ICM Controls ICM326H User guide

ICM326H/ICM327H
Line Voltage Head Pressure Control
With built-in transformer
Optional heat pump override
For information on our complete range of American-made
products — plus wiring diagrams, troubleshooting tips
and more, visit us at www.icmcontrols.com
Application Guide

Table of Contents
Specications ........................................................................................... 1
Connections for ICM326H at 120 VAC ..................................................... 2
Connections for ICM326H at 208/240 VAC .............................................. 3
Connections for ICM327H at 480 VAC ..................................................... 4
Connecting the Probe .............................................................................. 5
Connections for Heat Pump Systems ...................................................... 6
Mode of Operation ................................................................................... 6
Setting the Cutout Speed ........................................................................ 7
Setting the Hard Start Time..................................................................... 8
Troubleshooting ....................................................................................... 9
Appendix A .............................................................................................. 10
Appendix B .............................................................................................. 10
ICM326H Typical Installation .................................................................... 11
ICM327H Typical Installation .................................................................... 12

• Line voltage: 120, 208/240, and 480 VAC
• Frequency: 50/60 Hz
• Output: 10 amp maximum, 100 mA minimum
• Operating temperature: -40° to +75°C
• Sensors: 10K ohms at 25°C
• Heat pump override: N.C. or N.O.
Note: A maximum of three sensors can be connected to the control
• Weight: 12 ounces (341 grams)
Note: The ICM326H and 327H should be applied to motors and equipment that
have been designated by their respective manufacturers as capable of
being speed controlled
• Mounting:
– Surface mount using (4) #8 screws (4.5”L X 3”W X 2”H)
– The ICM326H and 327H should be surface mounted to a clean metal, or other
thermally-conductive surface for maximum heat dissipation
– It is recommended that the ICM326H and 327H be mounted away from the
condenser exhaust air to maintain lower operating temperatures
ELECTRICAL SHOCK HAZARD – Installation of the ICM326H and ICM327H
shall be performed by trained technicians only. Adhere to all local and
national electric codes. Disconnect all power to the system before making
connections.
Specications
1

2
Connections for ICM326H at 120 VAC
1. Remove power from system.
2. Add wire from Line 1 wire to Line 1 terminal.
3. Cut Line 2 wire; afx motor side to Motor 2 terminal, and line side to Line 2
terminal.
4. Make probe (see Page 5) and heat pump (see Page 6) connections.
5. Verify wiring is correct.
6. Power up system and check operation.
120
Volts
PSC
Fan
Motor
Hard Start Knob
Cutout Speed Knob
Cut Original Wire
Run
Capacitor
Field Installed
Connection
MotorLine
2
Line
1

3
Connections for ICM326H at 208/240 VAC
1. Remove power from system.
2. Add wire from Line 1 wire to Line 1 terminal.
3. Cut Line 2 wire; afx motor side to Motor 2 terminal, and line side to Line 2
terminal.
4. Make probe (see Page 5) and heat pump (see Page 6) connections.
5. Verify wiring is correct.
6. Power up system and check operation.
PSC
Fan
Motor
Hard Start Knob
Cutout Speed Knob
Cut Original Wire
Run
Capacitor
Field Installed
Connection
208/240
Volts
MotorLine
2
Line
1

4
Connections for ICM327H at 480 VAC
1. Remove power from system.
2. Add wire from Line 1 wire to Line 1 terminal.
3. Cut Line 2 wire; afx motor side to Motor 2 terminal, and line side to Line 2
terminal.
4. Make probe (see Page 5) and heat pump (see Page 6) connections.
5. Verify wiring is correct.
6. Power up system and check operation.
PSC
Fan
Motor
Hard Start Knob
Cutout Speed Knob
Cut Original Wire
Run
Capacitor
Field Installed
Connection
480
Volts
MotorLine
2
Line
1

5
Connecting the Probe
1. Install the temperature probe several bends into the
condenser. It can be attached to the U-bend or placed
between the ns in the upper 1/3 of the condenser (see
Pages 10-12 for more information).
Note: The response of the system can be ne tuned by
repositioning the probe.
2. Connect the two wires from the sensor to the terminal
block where it is marked PROBE S1. If additional probes are necessary for
multiple refrigerant circuits, they may be attached to terminals marked PROBE
S2 and PROBE S3.
Note:
The control will respond to the probe that senses the highest
temperature.
3. For non-heat pump applications, the heat pump select jumper must be in the
Default (N.O.) position, and the HP terminals must be left unconnected.
4. Set the Cutout Speed knob (see Page 7), and the Hard Start Time knob (see
Page 8) to the appropriate positions for the type of motor you have.
Example
Heat Pump Select Jumper
Default Position
Probe S1
Probe S2
Probe S3
HP
Temperature
Probe

6
Normal Function
With probe temperatures above 100°F, the control applies full voltage to the motor.
The green light is illuminated (full speed LED).
With probe temperatures between 70°F and 100°F, the motor speed is proportional
to the probe temperature. The yellow light is illuminated (variable speed LED).
When the motor starts at temperatures between 70°F and 100°F, it will hard start
for the length of time dictated by the setting of the Hard Start knob. After the hard
start time has elapsed, the motor speed is controlled by the probe temperature.
Connections for Heat Pump Systems
1. The heat pump terminals accept the line voltage signal from the reversing valve
holding coil. Make a parallel connection from the reversing valve to HP terminals.
2. If the heat pump is in the Heating mode and the reversing valve is
energized, then the Heat Pump Select jumper must be in the
Default (N.O.) position.
3. If the heat pump is in the Heating mode and the reversing valve is
not energized, then the Heat Pump Select jumper must be in the
N.C. position.
Heat Pump Select Jumper
Default Position
Probe S1
Probe S2
Probe S3
HP
Temperature
Probe
Connect Parallel
to Reversing
Valve
N.O.
N.C.
Mode of Operation

Cutout Speed Knob
7
The Cutout Speed knob adjusts the motor voltage range that determines the RPM
level of the condenser fan. Set the Cutout Speed knob according to the type of
motor you have.
Sleeve Bearing Motors:
Set the Cutout Speed knob to the middle of the sleeve bearing range. In this range,
the motor can run down approximately 40-50% of the full line voltage, which allows
sufcient RPMs for cooling and lubrication.
CAUTION! : With sleeve bearing motors, it is important not to adjust
outside the sleeve bearing range or bearing failure may result.
Ball Bearing Motors:
Set the Cutout Speed knob to the MIN position in the ball bearing range. This
position offers the greatest range of speed control. At the MIN setting the motor
can run down to approximately 20-30% of the full line voltage.
Note:
After starting at the
recommended settings for
either sleeve or ball bearing
motors, you can tune the
cutout speed to achieve the
desired results.
Setting the Cutout Speed
As the temperature being sensed decreases, the output voltage decreases. The
output voltage may decrease to the determined cutout speed. Upon reaching the
Cutout Speed knob setting, the output voltage will go to zero volts.
System restart occurs when the temperature exceeds 70°F.
With probe temperatures below 70°F, the motor remains off. The green light and the
yellow light are off.
Heat Pump Bypass Operation
Heat Pump Bypass mode runs the fan at full speed when the system is operating in
Heat mode. This moves as much air across the condenser coil as possible.
If the Heat Pump Select jumper is in the N.O. position and line voltage is present at
the HP terminals, the motor will be brought to full speed.
If the Heat Pump Select jumper is in the N.C. position and line voltage is not present
at the HP terminals, the motor will be brought to full speed.
A separate relay is not needed.
Sleeve
Bearing
Range
Ball
Bearing
Range
MIN
MAX

8
During the Hard Start mode, full voltage is applied to the motor during startup to
overcome windmilling and to lubricate the bearings.
The position of the Hard Start knob determines the time period of the Hard Start
mode. The knob can be adjusted between 0.1 second and approximately 5 seconds.
Set the Hard Start knob according to the type of motor you have. If you have a ball
bearing motor, set the Hard Start knob to the MIN position. If you have a sleeve
bearing motor, set the Hard Start knob to the middle of the sleeve bearing range.
After you begin at the recommended setting,
you can ne tune the hard start time within the
recommended range for the type of motor you
have.
It is recommended that you use the minimum
possible hard start time to avoid blowing too
much cold air over the condenser.
Hard Start mode is activated when line voltage
is applied (or disconnected and reapplied). The
Hard Start mode applies full voltage to the
motor for the set time period. Afterwards, the
motor speed is dictated by the temperature
sensor(s).
Setting the Hard Start Time
Ball
Bearing
Range
Sleeve
Bearing
Range
MAX
MIN
Hard Start Knob

9
SYMPTOM REMEDY
Unit fails to
start
The sensor may not be connected or it is defective.
With the probe disconnected, use an ohmmeter to measure
the resistance between the probe wires. It should match the
chart in Appendix B. If you read an OPEN or SHORT, replace the
sensor.
Fuse and/or
circuit blows
The unit has been mis-wired and may be permanently
damaged.
The fan cycles
from full ON to
full OFF with
little or no
modulation
First turn OFF the power. Reapply power and conrm hard
start operation. Reduce the hard start period to the minimum
setting required to accelerate the fan. Excessive hard starting
causes large pressure drops by moving too much cold air over
the condenser.
Check position of heat pump select jumper (see Pages 6-7).
Should the cycling persist, move the probe up several bends
into the condenser to increase the sensitivity to condensing
temperature.
Fine tune cutout adjustment.
The fan does
not come on
at all
Measure the line voltage between LINE 1 and LINE 2 to conrm
that the line voltage is present.
Remove the thermistor probe from the terminal block and
measure its resistance at ambient temperature. Compare your
reading at the appropriate temperature in Appendix B to see
if the actual resistance approximates the listed value. Next,
hold the probe in your hand and conrm that the resistance
decreases.
Place a temporary jumper across the S2 or S3 terminals. Fan
should run at full speed. If it does, recheck probe connection
and verify probe is operating correctly.
The high
pressure switch
trips off
Move the probe farther into the condenser where the
temperature is higher. This will produce a higher fan RPM and
decrease the head pressure.
Fine adjust the cutout and hard start settings.
Troubleshooting

10
Mounting a sensor into the condenser
versus mounting it on the liquid line
When a sensor is mounted into the condenser, the control responds more rapidly
to changes in head pressure than when it is mounted on the liquid line. This is
especially true for high efciency condensers.
When the sensor is mounted on the liquid line, the control responds more slowly
and the result can be a fan that cycles on and off.
Therefore, whenever possible, it is preferable to mount the sensor in the upper 1/3
of the condenser instead of mounting it on the liquid line (see illustrations on Pages
11 and 12).
Appendix A
Temperature versus Probe Resistance
Appendix B
°C °F RESISTANCE (KΩ)
0° 32° 32.7
5° 41° 25.4
10° 50° 19.9
15° 59° 15.7
20° 68° 12.5
25° 77° 10.0
30° 86° 8.1
35° 95° 6.5
40° 104° 5.3
45° 113° 4.4
50° 122° 3.6

11
ICM326H Typical Installation
Consenser
Consenser
Consenser
Sensor
Sensor
Sensor
Fan
Motor 1
Motor 2
Line 1
Line 2 Line 2
Control
Circuitry
Reversing
Valve for
Heat Pump
This terminal to
be used for 240
VAC
ICM326H can monitor two additional condensers

12
ICM327H Typical Installation
Consenser
Consenser
Consenser
Sensor
Sensor
Sensor
Fan
Motor 1
Motor 2
Line 1
Line 2
Control
Circuitry
Reversing
Valve for
Heat Pump
ICM327H can monitor two additional condensers

6333 Daedalus Drive, Cicero, NY 13039
(Phone) 315-233-5266 (Toll Free) 800-365-5525 (Fax) 315-233-5276
www.icmcontrols.com
LIA148-1