McQuay MDS 100B

Service Manual SM-MDS_(ii) 9
Fan Speed
Control
Outdoor fan speed control (cooling mode)
Outdoor fan speed control (heating mode)
Protection
Devices
MDS system has several sensor and pressure switch for protection purpose:
 Discharge pressure protection (switch)
 Suction pressure protection (sensor)
 Discharge temperature protection for Digital Scroll Compressor
 Compressor overload protection
 Fan motor overload protection
Others
For Fix Scroll Compressor:
 Minimum 3 minutes of start-up delay protection is available.
For Digital Scroll Compressor:
 When digital compressor overloaded or discharge pressure too high, system will stop
the outdoor for 3 minutes. System error will declare when outdoor unit stops for 3 times
within 1 hour.
 TH1 ≤ 105ºC – outdoor unit operates normally.
 TH1 ≥ 130ºC – outdoor unit forced to stop.
 105ºC ≤ TH1 ≤ 130ºC for 2 minutes, outdoor unit enter protection mode.
2