MXS Service Manual

Control Specification SiUS121736EA
99 Functions and Control
4.7.2 Freeze-up Protection Control for FDMQ Series
Outline During cooling operation, the signal sent from the indoor unit determines the frequency upper limit
and prevents the indoor heat exchanger from freezing.
Details When the freeze-up protection control starts, the compressor stops, the airflow rate is fixed to L tap,
and the drain pump turns ON. Conditions for starting and ending are as below.
Starting conditions
The freeze-up protection control starts when any of the following conditions is satisfied.
z The indoor heat exchanger temperature remains at A or lower for 1 minute.
z The accumulated time that the indoor heat exchanger temperature remains at B or lower
reaches 40 minutes.
Accumulated timer clearing condition
z The indoor heat exchanger temperature remains at C or higher for 20 minutes.
Ending condition
z The indoor heat exchanger temperature remains at D or higher for 10 minutes.
(°C) (°F)
A –5 23.0
B –1 30.2
C 439.2
D 744.6
D
A
B
C
Indoor heat
exchanger
temperature
The control starts.
The control starts.
The control ends
and the accumulated timer is cleared.
The accumulated timer is cleared.