42
FORM 145.32-IOM5
ISSUE DATE: 04/08/2019
SECTION 2 – STARTUP AND OPERATION
Condensate Overflow Switch
A condensate overflow fault occurs when the conden-
sate overflow switch opens for the first time, as the
switch is connected to the onboard shutdown (SD) con-
tact. The compressor is shut down regardless of min-
imum runtime. The ASCD is initiated and the alarm
is tripped. The fan continues to operate in its current
state. The compressor re-energizes once the conden-
sate overflow switch closes, the ASCD has been satis-
fied, and a call for cooling is still present.
Operation
Compressor Operation
Compressor operation includes the following features:
1. Compressors are controlled by the Y1 through a
maximum of Y4 thermostat inputs.
As lead-lag function must be turned OFF,
Y1 input energizes the C1 output when
the compressor #1 ACSD is at 0 and all
refrigerant safety devices are closed (de-
fault 5 minutes).
2. The fan output for indoor fan operation energizes
with any cooling output after the indoor fan cool
on delay expires.
3. When the thermostat cooling inputs are lost and
the minimum runtime expires, the compressor
outputs stage off (the default is 3 minutes).
4. A 30 second interstate delay occurs when mul-
tiple stages are requested.
TABLE 26 -
COMPRESSOR CONTROL
CONTROL COMPRESSOR POWER
TYPE
EVAPORATOR
FAN %
Y1
1
Power
50%
Y2
2
Power
60%
Y3
2
Solenoid
75%
Y4
1
Solenoid
100%
IntelliSpeed
™
Supply Fan Control (8/10 Ton
Unit Only)
Setpoints and related data are shown in
Table 27 .
TABLE 27 -
SETPOINTS AND RELATED DATA
FAN CONTROL TYPE
FIXED
VARIABLE
Occupied, No Heat Or Cool %
Command
50%
0–100%
Occupied, One Stage of Cool %
Command
50%
50–100%
Occupied, Two Stage of Cool %
Command
60%
50–100%
Occupied, Three Stage of Cool
% Command
75%
50–100%
Occupied, Four Stage of Cool %
Command
100%
50–100%
Occupied, One Stage of Heat %
Command
0–100%
Occupied, Two Stage of Heat %
Command
0–100%
Occupied, Three Stage of Heat
% Command
0–100%
Economizer Minimum Position
0–100%
Economizer Minimum Position
for Low Speed Fan
0–100%
• The outputs have the following values:
• 24 VAC from fan on the unit control board
(UCB) to enable indoor VFD
• 2–10 VDC from VFD terminal on UCB to
control the speed of the indoor VFD
• The VFD operation has the following values:
2–10 VDC output from VFD terminal on UCB
operates the supply fan VFD proportional to the
minimum and maximum frequency settings of the
VFD (the defaults are 30–60hz)
• The supply fan only operation is as follows:
When there is no demand for heating or cooling,
to run, the supply fan operates at the percent out-
put of the No Heat or Cool % Command setpoint
• The cooling supply fan operation is as follows:
With a demand for cooling, the VFD operates at
the frequency relating to the setpoint Occupied, #
Stage of Cool % Command as defined under the
Indoor Fan setting menu on the SE controller.
