McQuay MDS 150B - Page 90

84 Service Manual SM-MDS_(ii)
Ambient temperature beyond limit
Error Code: F7, 27 (For MC301), ER59 (For MDS-M PCB)
Check the ambient
temperature, is it out
of specification?
Contact contractors for advice as
condition is not suitable for the unit
to operate
NO
YES
Check the surrounding of
units. Any obstacle that
blocks the air movement?
YES
NO
Replace PCB.
Turn off the unit
Check the resistance
of sensor TH8, is it
within specification?
Refer Appendix 7.5
NO
Replace sensor and restart the
system
YES
Ensure no obstacle around the unit
and conduct inspection on coil and
filter
6