Aprilaire 76 User manual

Model 76 Dehumidifier Control
Installation Instructions
READ AND SAVE THESE INSTRUCTIONS
CAUTION
1. Read all instructions before beginning installation.
2. Do not use in pool applications. Pool chemicals can damage the control.
3. Do not use solvents or cleaners on or near the display and circuit board.
Chemicals can damage components.
WARNING
1. Improper installation may cause property damage or injury. Installation, service,
and maintenance must be performed by a qualified service technician.
2. 120 Volts may cause serious injury from electric shock. Disconnect electrical
power before starting installation or servicing. Leave power disconnected until
installation/service is completed. This control is not a 120 Volt (line voltage)
device.
SAFETY INSTRUCTIONS
The Model 76 is for use with any dehumidifier as an EXTERNAL CONTROL,
including Aprilaire Models 1710A, 1730A, 1750A, 1770A, 1830, 1850 & 1870.
The Model 76 can also be used as a communicating REMOTE CONTROL
with Aprilaire Models 1710A, 1750A, 1770A, 1830, 1850 & 1870.
(See OVERVIEW on page 3 for details.)
1

TABLE OF CONTENTS
Safety Instructions.................. 1
Overview .......................... 3
Specifications...................... 3
Location Recommendations ......... 4
Installation
Mount Control . . . . . . . . . . . . . . . . . . . . . 5
Replacing a 1730A
Manual Dehumidistat ............. 6
Wiring to 1730A ................... 8
Wiring to 1710A/1750A/1770A
External Control .................. 9
Wiring to 1830/1850/1870
External Control ................. 10
Wiring to 1710A/1750A/1770A
Remote Control ................. 12
Wiring to 1830/1850/1870
Remote Control ................. 13
System Checkout
Power Up ........................ 15
Test Mode ....................... 17
Humidity/Dryness Level Setting...... 17
Offset ........................... 17
Turning On and Setting the Control ... 18
Sequence of Operation
External Control ................. 19
Remote Control ................. 19
Troubleshooting
Error Codes
External Control ................. 20
Remote Control ................. 20
Troubleshooting Guide.............. 23
OVERVIEW
The Aprilaire®Model 76 Dehumidifier Control provides control of the dehumidifier from the
living space.
The control can be installed as an EXTERNAL CONTROL, allowing the homeowner to set and
adjust the humidity setting and turn dehumidification on or off from a convenient location. In
this application, the Model 76 uses an onboard sensor to monitor the relative humidity (%RH)
in the space in which it is located and displays the measured relative humidity on the digital
display.
The control can also be installed to function as a REMOTE CONTROL if the dehumidifier
is located where it is not easy or convenient to access. This option is only available with
Aprilaire Dehumidifier Models 1710A, 1750A, 1770A, 1830, 1850 and 1870. The control can
be installed in any location within the living space, with the dehumidifier installed in the
area to be dehumidified, such as a crawl space, sealed attic, or basement. The dryness level
is set on the control and communicated to the dehumidifier. The dehumidifier communicates
the measured relative humidity in the space being dehumidified back to the Model 76 Control
where it is displayed on the digital display.
ELECTRICAL External Remote
Input Voltage and Current Voltage: 24VAC +/-20%
Current: 25mA (nominal),
50mA (max.) at 24VAC
Voltage: 9VDC (supplied by
dehumidifier control board)
Output Dry Contact, Normally Open Communication
SPECIFICATIONS
CONTROL External Remote
Control Range 40% – 80% RH 1 (less dry) – 7 (more dry)
65°F – 40°F Dew Point
Accuracy +/-5% RH
See Dehumidifier Specifications
Differential 3%
Low Limit 40°F Dew Point 50°F Dry Bulb
High Limit 99°F Dry Bulb 105°F Dry Bulb
32

LOCATION RECOMMENDATIONS
MOUNT CONTROL
•Inanareathehomeownerwantsto
monitor and control moisture levels.
•Onaninteriorwall.
•Approximately5’offthefloor.
•Atleast18”fromanoutsidewall.
DO NOT MOUNT CONTROL
• Intheflowofasupplyregister.
•Behinddoors,incornersorotherdeadairspaces.
•Indirectsunlight,nearlightingfixtures,orother
appliances that give off heat.
•Onanoutsideorunconditionedareawall.
•Instairwellsornearoutsidedoors.
•Onawallwithconcealedpipesorductwork.
FIGURE 1 – Mounting Control
90-1640
As a REMOTE CONTROL, the Model 76 can be mounted wherever is convenient for the
homeowner.
Follow the recommendations below when installing the Model 76 as an EXTERNAL CONTROL.
INSTALLATION
MOUNT CONTROL
If replacing a control mounted in the living space, see Control Mounted in Living Space on
page 6.
PULL APART
FRONT COVER
BACKING
PLATE
DH
DH
R/+
C/
-
B
A
FIGURE 2 – Disassemble Control
90-1631
BACKING PLATE
ANCHOR
SCREW
DH
DH
R/+
C/
-
B
A
FIGURE 3 – Mount Backing Plate
90-1632
54

REQUIRED COMPONENTS
18 – 24 gauge wire (field supplied) – 4 wires required, run new cable as needed.
(2)#8x1-1/2”mountingscrews(supplied)
(2) Anchors (supplied)
1. Level the backing plate on the wall and mark the mounting holes and wire access location
on the wall.
2.Drilltwo3/16”mountingholesanda3/4”wireaccesshole.SeeFigure 3.
3. Install the drywall anchors flush with the wall surface. Note: Mounting holes on the backing
plate are designed to fit on a horizontal J-box.
4. Run a 4-wire cable from the dehumidifier to the wall mount location and through the square
hole in the backing plate.
5.Securethebackingplatetothewallusingthetwo#8x1-1/2”screws.
REPLACING A 1730A MANUAL DEHUMIDISTAT
STEP 1 – REMOVE THE CURRENT MANUAL CONTROL
IF THE MANUAL CONTROL IS MOUNTED
IN THE LIVING SPACE:
1. Disconnect power to the dehumidifier
and HVAC system.
2. Pull knob from the dehumidistat cover and
remove cover from the control base.
3. Remove the four screws from the base
plate.
4. Pull the dehumidistat off the wall until wire
nuts are exposed.
5. Remove dehumidistat leads.
6. The existing 2-wire cable can remain. The Model 76 wiring requires 4 wires. Install more
wires as needed.
7. Mount the Model 76 control following steps 1-5 in the MOUNT CONTROL section above.
Reuse the existing wire access hole and wiring as needed.
8. Connect the existing wires (from 1730A REMOTE terminals) to the DH terminals and
connect the remaining two wires to the C/- and R/+ terminals on the Model 76 backing
plate.
9. Push excess cable into the wire access hole and fill the hole with insulation. Note: Failure
to seal the hole can cause drafts to enter the control and affect sensing accuracy.
10. Proceed to WIRING section on page 8.
FIGURE 4 – Manual Dehumidistat
IF THE MANUAL CONTROL IS MOUNTED ON A 1730A DEHUMIDIFIER:
NOTE: The Model 76 is installed in the living space and not on the dehumidifier.
See LOCATION RECOMMENDATIONS on page 4.
1. Disconnect power to the dehumidifier and HVAC system.
2. Pull knob from the dehumidistat cover and remove cover from the control base.
3. Remove the four screws from the base plate and pull the dehumidistat off the unit until
4” – 6”ofwireisoutsideoftheunit.
4. Cut the wires and use metal tape to secure the leads to the inside of the unit, preventing
contact with the blower.
5. Remove the gasket from the base plate.
6. Install the insulated cover plate (Service Part 4927) and gasket over the opening, using the
screws removed in step 3. See Figure 5.
7. Remove the wiring access panel on the outlet panel. See Figure 6.
8. Unplug the REMOTE terminals from the circuit board, remove the two wires and cut off the
bare leads. Once cut, the wires may remain in the unit.
9. Replace REMOTE terminals on circuit board and leave wiring access panel off for Model 76
wiring.
10. Proceed to WIRING section on page 8.
COVER PLATE
SERVICE PART 4927
FIGURE 5 – Inlet with Cover Plate
90-1642
WIRING ACCESS PANEL
FIGURE 6 – Wiring Access Panel
on Outlet
90-1633
76

WIRING
STEP 2 – SUPPLY 24VAC TO THE MODEL 76 CONTROL
The Model 76 control requires 24VAC when installed as an EXTERNAL CONTROL.
Pulling power from the HVAC system is the recommended method.
MODEL 76 TO 1730A
1. Disconnect power to the dehumidifier and HVAC system.
2. If replacing a dehumidistat that was in the living space, follow steps 3-6. If replacing a
dehumidistat that was on the dehumidifier, follow steps 7-13.
3. Connect the wires from the C/- and R/+ terminals on the Model 76 to the HVAC or
thermostat Cand Rterminals.
4. Connect the existing wires connected to the REMOTE terminals to the DH terminals on
the Model 76.
5. Snap the Model 76 front cover on the back plate. The 6-pin terminal aligns with the
terminal block receptacle on the back plate.
6. Proceed to SYSTEM CHECKOUT on page 15.
7. Remove the wiring access panel (if not already removed) on the dehumidifier outlet panel.
8. Unplug the REMOTE terminals from the circuit board.
9. Connect the wires from the DH terminals on the Model 76 to the REMOTE terminals and
plug the terminals back into the unit circuit board.
10. Connect the wires from the C/- and R/+ terminals on the Model 76 to the HVAC or
thermostat Cand Rterminals.
11. Replace the wiring access panel on the dehumidifier.
12. Snap the Model 76 front cover on the backing plate. The 6-pin terminal aligns with the
terminal block receptacle on the backing plate.
13. Proceed to SYSTEM CHECKOUT on page 15.
DH
DH
R/+
C/-
FLOAT
SWITCH
REMOTE
G-STAT
R-HVAC
G-HVAC
R
C
G
W
Y
HVAC
EQUIPMENT
R
C
G
W
Y
THERMOSTAT
EXISTING WIRING
ADDITIONAL MODEL 76 WIRING
B
A
FIGURE 7 – Model 76 to 1730A Wired to HVAC System
90-1641
MODEL 76 EXTERNAL CONTROL TO 1710A /1750A /1770A
1. Disconnect power to the dehumidifier and HVAC system.
2. Remove the control door on the dehumidifier inlet panel.
3. Connect one wire from the DH terminal on the Model 76 to the DH terminal on the control
board.
4. Connect the other wire from the DH terminal on the Model 76 to the Rf terminal on the
control board.
5. Connect the wires from the C/- and R/+ terminals on the Model 76 to the HVAC or
thermostat Cand Rterminals.
6. Set SYSTEM SETUP switch to EXTERNAL. See Figure 9.
7. Replace the control door on the dehumidifier.
8. Snap the Model 76 front cover on the backing plate. The 6-pin terminal aligns with the
terminal block receptacle on the backing plate.
MODEL
76
DAMPERS
Rf DH -WGhGs
Cf
VENT
HVAC EQUI
PR
EMOTE
DE
HB
+A
DEHUMIDIFIER
CONTROL BOARD
HVAC EQUIPMENTTHERMOSTAT
G
R
C
G
W
YY
W
C
R
SENSOR
ODT
FLOAT
SWITCH
EXISTING WIRING
ADDITIONAL MODEL 76 WIRING
R/+
B
C/
-
A
DH
DH
FIGURE 8 – Model 76 External Control to
1710A/1750A/1770A Wiring
90-1537
LOCAL
PRIMARY/SECONDARY
EXTERNAL
SYSTEM SETUP
HVAC FAN ON
VENT-TIMED
VENT-AUTO
PRIMARY
HVAC FAN OFF
ON
1234
FIGURE 9 – Model 76
External Control Dip
Switch Configuration
90-1538
Wiring Note: The dehumidifier Rf
and Cf terminals must be powered
from the transformer that powers
the Model 76 Control.
98

1. Disconnect power to the
dehumidifier and HVAC system.
2. Remove the wiring access
cover next to the control on the
dehumidifier. See Figure 10.
3. Wire the Model 76 to the
dehumidifier as shown in
Figure 11.
4. Ensure the NO/NC switch on the
dehumidifier control is set to NO
(see Figure 11).
+-AB ODT
SensorRemote
Gh Rf Cf Gs YW
HVAC EQUIP.
MODEL 76 CONTROL
FLOAT
Switch
DHDH
VENT DEH
Dampers
NC NO
NO/NC SWITCH
DH
DH
R/+
C/-
B
A
FIGURE 11 – Model 76 External Control to 1830/1850/1870 Wiring
90-1862
5. Snap the wiring access cover back into place, power up the dehumidifier and use the
ON/OFF button to turn the unit OFF (if ON).
90-1854
6. Press and hold the MODE button for 3 seconds to enter the Installer Set Up menu –
“REMOTEDISABLED”willappearonthedisplaywhenInstallerSetUpisentered.
7.RepeatedlypresstheMODEbuttonuntil“EXTERNALDISABLED”showsonthedisplay.
8.PresstheUPorDOWNbuttontochangeto“EXTERNALENABLED”.
90-1854
9.RepeatedlypresstheMODEbuttonuntil“DONE”appearsonthedisplay.
MODEL 76 EXTERNAL CONTROL TO 1830/1850/1870
CONTROL
PANEL COVER
CONTROL WIRING
ACCESS
COVER
FILTER ACCESS DOOR
FIGURE 10 – Wiring Access Cover Location
90-1884
1110

MODEL 76 REMOTE CONTROL TO 1710A /1750A /1770A
1. Disconnect power to the dehumidifier and HVAC system.
2. Remove the control door on the dehumidifier inlet panel.
3. Connect one wire from the Aterminal on the Model 76 to the Aterminal on the control
board.
4. Connect one wire from the Bterminal on the Model 76 to the Bterminal on the control
board.
5. Connect one wire from the R/+ terminal on the Model 76 to the +terminal on the control
board.
6. Connect one wire from the C/- terminal on the Model 76 to the –terminal on the control
board.
7. Set SYSTEM SETUP switches to LOCAL and PRIMARY, See Figure 13.
8. Replace the control door on the dehumidifier.
9. Snap the Model 76 front cover on the backing plate. The 6-pin terminal aligns with the
terminal block receptacle on the backing plate.
MODEL
76
DAMPERS
Rf DH -WGhGs
Cf
VENT
HVAC EQUIP REMOTE
DE
HB
+A
DEHUMIDIFIER
CONTROL BOARD
SENSOR
ODT
FLOAT
SWITCH
R/+
B
C/
-
A
DH
DH
FIGURE 12 – Model 76 Remote Control to
1710A/1750A/1770A Wiring
90-1537
LOCAL
PRIMARY/SECONDARY
EXTERNAL
SYSTEM SETUP
HVAC FAN ON
VENT-TIMED
VENT-AUTO
PRIMARY
HVAC FAN OFF
ON
1234
FIGURE 13 – Model 76
Remote Control Dip
Switch Configuration
90-1538
MODEL 76 REMOTE CONTROL TO 1830/1850/1870
1. Disconnect power to the
dehumidifier and HVAC system.
2. Remove the wiring access
cover next to the control on the
dehumidifier. See Figure 14.
3. Wire the Model 76 to the
dehumidifier as shown in
Figure 15.
CONTROL
PANEL COVER
CONTROL WIRING
ACCESS
COVER
FILTER ACCESS DOOR
FIGURE 14 – Wiring Access Cover Location
90-1884
+-AB ODT
SensorRemote
Gh Rf Cf Gs YW
HVAC EQUIP.
DH
DH
R/+
C/-
B
A
MODEL 76 CONTROL
FIGURE 15 – Model 76 Remote Control to 1830/1850/1870 Wiring
90-1860
1312

SYSTEM CHECKOUT
POWER UP
1. Check all wiring.
2. Plug in dehumidifier and restore power to the HVAC system.
3. Turn on/off switch on dehumidifier ON. After a 4 second start up sequence all buttons on the
Model 76 will be functional.
 •ThecontrolwillbeOFF.
 •Thehumiditysettingwillbe60%ifwiredforEXTERNALCONTROL.Thedrynesslevelwill
be set to 3 if REMOTE CONTROL.
 •Thecontrolwilldisplaythemeasuredhumidity.
– EXTERNAL CONTROL displays humidity measured by the controlinit’sinstalledspace.
– REMOTE CONTROL displays humidity measured by the dehumidifierinit’sinstalledspace.
FIGURE 16 –
External Control
90-1636
Model 76 Control
Model 76 LCD Display
Blinking ON +*: Control Limit Exceeded.
See Control Limits, page 19.
Solid ON:
Control On
Blinking ON:
Dehumidifying
Measured
Humidity or
Setting
Control On/Off
Humidity Setting
and Offset
Adjustment
Control must be
ON to adjust offset
and setting.
SET: Shows when
humidity setting
displayed or being
changed.
OFF: Control Off
4. Snap the wiring access cover back into place, power up the dehumidifier and use the
ON/OFF button to turn the unit OFF (if ON).
90-1854
5. Press and hold the MODE button for 3 seconds to enter the Installer Set Up menu –
“REMOTEDISABLED”willappearonthedisplaywhenInstallerSetUpisentered.
6.PresstheUPorDOWNbuttontochangeto“REMOTEENABLED”.
90-1854
7.PresstheMODEbuttonand“DONE”willappearonthedisplay.
1514

FIGURE 17 –
Remote Control
90-1636
Model 76 Control
Model 76 LCD Display
Solid ON:
Control On
Blinking ON:
Dehumidifying
Measured Humidity
in Remote Location
or
Dryness Level Setting Control On/Off
Dryness Level
Control must be
ON to adjust.
SET: Shows when
dryness level
setting displayed
or being changed.
Does not display
when setting
dryness level
OFF: Control Off
TEST MODE
1. Press and hold the ON button for 5 seconds to enter Test Mode.
a. Verify the measured humidity is displayed on the Model 76 screen.
b. Verify dehumidifier turns on, and ON blinks on the Model 76 screen.
c. Verify the *is displayed on the Model 76 screen when wired as a REMOTE CONTROL.
2. After 5 minutes or after pressing the OFF button, the control will enter Off mode.
a. Verify the dehumidifier turns off.
HUMIDITY/ DRYNESS LEVEL SETTING
•ThecontrolmustbeONtoadjustthehumidityordrynesslevelsetting.
•The (up) and (down) buttons are used to increase or decrease the setting.
•ThefirstpressofeitherbuttonwilldisplaythecurrentsettingandSET on the LCD display.
•Eachsubsequentpushoftheupordownbuttonswillchangethesettingby1%or1dryness
level.
•Ifabuttonishelddown,thesettingwillcontinuallychangeby1%or1drynesslevelevery
1/2 second for as long as the button is pressed.
•ThecontrolwillreturntoNormalMode,displayingthemeasuredhumidity,5secondsafter
the last button press/release.
OFFSET
When the Model 76 is installed as an EXTERNAL
CONTROL, an offset can be applied to the humidity
reading to avoid discrepancies with other humidity
measuring devices in the home. Allow 48 hours for
the control to acclimate before applying an offset. The
control must be ON to enter the Offset screen.
NOTE: This feature is not available when the control
is installed as a REMOTE CONTROL.
•PressandholdtheOFFbuttonfor5secondsto
enter the Offset screen.
•The buttons can be used to set an offset
value between -5% RH and +5% RH.
•ThecontrolwillreturntoNormalMode,displaying
the measured humidity, 5 seconds after the last
button press/release.
FIGURE 18 – Offset Screen
90-1638
1716

SEQUENCE OF OPERATION
EXTERNAL CONTROL
Normal Mode
•Whenthemeasuredhumidityisgreaterthanthesetting,thecontrolwillactivatethe
dehumidifier output, the dehumidifier will begin dehumidifying and ON will blink on the
LCD display.
•Whenthemeasuredhumidityfalls3%belowthesetting,thecontrolwilldeactivatethe
dehumidifier output, the dehumidifier will stop dehumidifying and the LCD will display a
solid ON.
Control Limits
•Ifthecontrolmeasuresadewpointbelow40°FORatemperatureabove99°F,thecontrol
will deactivate the dehumidifier output if actively dehumidifying, the dehumidifier will stop
dehumidifying, and ON and *will blink on the LCD screen.
•Thecontrolwillresumenormaloperationwhenthemeasureddewpointisgreaterthan45°F
or the measured temperature is below 94°F, whichever control limit was exceeded.
REMOTE CONTROL
Normal Mode
•OnceduringeveryCyclePeriod(setbythedipswitchesinthedehumidifier)thedehumidifier
blower and dehumidifier damper output will turn on and sample the air in the area served by
the dehumidifier. Sampling will also occur whenever the dryness level setting is increased on
the Model 76 Control.
•Afterthreeminutes,thedewpointoftheincomingairismeasuredandcomparedtothe
dryness level set on the Model 76 Control. If the dew point of the incoming air is above the
setting, the compressor turns on and ON will flash on the Model 76 screen.
•Thedewpointoftheincomingairiscontinuouslymonitoredduringcompressoroperation.
When the dew point of the incoming air falls below the dryness level setting, the dehumidifier
compressor and blower will turn off and ON will stop flashing on the Model 76 screen.
Control Limits
The control limits are determined by the dehumidifier.
•Ifthedehumidifiersensesincomingairbelow50°Forabove105°F,thedehumidifierwillstop
compressor operation if actively dehumidifying and ON will stop flashing on the Model 76
screen.
•Thedehumidifierwillresumenormaloperationwhenthemeasuredincomingairtothe
dehumidifier is between 55°F and 100°F.
TURNING ON AND SETTING THE CONTROL
EXTERNAL CONTROL
1. Press the ON button.
2. Use the buttons to set the control at 59%.
Increasing the humidity setting will decrease dehumidifier run time, allowing for higher
humidity levels.
Decreasing the humidity setting will increase dehumidifier run time, allowing for lower
humidity levels.
REMOTE CONTROL
1. Press the ON button.
2. Use the buttons to set the
control to a 3 dryness level.
Increasing the dryness level will
increase dehumidifier run time,
allowing for lower humidity levels.
Decreasing the dryness level will
decrease dehumidifier run time,
allowing for higher humidity levels.
The dryness level settings can be
approximated to relative humidity (%RH)
using Table 1.
TABLE 1 – %RH (+/-5%) Based on Dryness
Level Setting & Indoor Temperature
Dryness
Level
Setting
Indoor Temperature (°F)
65 70 75 80
184% 71% 60%
286% 73% 61% 52%
374% 63% 53% 45%
464% 54% 45% 39%
555% 46% 39% 33%
647% 39% 33% 28%
740% 34% 28% 24%
Note: This table is for reference only.
1918

Technical Support is available Monday through Friday, 7:00 a.m. to 5:00 p.m. CST, at
[phone]. Use the guide on the following page to help find and correct system faults.
Contact Technical Support before replacing the control or for additional troubleshooting.
TROUBLESHOOTING
EXTERNAL CONTROL
When the control detects an internal error, it
will stop controlling, deactivate the dehumidifier
output, and the LCD will display the Error Code.
See Figure 19. The control will attempt to recover
from the error every 10 minutes. The Error Code
will continue to be displayed as long as the error
condition exists. Button presses are not registered
when in Error Mode. Cycling power to the control
will not clear the code and the control will need to
be replaced.
REMOTE CONTROL
When there is a dehumidifier or control communication fault, all dehumidifier outputs will turn
off and the Model 76 LCD will display an Error Code. See Figure 20 for an example. The faults
can either be critical or non-critical. Any fault will
result in all dehumidification outputs turning off.
A critical fault is cleared by repairing the fault
and cycling power using the on/off switch on
the dehumidifier. A non-critical fault is cleared
by repairing the fault and cycling power to the
dehumidifier is not required. See Table 2 for the
error codes and required action.
ERROR CODES
FIGURE 19 – External Control
Error Code Screen
FIGURE 20 – Remote Control
Error Code Screen
90-1645
90-1645
TABLE 2 – Error Codes
Error Code Failure Mode Action Reset
E1 Internal Humidity
or Temperature
Sensor Open or
Shorted
1. Check the connection between the sensor board
and control board.
2. If connection okay, replace sensor board, Part No.
5460.
Cycle Power
E2 High Refrigeration
Pressure
1. Verify that the fan works, the backflow damper
swings freely and there is no blocked or
restricted ductwork.
2. If the fault persists, call Technical Support.
Cycle Power
E3 Model 76
Remote Control
Communication
Loss
1. Check connections between Model 76 and
dehumidifier control board. Terminals should be
fully inserted and secured in the control board
and Model 76 control terminals.
2. If connections are correct and secure, turn off
the dehumidifier and remove the Model 76. Use
a short section of 4-wire cable to reconnect
the Model 76 to the control board. Turn the
dehumidifier back on and increase the dryness
level setting on the Model 76. If the dehumidifier
turns on, the problem is with the wiring between
the dehumidifier and control.
3. If the dehumidifier does not turn on, call
Technical Support.
Self-Correcting
E4 Insufficient
Capacity
1. Check the frost sensor connection at the power
board. Terminal should be fully seated on the
power board pins.
2. Remove the side access panel and verify that the
sensor is secured to the suction line.
3. If the sensor is connected and secured to the
refrigeration line proceed to the next step.
4. Reset the fault by cycling power to the
dehumidifier.
5. Turn the humidity setting down (below room/
home humidity level) to make a dehumidification
call.
6. Allow the fan and compressor to run for
approximately 10-15 minutes and then enter
diagnostic test mode by simultaneously pressing
the UP ARROW and MODE buttons for 3 seconds.
The LCD will display the temperature measured
by the internal sensor while also displaying AIR
SAMPLING and ON, the humidity measured by
the internal sensor while also displaying %RH
and ON, and the frost sensor temperature while
also displaying ON. Scroll through these values
and by using the UP/DOWN arrow buttons.
7. Record values and call Technical Support.
Cycle Power
2120

TABLE 3 – Troubleshooting Guide
Symptom Possible Reason Troubleshooting Procedure
No power to the
control.
Incorrect wiring. Verify wiring connections between control,
dehumidifier and HVAC system (where applicable).
No power to dehumidifier. •VerifythatthedehumidifierpowerswitchisON.
•Verifythecircuitbreakerhasnottripped.
No power to HVAC
equipment.
•VerifyHVACsystemswitchison.
•Verifythecircuitbreakerhasnottripped.
Control does
not turn on
dehumidifier
output.
Incorrect wiring. Verify wiring connections between control and
dehumidifier.
Blank display or
missing segments
during Test mode.
LCD error. Replace control.
Display shows Er. Control detected an
internal error.
The control will need to be replaced.
Display shows
E1-E9.
Dehumidifier or
communication error.
Use Table 2 to troubleshoot fault.
Inaccurate
humidity reading
when using
External Control.
Control recently installed
after being stored in an
uncontrolled temperature and
humidity environment.
Allow 48 hours for control to acclimate.
Offset has been applied to
the humidity reading.
Change the offset.
Control is mounted in direct
sunlight, above a heat or
humidity source, or in the
path of a supply register.
Relocate the control.
TABLE 2 – Error Codes (continued)
Error Code Failure Mode Action Reset
E5 High Temperature
Thermistor Failure
1. Check the high temperature sensor connection at
the power board. Terminal should be fully seated
on the power board pins.
2. Remove the side access panel and verify the
sensor is not damaged and connected to the
refrigeration line coming from the compressor.
3. If the sensor is connected and secured to the
refrigeration line, contact Technical Support.
Cycle Power
E6 Low Temperature
Thermistor Failure
1. Check the low temperature sensor connection at
the power board.
2. Remove the side access panel and verify the
sensor is not damaged and connected to the
suction line.
3. If the sensor is connected and secured to the
refrigeration line, contact Technical Support.
Cycle Power
E7 Float Switch
Open
1. Empty the condensate pan.
2. Check the float switch connection at the control
board.
3. If not using a float switch, verify jumper is
between float switch terminals on dehumidifier
control board.
4. If the problem persists, replace the float switch.
Self-Correcting
E8 Inlet Air
Temperature Out
of 50°F – 104°F
or dew point
below 40°F
1. Verify all ductwork is properly sealed.
2. If no signs of leak points, contact Technical
Support.
Self-Correcting
E9 Outdoor
Temperature
Sensor Open or
Shorted
1. Check the sensor connection at the power board.
2. Remove the wires from the terminals and
measure the resistance. An short circuit will
have a resistance very close to 0 Ohms and an
open circuit will have a very very high resistance.
The table below can be used to approximate the
resistance based on outdoor temperature.
Outdoor Temperature Resistance
0°F 84,500 Ohms
20°F 46,000 Ohms
40°F 26,000 Ohms
60°F 15,500 Ohms
80°F 9,500 Ohms
100°F 6,000 Ohms
3. If the sensor is not reading correctly, replace the
sensor, Part No. 8052.
Self-Correcting
2322

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www.aprilairepartners.com
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