McQuay MWM - Sequential Board (SQ2.0)

MCQUAY Service Guide Book Controller Configuration
28
5.3 Sequential Board (SQ2.0)
Dip switch setting of sequential controller are as
the following:
Main Board SQ2.0
1. Models Selection
Model
Dip
switch 1
Dip
switch 2
a. No heater Off Off
b. 1 heater On Off
c. 2 heater On/Off On
Where n = no. of compressor(s)
Postfix no. = no. of heater(s)
2. Stage Differential Temperature
Differential temperature is the temperature
difference between turning on or off a compressor
to another compressor in thermostat cycle.
The stage differential temperature can be
selected from the range shown below:
Dip switch 3 Dip switch 4
a. Default Off Off
b. 0.5°C On Off
c. 1.0°C Off On
d. 1.5°C On On
Note: 1.5°C only valid for 2 and 3 compressors
model. For 4 compressors model, maximum
allowed is 1.0°C.
The default differential temperature is base on
number of compressor model, the setting is as
below:
Model Diff. Temperature
1 compressor Not. Applicable
2 compressors 1.5°C
3 compressors 1.0°C
4 compressors 0.5°C
3. Operating Modes
The system has 4 operating modes to select with
respect to each model selection:
Model Auto Cool Heat Fan Dip
switch
5
SQCn - X - X Off
SQHnh - X X X Off
SQHnh X X X X On
Where x denotes modes available
n = no. of compressor(s)
h = no. of heater(s)
4. Hot Keep Option
Dip switch 6
a. Fan off Off
b. Fan on On
5. Last Memory Functions
The power up settings for either with or without
the last memory Backup is based on the J_LST
setting.
J_LST Setting
a. Last memory Backup J_LST Plugged
b. W/o last memory Backup J_LST Removed
*For SQ1.0, the jumper is JH1.