Sequence Of Operation - Friedrich CEW18B33A Service Manual

Sequence of Operation

Main function
NOTES:
RT------Room Temperature.
IC------Indoor CoilTemperature.
ST------indoor Set Temperature.
OC---Outdoor Coil Temperature.
CRT---Compensated Room Temperature
1. Cooling mode
In the cooling mode, COOL indicator is ON, the set temperature and fan speed could be changed or adjusted.
a. When RT-ST≥ 1.8°F the compressor operates if there is not any protection or failure happened.
b. When RT-ST< 1.8°F the compressor stops, and fan motor keeps operation continuous.
c. When 1.8°F ≤RT-ST<1.8°F the compressor keeps former status.
1.1 Indoor fan motor control
1.1.1 Indoor fan motor can be controlled by Auto, Low, Med and High speed.
1.1.2 Indoor fan motor Auto control as below:
a) In cooling mode
b) While
c) If T= 3.6°F, in medium speed
d )If T≥7.2°F , in high speed
e) If 3.6°F <
at Low speed, it will change to Med speed automatically.
f) If 0°F ≤ T < 3.6°F, , The fan motor operates at original speed while it was set in Low or Med mode. If
original at High speed, it will change to Med automatically.
g) When fan speed changes due to the temperature variation, it could be changed only by sequence as High,
Med to Low speed or Low, Med to High speed, and each status will keep at least 2 minutes.
7.2
3.6
°
0
2. Dry mode
While selected to Dry mode, AC works at set temperature to 44.6°F for 3 minutes. After that the set temperature change to be
RT 3.6°F, the compressor works as cooling mode, and indoor fan motor operates at low speed.
The fan speed can not be changed while in dry mode, but the air direction can be adjusted.
14
OPERATION
T=RT-ST
T<0°F, operates in low speed;
T < 7.2°F , The fan motor runs at original speed while it was set in High or Med mode. If original
Temperature drop
°
F
High speed
°
F
Medium Speed
F
Low Speed
Auto fan speed in cooling mode
Temperature Rise
7.2°F
3.6° F