McQuay MDS Series User Manual

62 Service Manual SM-MDS_(ii)
Error Code #6
Description
Possible causes
Cool/Heat
Sleep/Fan
Time/Dry
BLINKING
OFF
BLINKING
High/low pressure switch trip
78
 High pressure trip
- outdoor unit motor broken
- outdoor circulating air short (cooling)
- outdoor heat exchanger too dirty (cooling)
- outdoor ball valve not open
- indoor circulating air short (heating)
- indoor heat exchanger too dirty (heating)
- indoor unit filter web blocked (heating)
- indoor unit EXV not turn on properly (heating)
- too much refrigerant
- outdoor unit PCB high pressure output port malfunction
- pressure sensor broken
- pressure switch broken
 Low pressure trip
- 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
Error Code #7
Description
Possible causes
Cool/Heat
Sleep/Fan
Time/Dry
BLINKING
BLINKING
OFF
Compressor overload
77
 Digital compressor’s operating current too high, overload protector on
 Fixed compressor’s operating current too high, overload protector on
Error Code #8
Description
Possible causes
Cool/Heat
Sleep/Fan
Time/Dry
BLINKING
BLINKING
BLINKING
System failure
80
 High pressure malfunction occur 3 times within 1 hour
 Low pressure malfunction occur 3 times within 1 hour
 Too high discharge temperature occur once
 Compressor overload protector shut and occur 3 times
Error Code #9
Description
Possible causes
Cool/Heat
Sleep/Fan
Time/Dry
BLINKING
ON
ON
Others
 Examine outdoor unit for error code.
 Connect wired controller to the unit to retrieve exact error code.
6

McQuay MDS Series Specifications

General

Brand	McQuay
Model	MDS Series
Category	Compressor
Language	English