrost operation Always ON
During refrigerant oil recovery SV1a turns off during refrigerant oil recovery that takes place after a low-
frequency operation (both in the cooling and heating modes).
When the low pressure (63LS) drops SV1a turns on if the low pressure
(63LS) drops below 0.23 MPa while
the compressor is operating at the
minimum frequency.
SV1a turns off if the low pressure
(63LS) reaches 0.38 MPa or above.