Service manual

11-9
CONTROL SYSTEM
SM HADDCI 1-A.2 GB
For cooling: Discharge super heat =CTT-CDT
For heating: Discharge super heat =CTT-ICT
(Where CDT=MAX(OCT,OMT
.Normal – No protection status is ON
.Stop-Decrease – System is in protection. Compressor frequency is not allowed to decrease
HzUp – System is in protection. Compressor frequency is increased by 3 Hz/min
11.7.6 Outdoor Coil Deicing Protection
11.7.6.1 Deicing Starting Conditions
1. For S/W 37V3 and lower ( For 453031000R Controller)
Deicing operation will start when either one of the following conditions exist
Deicing operation will start when either one of the following conditions exist:
 Case 1: OCT < OAT – 8 AND TLD > DI
 Case 2: OCT < OAT
max
– 12 AND TLD > 30 minutes.
 Case 3: OCT <-1 AND TLD> 100 mnutes.
 Case 4: OCT is Invalid AND TLD > DI
 Case 5: NLOAD = 0 AND OCT < OAT - 8
 Case 6: OCT<-19 AND TLD>60min:
When OATmax >0 or OAT is invalid; then DST=8
When OATmax ≤0; then DST= round down (-0.8 * OATmax) + 8
OATmax calculation:
After compressor starts for 3 minutes, OATmax calculation is start.
The OATmax is the moving value of the Maximum OAT during the 1st 10mintues within last
30minutes
OCT – Outdoor Coil Temperature
OAT – Outdoor Air Temperature
TLD – Time from Last Deicing
DI – Deicing Interval (Time Interval Between Two Deicing)
Deicing interval time when compressor is first started in heat mode, is 10 minutes if OCT < -2, and
is 40 minutes in other cases.
Deicing interval time is changed (increased/ decreased in 10 minutes steps) as a function of deicing
time. If deicing time is shorter then former deicing time, the deicing interval time will be increased. If
deicing time is longer then former deicing time, the deicing interval time will be decreased.
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