CONTROL SYSTEM
12-6
SM PNXADCI 1-A.1 GB
When in auto cool heat mode unit will automatically select between cool and heat mode according
to the difference between actual room temperature and user set point temperature (∆T).
Unit will switch from cool to heat when compressor is off for 3 minutes, and ∆T < -3.
Unit will switch from heat to cool when compressor is off for 5 minutes, and ∆T < -3.
12.6 Dry Mode
As long as room temperature is higher then the set point, indoor fan will work in low speed and
compressor will work between 0 and MaxNLOADIF1C Hz.
When the room temperature is lower than the set point, compressor will be switched OFF and
indoor fan will cycle 3 minutes OFF, 1 minute ON.
12.7 Protections
There are 5 protection codes.
Normal (Norm) – unit operate normally.
Stop Rise (SR) – compressor frequency can not be raised but does not have to be decreased.
HzDown1 (D1) – Compressor frequency is reduced by Down1 Hz/min.
HzDown2 (D2) – Compressor frequency is reduced by Down2 Hz/min.
Stop Compressor (SC) – Compressor is stopped.
12.7.1 Indoor Coil Defrost Protection
ICT Trend ICT
Fast
Increasing
Increasing No change Decreasing
Increasing Fast
Increasing
ICT > 55
SC SC SC SC SC
53 < ICT ≤ 55
D1 D1 D2 D2 D2
49 < ICT ≤ 53
SR SR D1 D2 D2
47 < ICT ≤ 49
SR SR SR D1 D2
45 < ICT ≤ 47
Norm Norm SR SR D1
43 < ICT ≤ 45
Norm Norm Norm SR SR
ICT ≤ 43 Normal
12.7.3 Compressor over Heating Protection
Compressor temperature can be in one of 5 control zones (4 in protection, and 1 normal), according
to the following chart.
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