ICM Controls SC 1901 General instructions

1-Stage Cool
Non-Programmable
Hardwired
SC 1901
Non-Programmable Electronic Thermostat
Installation, Operation & Application Guide
For more information on our complete range of American-made
products – plus wiring diagrams, troubleshooting tips and more,
visit us at www.icmcontrols.com
• Controls Single Stage Cooling Systems
• Compatible with A/C Systems
• 30-Minute Power Loss Memory Retention
• For use with 24 VAC Systems

Table of Contents
Parts Diagram ............................................................................................................................. 1
Specifications .............................................................................................................................. 2
Important Safety Information ..................................................................................................... 2
Package Contents/Tools Required............................................................................................... 3
General Description..................................................................................................................... 3
To Remove Existing Thermostat ................................................................................................ 4
To Install Thermostat .................................................................................................................. 4
Replacing Wiring Labels .............................................................................................................. 5
Operation .................................................................................................................................... 6
A Quick Test................................................................................................................................ 7
Wiring Diagram............................................................................................................................ 8
Troubleshooting .......................................................................................................................... 9
CAUTION! : This thermostat should be installed by trained technicians only. Adhere to all local
and national codes. Disconnect all power to the system before installing, removing,
or cleaning.

1
Parts Diagram
Mode Switch Fan Switch
Celsius/
Fahrenheit
Jumper
Reset Button
Auto On
OffCool

2
Specications
Important Safety Information
Input:
• Voltage: 18-30 VAC
Output:
• Maximum: 1 amp per terminal (3 amp total for all terminals)
Temperature Ranges:
• Temperature control range: 45°F to 90°F (7°C to 32°C) Accuracy: ± 1°F (± 0.5°C)
• Differential range: 1°F to 3°F (0.5°C to 1.5°C) Accuracy: ± 1°F (± 0.5°C)
• System configurations: Single-stage cool
• Terminations: R, C, Y, G
• Note: This thermostat is designed for: Single stage
cooling systems. It will retain your setpoint
temperature in memory for up to 30 minutes
during a power outage.
SET
ROOM
DIFF
Temperature
differential setting
Room temperature
Room temperature
setpoint
• Always turn off the thermostat before installing, removing, cleaning, or servicing. Turn off the power at
the main power source by unscrewing fuse or switching off circuit breaker
• Do not switch to Cool if outside temperature is below 50°F (10°C); this could damage your A/C system
and cause injury
• Do not install on voltages higher than 30 VAC
• All wiring must conform to local and national building and electrical codes and ordinances
• While cleaning, do not get soap directly on thermostat switches or LCD readout; only use a damp cloth
with a mild soap to wipe the outside of the thermostat cover

3
General Description
Package Contents/Tools Required
• The SimpleComfort®1901 thermostat is a hardwired, digital, mercury-free, non-programmable,
electronic thermostat
• Compatible with single-stage cooling systems
• Built-in Compressor Protection for air conditioners; to protect the A/C’s compressor, there is a 5-minute
delay between the system turning off and the A/C starting
• 30 minute power loss memory retention
Package includes: SimpleComfort®1901 non-programmable thermostat on base, thermostat cover, wiring
labels, screws and wall anchors, Installation, Operation and Application Guide
Tools required for installation: Drill with 3/16” bit, hammer, screwdriver

4
ELECTRICAL SHOCK HAZARD – Turn off power at the main service panel by removing the fuse
or switching the appropriate circuit breaker to the OFF position before removing the existing
thermostat.
1. Turn off power to the heating and cooling system by removing the fuse or switching off the
appropriate circuit breaker.
2. Remove cover of old thermostat. This should expose the wires.
3. Label the existing wires with the enclosed wire labels before removing wires (see Page 5).
4. After labeling wires, remove wires from wire terminals.
5. Remove existing thermostat base from wall.
6. Refer to the following section for instructions on how to install this thermostat.
To Install Thermostat
ELECTRICAL SHOCK HAZARD – Turn off power at the main service panel by removing the fuse
or switching the appropriate circuit breaker to the OFF position before removing the existing
thermostat.
IMPORTANT: Thermostat installation must conform to local and national building and electrical
codes and ordinances.
Note: Mount the thermostat about five feet above the floor. Do not mount the thermostat on an
outside wall, in direct sunlight, behind a door, or in an area affected by a vent or duct.
1. Turn off power to the cooling system. Move the Mode switch to Off .
2. To remove cover, insert and twist a coin or screwdriver in the slots on the sides of the thermostat.
3. Move the Fan switch to Auto.
4. Put thermostat base against the wall where you plan to mount it (Be sure wires will feed through the
wire opening in the base of the thermostat).
To Remove Existing Thermostat

5
Replacing Wiring Labels
To Install Thermostat (continued)
5. Mark the placement of the mounting holes.
6. Set thermostat base and cover away from working area.
7. Using a 3/16” drill bit, drill holes in the places you have marked for mounting.
8. Use a hammer to tap supplied anchors into mounting holes.
9. Align thermostat base with mounting holes and feed the control wires through wire opening.
10. Use supplied screws to mount thermostat base to wall.
CAUTION! : Be sure exposed portion of wires does not touch other wires.
11. Tighten screws on terminal block. Gently tug wire to be sure of proper connection. Double check that
each wire is connected to the proper terminal.
12. Seal hole for wires behind thermostat with non-flammable insulation or putty.
13. Set the temperature scale jumper to Fahrenheit or Celsius.
14. Replace cover on thermostat by snapping it in place.
15. Turn on power to the system at the main service panel.
Replace the old labels with the enclosed new labels:
Old New Type
F, G G Fan control relay
Cooling control
Transformer, common side
Transformer, hot side
C Y or C
If the C terminal is the cooling control, connect to Y terminal. If
it is the common side of the transformer, connect to C terminal

6
Operation
Setting the Room Temperature (Setpoint Temperature)
Step 1: Press the or button; the current temperature sepoint displays.
Step 2: Press the or button until the desired temperature sepoint displays.
The new temperature setting is automatically saved. After 5 seconds, the display returns to showing the
current room temperature.
Setting a New Temperature Differential
The default temperature differential is 1°. When your room temperature varies by 1°F, the thermostat
turns on your system. If you notice your system turning on and off too frequently, increase the
temperature differential.
Step 1: Remove cover and press the Reset button once.
Step 2: For the first 10 seconds of operation, the temperature differential is displayed.
Press the or button to select desired setting.
Changing Fahrenheit to Celsius
The temperature displays in degrees Fahrenheit as a factory set default. Follow these steps to change to
degrees Celsius:
Step 1: Remove the cover.
Step 2: Move the F/C jumper to the desired position, For Cusing the center pin as a common.
Step 3: Press the Reset button once and reinstall the cover.
Your LCD readout changes accordingly.
Starting the Thermostat
Step 1: Move the Fan switch into the Auto position.
Step 2: Move the Mode switch to Cool.

7
A Quick Test
CAUTION! : Do not switch system to cool if the outdoor temperature is below 50°F (10°C). This can
damage the air conditioning system and may cause personal injury.
Action: Set the Mode switch to Cool. Press the button until the temperature setting is 3°F below the
room temperature.
Result: The A/C system and fan should turn on.
Action: Set the Mode switch to Off.
Result: The A/C should turn off (There may be a fan delay).
Action: Set the Fan switch to On (continuous indoor fan operation).
Result: The blower fan should turn on.
Action: Set the Fan switch to Auto.
Result: The blower fan should turn off.
If the above test was successful, you have a proper installation.
If not: Double check that wires are securely connected and are connected to the proper terminals. Consult
the troubleshooting section (see Page 9).

8
Wiring Diagrams
Cooling Only
4-Wire, Single Transformer
24 VAC T
H
E
R
M
O
S
T
A
T
R
C
Y
G
120 VAC
HOT
Transformer
Cooling
Only
Fan
Control