McQuay PDAA Installation & Maintenance Data page 23

Cool Dry Mode
Select the Cool Dry Mode when the standard Cool
Mode does not provide sufficient dehumidification. In
Cool Dry Mode, the unit must run in Cool Mode for 12
minutes or until the temperature differential between
the room temperature and the set point is less than
2°F. This will also occur after a Cold Start or a Mode
change from Cool to Cool Dry. During this time, the
fan will operate in the Mode and Speed selected.
Until one or both of the above conditions are met,
the control will determine which Dry Mode (Zone) is
initiated based on the temperature differential between
the room temperature (Tr) and the temperature set
point (Ts):
Note: Cool Dry is not available with Sleep Function.
Figure 31. if Tr - Ts > 4°F, operation will be in Zone A
Figure 32. if 2°F < Tr - Ts < 4°F, operation will be in
Zone B
Figure 33. if 0°F < Ts - Ts < 2°F, operation will be in
Zone C
Figure 34. if Ts - Tr > 5°F, operation will be in Zone D
The other temperature ranges are dead bands for zone
stability.
Figure 31. Zone A
Compressor
On
Off
Low Fan
On
Off
* = Zone Determination Time
Figure 32. Zone B
On
Compressor
Off
8 mins.
On
Low Fan
Off
30 secs.
t
t
*
12 mins.
t
4 mins.
t
30 secs.
Figure 33. Zone C
On
Compressor
Off
6 mins.
On
Low Fan
Off
30 secs.
*
= Zone Determination Time
Figure 34. Zone D
On
Fan
Off
On
Compressor
Off
* = Zone Determination Time
IM 934-2 Applied PDAA/PDHA / Page 23 of 44
6 mins.
30 secs.
*
t
* t
12 mins.
t
t