Aprilaire 1710A Programming manual

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Aprilaire Dehumidifier Troubleshooting Manual
Models 1710A, 1750A, 1770A
Table of Contents
Troubleshooting Fault Codes ....................................................................................................................... 1
1 blink ............................................................................................................................................... 2
2 blinks ............................................................................................................................................. 2
3 blinks ............................................................................................................................................. 2
4 blinks ............................................................................................................................................. 2
5 blinks ............................................................................................................................................. 6
6 blinks ............................................................................................................................................. 6
7 blinks ............................................................................................................................................. 6
Verifying Capacity......................................................................................................................................... 8
Water Leaks ................................................................................................................................................ 11
Fan Does Not Function ............................................................................................................................... 1
Circuit Breaker Trips ................................................................................................................................... 13
1710A/1750A/1770A Parts List .................................................................................................................. 14
1710A/1750A Electrical Schematic ............................................................................................................ 16
1770A Electrical Schematic ........................................................................................................................ 17
Instruments you will need to complete troubleshooting:
1. Digital Multi-Meter (DMM) capability of measuring
•AC and DC voltage
•Resistance
•Capacitance
2. emperature Meter for air temperature
3. Humidity Meter for air RH
Minimum tools needed to complete troubleshooting:
1. Phillips screwdriver (#2) or drill driver with #2 Phillips bit
2. Small (terminal) flat head screwdriver
3. Needle nose pliers
4. Level (to troubleshoot water leak claims)
Note: Do not hook up refrigeration gauges to the dehumidifier. Use of gauges will result in
refrigerant loss and performance loss.

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Troubleshooting Fault Codes
The red Fault LED on the control board ill blink to indicate a fault. The number of blinks determines
the fault that as detected – carefully count the number of blinks:
1 blink The control board is not receiving a good signal from the thermistor on the sensor arm.
1. Turn off po er to the dehumidifier using the ON/OFF s itch and remove the sensor arm
(can be accessed through the filter door). Inspect the pins on the sensor arm, if they are
bent they ill likely fail so replace the sensor arm.
2. Inspect the socket the sensor arm plugs into on the control board – if it iggles ith very
little effort, then one or more pins have likely broken from the control board and you ill
need to replace the control board.
blinks The control board is not receiving a good signal from the RH sensor on the sensor arm.
1. Turn off po er to the dehumidifier using the ON/OFF s itch and remove the sensor arm
(can be accessed through the filter door). Inspect the pins on the sensor arm, if they are
bent they ill likely fail so replace the sensor arm.
2. Inspect the socket the sensor arm plugs into on the control board – if it iggles ith very
little effort, then one or more pins have likely broken from the control board and you ill
need to replace the control board.
3 blinks A Model 70 or Model 76 control, ired to the Remote terminals of the control board, had
communication, but has no stopped communicating.
1. Use the color of the ire connected to the A, B, + and – (on the Model 76, the “+” and “-“
terminals are labeled “R/+” and “C/-“) terminals on both the base of the Model 70 or 76
and the dehumidifier control board to verify that they are ired correctly. Make sure the
terminal scre s on both the control board and the Model 70 or 76 base are tight.
Note: The Model 76 has t o “DH” terminals – these should not be used hen it is ired
to the Remote terminals on the control board.
2. If connections are correct and secure, turn off the dehumidifier and remove the Model
70 or 76 control. Use a short section of 4- ire cable to reconnect the control to the
control board to see if there is a problem ith the existing ire. Turn the dehumidifier
back on. If the “3 blinks” fault continues, the Model 70 or 76 must be replaced, if the
fault is gone, then the ire bet een the control and the dehumidifier must be replaced.
4 blinks The temperature of the suction line, as sensed by the Frost Sensor, has not dropped at least
5°F lo er than the incoming air temperature in 20 minutes. The t o reasons that this ould
happen is that the compressor is not running, or the refrigeration system is not operating
properly.

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1. Turn the ON/OFF s itch OFF, and turn the control knob to OFF to reset the fault.
2. Turn the ON/OFF s itch back ON and after 10 seconds, turn the control knob to Test.
The dehumidifier blo er ill turn on for 3 minutes ith the green Status LED blinking,
and then the compressor ill turn on ith the green Status LED staying on continuously.
You should be able to hear the compressor kick in.
If the compressor doesn’t start (go to step 3), there is an electrical issue to address. If
the compressor does start (go to step 4), then you ill need to verify that the
refrigeration system is orking properly.
3. If the compressor doesn’t start
a. Turn the control knob to OFF and the ON/OFF s itch to OFF.
b. Remove the front panel of the dehumidifier.
c. Verify that the bro n and orange ires are connected to the po er board. Verify
that t o bro n ires are connected to one pole of the run capacitor and one red
ire is connected to the other pole. Give each ire a light tug to make sure all
connections are sound.
•If any of the wires were disconnected, place the front panel back on (do not
secure ith scre s yet), turn the ON/OFF s itch ON and turn the control knob
to Test to verify the compressor starts. If it starts, go to step 4 to verify the
performance of the refrigeration system before leaving. If it still does not start,
continue to the next step (d.).
•If none were disconnected, continue to the next step (d.).
d. Turn the ON/OFF s itch back ON. With the front panel still off, stay clear of the
blo er motor and turn the control knob to Test. When the green Status LED on the
control board turns on continuously, you should a hear the “click” of the
compressor relay and see that the red LED on the po er board that is labeled
“COMP” is on. There should be t o red LED’s lit on the po er board: the FAN LED
and the COMP LED.
If the COMP LED is not on, turn the ON/OFF s itch OFF and disconnect the t o
black high temperature s itch ires from the po er board. Verify continuity
(resistance near zero) across the t o high temperature s itch ires. If there is no
continuity, the high temperature s itch ill need to be replaced. If there is
continuity, reconnect the s itch ires and turn the ON/OFF s itch back ON.
For older power boards, the high temperature switch and ribbon cable are connected
to a daughter board that attaches to the power board. Disconnect the high
temperature switch wires and verify that the daughter board is securely attached to
the power board and that the socket on the daughter board is not loose. If the
socket is loose replace the daughter board.

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DO NOT MEASURE RESISTANCE OR DO A CONTINUITY CHECK OF THE HIGH
TEMPERATURE SWITCH WHILE THE SWITCH IS CONNECTED TO THE POWER BOARD
– DAMAGE TO THE CONTROL CAN OCCUR.
If the high temperature switch is good, disconnect the ribbon cable (the
ON/OFF s itch should be ON) from the control board and use a small piece of
solid (not stranded) ire, a paper clip or the leads of an ammeter to touch
together pads 4 and 7 on the ribbon cable.
•If the compressor turns on the control board ill need to be replaced.
•If the compressor does not turn on, the po er board ill need to be
replaced.
e. If the COMP LED is on but the compressor is not, measure the voltage at the COMP
BRWN and NTRL ORG terminals on the po er board.
•If the voltage is 1 0VAC (nominal) then the problem lies ith the run capacitor,
the connections at the compressor or the current limiting s itch under the
compressor cap.
oDisconnect the ires connected run capacitor and the orange ire
connected to the po er board. Measure the capacitance of the run
capacitor – it should be 55 microfarads ± 5% for the 1710A/1750A and 60
microfarads ± 5% for the 1770A. If not, replace the capacitor.
oMeasure the resistance across the compressor harness ires. Actual
measurements may be a little different, but should be approximately:
Orange – Red: 1.1Ω, Orange – Bro n: 1.9Ω, Red – Bro n: 2.7Ω. If the
Orange-Red and Orange-Bro n measurements are open (infinite) but the
Red-Bro n measurement is normal, than the compressor overload s itch
under the compressor cap needs to be replaced. If just one is open, then it
is likely a connection at the compressor has come loose – remove the
compressor cap and check the terminal connections.
•If the voltage is 0 VAC, inspect the large disk-like component (this is a varistor
and it is usually blue or black in color) on the po er board right next to the
compressor terminals. If this component looks scorched or cracked, replace the
po er board. If the varistor does not look damaged then the problem is ith
the control board and it must be replaced.
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4. If the compressor does start, verify that the refrigeration system is operating sufficiently
to prevent a “4-blinks” fault.
a. If applicable, disconnect the duct from the discharge of the dehumidifier. Verify that
the flap damper on the outlet of the dehumidifier opens/closes freely.
b. Verify that there is not a lengthy amount of duct ork (more than 50 feet) attached
to the inlet side, that the duct ork is free of obstructions and kinks and that the filter
is clean – remove the filter for this test if dirty.
c. Ensure the front and back panels are in place and
assembled ith scre s. DO NOT REMOVE PANELS
DURING THIS TEST.
d. Remove the control door. Disconnect all electrical
connections to the HVAC equipment by removing the
HVAC Equipment terminal block from the control
board. Disconnect any remote control by removing
the REMOTE terminal block.
e. Move the LOCAL/EXTERNAL System Setup dip s itch
on the control board to LOCAL (if the s itch is labeled
A/B, no need to change the position)
f. Adjust the control knob to the highest setting – 7 (do
not put the unit in TEST mode as this ill allo the
compressor run for only one minute) to initiate a
dehumidifier call.
g. Before the compressor starts, measure the DC voltage
across the frost sensor terminals on the control
board. Do not disconnect the wires from the terminals when reading the voltage.
The voltage represents a temperature and should be near the temperature of the
incoming air. The voltage should start to increase as the coil gets colder.
h. Measure the voltage again after 10 minutes of compressor run time to determine if it
has increased. The voltage should increase to indicate a temperature drop of ten
Frost Sensor
Voltage (DC)
Frost Sensor
Temperature (°F)
Frost Sensor
Voltage (DC)
Frost Sensor
Temperature (°F)
1.903
35
1.495
65
1.842
40
1.414
70
1.778
45
1.329
75
1.713
50
1.235
80
1.644
55
1.132
85
1.572
60
1.016
90
Frost Sensor
Terminals
Top Dip Switch is
Local/External
HVAC Equipment
Terminal Block
Remote Term
inal
Block

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degrees (10°) or more. If the inlet air temperature is cold (i.e. around 60°F or lo er)
the drop may be slightly less than 10°F, but should be more than 5°.
•If there is no temperature drop (no voltage increase) then there is likely a
refrigerant leak and the unit ill need to be replaced.
•If there is a temperature drop, but not as much as expected, allo the
compressor to continue to run an additional 10 minutes and check again.
•If the temperature drop is 10° or more, then continue on to “Verifying Capacity”
on page 8 to determine the actual performance.
5 blinks The temperature of the incoming air is less than 50°F or is higher than 100°F hen the
compressor is attempting to start. The most likely cause for this failure mode is that the
dehumidifier is installed in an application ith temperatures outside of the specification for
this product or there are leaks in the duct ork causing temperature extremes at the
dehumidifier inlet.
1. Turn the ON/OFF s itch OFF and to reset the failure.
2. Consider the follo ing for the application:
•All installations – If ducting to the HVAC system, make sure the inlet to the dehumidifier
is not ducted to the supply side of the HVAC system.
•Attic installations – Inspect the duct ork attached to the inlet of the dehumidifier for
leaks if the ambient temperature is high.
•Basement installations – Lo temperature may be offset by mixing air from the home
into the dehumidifier.
•Cra lspace space applications – The dehumidifier ill correct itself hen the lo
temperature conditions stop.
•Ventilation applications – High or lo temperatures may be offset by mixing air from the
home into the dehumidifier.
6 blinks The signal from the Frost Sensor is out of the allo able range (-20°F to 150°F). The most
likely reason for this fault is a poor connection at the control board or a damaged sensor.
1. Check the Frost Sensor connections at the control board. Tug on the ires to verify that
the quick connect terminals connection to the ires are not loose.
2. Remove the front panel and inspect the sensor. If it looks crushed or damaged, replace
the sensor.
3. With the ON/OFF s itch ON and the control knob set to OFF, measure the voltage at the
frost sensor terminals. Do not disconnect the ires from the terminals hen reading the
voltage (see page 5). The voltage should correspond approximately to room temperature
in accordance ith the tables on page 5.
7 blinks The Float S itch input to the control board is open. This ill occur if there is a float s itch
installed, and there is sufficient ater in the secondary drain pan to cause the float s itch to

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open, or if the installed float s itch is faulty or not the appropriate type (must be a normally
open s itch that is not po ered). If a float s itch is not installed, the jumper in the Float
S itch terminals is missing or not properly seated.
1. Leave the unit ON ith the fault code blinking. It ill stop blinking ithout having to turn
the unit OFF to reset hen the fault has been repaired.
2. Drain the ater out of the drain pan.
3. Remove the Float S itch terminal block from the control board and inspect the terminal
block to ensure the ires are properly seated. If a float s itch is installed, do a
continuity check bet een the float s itch terminals – there should be continuity.
Replace the float s itch if needed.
4. If a jumper is installed, remove the jumper and reinstall paying particular attention to the
retention of the ire ithin the terminal.

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Verifying Capacity
If the unit is functioning properly, and there are no fault codes present, this procedure can be used if
there is concern that the dehumidifier is not removing sufficient moisture. After the dehumidifier
reaches stable operating conditions, measure the inlet air temperature and RH and compare it to the
outlet air temperature and RH. Use the graphs provided to convert the inlet and outlet air conditions to
air moisture content to calculate if the moisture being removed is near the performance levels sho n in
the table on page 11. If the inlet air conditions are not ithin those listed on the table, contact Aprilaire
Technical Support Monday through Friday from 7:00 a.m. to 5:00 p.m. CST at [phone] for
assistance in determining performance. The dehumidifier ill not remove moisture if the de point of
the inlet air is 40°F or lo er.
1. Verify that the flap damper on the outlet of the dehumidifier opens/closes freely.
2. Verify that the duct ork is free of obstructions and kinks and that the filter is clean – remove
the filter for this test if dirty.
3. Ensure the front and back panels are in place and assembled ith scre s. DO NOT REMOVE
PANELS DURING THIS TEST.
4. Remove the control door. Disconnect all electrical connections to the HVAC equipment by
removing the HVAC Equipment terminal block from the control board. Disconnect any remote
control by removing the REMOTE terminal block.
5. Move the LOCAL/EXTERNAL dip s itch on the control board to LOCAL
6. Replace the control door.
7. Adjust the control knob to the highest setting – 7 (do not put the unit in TEST mode as this ill
allo the compressor to run for only one minute) to initiate a dehumidifier call. Note: If the
de point of the air is belo 40°F, the dehumidifier compressor ill not turn on.
8. Remove one of the filter doors and insert a temperature/humidity measuring instrument in
front of the filter/coil. Close the filter door as much as possible during the reading.
9. Allo time for the measuring instrument to get a good, stable reading.
10. Record the dry-bulb temperature and RH of the inlet air.
11. Find the inlet air moisture content in the graph appropriate for the model being tested belo .
Locate the inlet air temperature at the bottom of the graph and dra a straight line up until you
meet the inlet air RH curve then read the moisture content at the left (360 PPD @ 80°, 60% RH
for Model 1710A/1750A example sho n).

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1
2

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12. Move the temperature/humidity measuring instrument to the discharge of the dehumidifier.
13. Allo time for the measuring instrument to get a good, stable reading.
14. Record the dry-bulb temperature and RH of the discharge air.
15. Find the discharge air moisture content in the graph appropriate for the model being tested
belo . Use the 1750A graph for the model 1710A. Locate the discharge air temperature at the
bottom of the curve and dra a straight line up until you meet the discharge air RH curve then
read the moisture content here the t o intersect at the left (265 PPD @ 100°, 24% RH
example sho n).
1
2

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16. Subtract the discharge air moisture content from the inlet air moisture content to determine the
amount of moisture being removed by the dehumidifier.
Inlet Air Moisture ______ ppd @ ___ °F, ___ % RH
Discharge Air Moisture ______ ppd
Dehumidifier Capacity______ ppd
17. Compare the capacity to the approximate performance in the table belo . Performance should
be ithin about 20% of the capacity listed belo :
Inlet Air RH
Inlet Air Temperature (°F)
60
65
70
80
50%
N/A
45 ppd
57 ppd
75
ppd
60%
43 ppd
66 ppd
78 ppd
90 ppd
ater Leaks
Water collects in the drain pan belo the coils and is directed through the drain tube to the outlet at the
outlet side of the dehumidifier. A custom running trap is provided ith the dehumidifier that is deeper
than a standard running trap – do not use any other trap than hat is provided ith the unit. The
models 1710A, 1750A and 1770A are negative pressure cabinets and the trap prevents air from being
pulled in through drain tube and subsequently pushing ater back up into the drain pan.

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1. Level the unit front to back, and side to side. The unit may be installed ith a slight slope
to ard the drain outlet, but must be level side to side.
2. Turn the ON/OFF s itch OFF then remove the front panel from the dehumidifier and examine
the insulation on the base to look for any signs of ater inside the cabinet. Wipe up any ater
that has collected in the base.
3. Clean the drain trap and clean or replace the drain tubing. The drain tubing must have a
continual do n ard slope to the drain.
IMPORTANT: If using ½” vinyl tubing for the drain line, ensure that there are no up ard bends
in the tube that could act as a secondary trap – this ill cause an air-lock that could prevent the
flo of ater to the drain.
4. With the front panel still off, slo ly pour a pint of ater into the drain pan near the return
bends of the coils. After the running trap fills, the ater should flo out the drain tube to the
drain.
5. Plug or raise the drain tube sufficiently high to prevent ater from pouring out of the drain
tube. Slo ly pour in an additional pint of ater until the bottom of the drain pan is filled. Allo
15-20 minutes for the ater to stand in the drain pan and look for any signs of leaks from the
drain pan and drain tube. Unplug the drain and allo the ater to drain out.
6. Replace the front panel. Remove one filter door and slide out the filter about 6”.
7. S itch the ON/OFF s itch ON and turn the control knob to Test.
8. After the blo er starts, slo ly pour another pint of ater into the drain pan just belo the
bottom of the evaporator coil in the area here the filter has been pulled from. This ill sho
that the unit is draining ith the highest negative pressure in the cabinet.
Blower Does Not Function
1. Make sure the outlet into hich the dehumidifier is plugged has 120 VAC available.
2. Turn the ON/OFF s itch OFF and the control knob to OFF.
3. Remove the front panel and disconnect the blue and yello fan ires from the po er board.
4. Inspect the large disk-like component (this is a varistor and it is usually blue or black in color) on
the po er board right next to the fan terminals. If this component looks scorched or cracked,
replace the po er board.
5. Turn the ON/OFF s itch to ON and the control knob to TEST and after the green Status LED on
the control board starts to flash, measure the AC voltage at the fan terminals on the po er
board. Use caution as this is line voltage.
•If the FAN LED on the power board is lit and there is 1 0 VAC at the fan terminals,
replace the blo er/motor assembly.
•If the FAN LED on the power board is lit and there is 0 VAC, turn the ON/OFF s itch
OFF and reconnect the fan ires to the po er board. Turn the ON/OFF s itch back ON
and disconnect the ribbon cable from the control board.

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Use a small piece of solid (not stranded) ire, a paper clip or the leads of an ammeter to
touch together pads 4 and 6 on the ribbon cable.
•If the fan turns on the control board ill need to be replaced.
•If the fan does not turn on, the po er board ill need to be replaced.
Circuit Breaker Trips
The 1710A and 1750A must be plugged into an outlet served by a 15 amp circuit breaker; the
dehumidifier uses approximately 8 amps at high load (i.e. hot and humid) conditions and less at lo load
conditions.
The 1770A must be plugged into a 20 amp outlet and be served by a 20 amp circuit breaker; the
dehumidifier uses approximately 14 amps at high load (i.e. hot and humid) conditions and less at lo
load conditions.
If there are other electrical components that dra a lot of current connected to the same circuit
breaker, the circuit may be overloaded and a ne circuit should be run to serve the dehumidifier.
Consult ith a qualified electrical contractor if there are questions as to the suitability of the circuit into
hich the dehumidifier is plugged.
If the electrical service is sound, there are t o primary reasons hy a circuit breaker ould trip: a ire
has disconnected or the compressor run capacitor is faulty.
1. Turn the ON/OFF s itch OFF and remove the front panel from the dehumidifier.
2. Inspect the electrical connections at the po er s itch, po er board, contactor (Model 1770A
only) and run capacitor.
3. If none of the ires have been disconnected, remove the ires connected to the run capacitor.
4. Measure the capacitance of the run capacitor:
•Model 1710A/1750A – 55 microfarad ± 5%
•Model 1770A – 60 microfarad ± 5%
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1710A/1750A/1770A Parts List

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