McQuay MDS Series User Manual

Service Manual SM-MDS_(ii) 65
FE
Master unit and slave
unit communication
malfunction
 Master unit and slave unit communication wire reversed
 Master unit and slave unit communication wire broken or loose
 Slave unit toggle switch set wrongly
 Master and slave unit PCB version conflict / different
79
H0
Digital compressor
overloaded
 Digital compressor operating current too high, overload protector OL4 on
77
H1
Fixed compressor 1
overloaded
 Fixed compressor 1 operating current too high, overload protector OL1 on
H2
Fixed compressor 2
overloaded
 Fixed compressor 2 operating current too high, overload protector OL2 on
H3
Fixed compressor 3
overloaded
 Fixed compressor 3 operating current too high, overload protector OL3 on
H4
High pressure too high
 Outdoor motor broken (cooling)
 Outdoor circulating air short-circuit (cooling)
 Outdoor heat exchanger too dirty (cooling)
 Outdoor ball valve not open
 Indoor circulating air short-circuit (heating)
 Indoor heat exchanger too dirty (heating)
 Indoor unit filter blocked by dirt (heating)
 Indoor EXV not on properly (heating)
 Refrigerant over charged
 Outdoor PCB high pressure output port abnormal
 Pressure sensor broken
 Pressure switch broken
78
H5
High pressure sensor
malfunction
 High pressure sensor communication wire broken
 Outdoor PCB HS port broken
74
H6
Discharge temperature
too high (TH1)
 Outdoor motor broken (cooling)
 Outdoor circulation air short-circuit (cooling)
 Outdoor heat exchanger too dirty (cooling)
 Outdoor EXV not on properly (heating)
 Indoor EXV not on properly (heating)
 Refrigerant leakage or insufficient
 Outdoor ball valve not open
78
L0
Super heat protecting
value too small
 Indoor motor not work when cooling
 Indoor EXV opening degree abnormal when cooling
 Outdoor motor not work when heating
 Outdoor EXV opening degree abnormal when heating
 Low pressure sensor abnormal
 Refrigerant over charged
86
L1
Low pressure too low
 Outdoor ball valve not open
 Outdoor heat exchanger efficiency too low when heating
 Outdoor motor run abnormally when heating
 Refrigerant leakage or insufficient
 Outdoor PCB low pressure output port abnormal
 Low pressure sensor broken
78
6

McQuay MDS Series Specifications

General

Brand	McQuay
Model	MDS Series
Category	Compressor
Language	English