CoolAutomation SMT-131, Manual, Page: 5 / 18

Page 5
Take care to ensure excess wiring is not trapped between the cases half’s when closing - push
excess wires into the wall cavity. Never press on the LCD when closing the SMT-131 as it may crack.
Always press on the SMT-131 plastic case only.
DIP Switch Settings
Switch Function On Off
Sw1 Indoor Fan Mode 3 Fan Speed 1 Fan Speed
Sw2 Equipment Type Heat Pump Heat Cool
Sw3 HP Mode (Sw2= ON)
HC Mode (Sw2=OFF) Rev Valve Heat (B)
HE
– Fan With Heat
Rev Valve Cool (O)
HG
– No Fan In Heat
Sw4 2 / 4 pipe mode 2 pipe mode 4 pipe Mode
Sw5 Comp Protection Delay 5 Min Anti Cycle Immediate Comp start
Sw6 Klixon (Ricardo) Mode On Off
Sw7 Ventilation Mode Permitted Not Permitted
Sw8 Door Station (Optional) Fitted Door Station Not Used
Note: The SMT-131 reads the switch settings on power up only. If you change any DIP switch
settings you must power cycle before these changes will take effect.
It is expected that only qualified people will make adjustment to these dip switch settings.
Knowledge of the HVAC system under the control of the SMT-131 is essential prior to making
adjustment to these DIP switch settings.
Caution
Incorrect adjustment of these DIP switch settings could cause HVAC equipment
damage. This would NOT be covered by warranty.
Wiring – HVAC Control
Terminal Designations
Terminal Function
C 24V Neutral
R 24V Active - This voltage is switched back through the relays
Hi Indoor Fan High Speed ( NOT Used in Single fan speed mode - Sw 1 = OFF)
Med Indoor Fan Medium Speed ( NOT Used in Single fan speed mode - Sw 1 = OFF)
Low Indoor Fan Low Speed (Used in single & three fan speed mode)
Y Compressor or Cool - (Based on Sw 2 setting)
W - O/B Reversing Valve or Heat - (Based on Sw 2 setting)
A1 – Cool 0-10V Output for Cooling (Typically used to control modulating valves)
A2 – Heat 0-10V Output for Heating (Typically used to control modulating valves)
A3 – Fan 0-10V Modulating Output for Indoor DC Fan
Com – 0V 0V terminal - Used for 0-10V, sensor or digital inputs ground reference
A Modbus Data A
B Modbus Data B
SI Remote temperature sensor input (Remote / average / Modbus data use)
DI Digital (Switched input) for forced un-occupied or initiate doorbell function
WC Window Contact - Forces SMT-131 OFF if window open > 5 min (Adjustable)
DS Door Switch – Monitors room door status for occupancy detection (see page 11)
PIR PIR (Movement sensor) input for occupancy detection (see page 11)