Carrier High Wall Duct Free Split System 38MVC Service Manual page 24

Dry (Dehumidification) Mode
When more humidity control is desired, the Dry setting can be
selected. Lower humidity is achieved when the microprocessor
adjusts the indoor fan speed and compressor cycling by comparing
the room temperature (T) and the set point temperature (TS).
There are two different control algorithms:
Size 9k and 12 k units:
T = TS + 3.6 - - the compressor will run for 6 minutes and the
indoor fan will run at low speed. The compressor will be off for 4
minutes and the indoor fan will run in ultra low speed.
TS = T < TS + 3.6 - - The compressor will run for 5 minutes and the
indoor fan will run at low speed. The compressor will be off for 5
minutes and the indoor fan will run in ultra low speed.
T < TS - - The compressor will run for 4 minutes and the indoor
fan will run at low speed. The compressor will be off for 6 minutes
and the indoor fan will run in ultra low speed.
Size 18k and 24k units:
These units do not have ultra low speed.
dehumidification, the indoor fan runs at low speed and the
compressor cycles based on the difference between T and TS.
Manual Operation
The unit can be set for Forced Auto or Forced Cooling manually
by pushing the Manual button once or twice as shown below:
Push 3 Times Push Once
Remote Forced
mode
Fig. 33 – Manual Operation
When set for
Push Twice
Forced
auto cooling
A08116
Forced Auto (Emergency Operation)
Forced Auto option allows operation of the unit if the remote
control is lost or the batteries have expired. When the system is in
Forced Auto, it will run with a default set point of 75.2_F. While
in Forced Auto, the system will respond to signals from the remote
control.
Forced Cooling Operation
This option is used for diagnostic purposes. The system is forced
to run in cooling for 30 minutes.
After 30 minutes, the 9k and 12k systems will switch to Dry mode
with a default set point of 75.2_F. The 18k and 24k systems will
switch to Forced Auto mode. When the system is in Forced
Cooling mode, it will not respond to signals from the remote
control. The only way to exit the Forced Cooling mode is to push
the manual button once to switch the system to remote control
mode.
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