Table 5 – Troubleshooting Guide - Aprilaire 1870 Installation Instructions Manual

TROUBLESHOOTING
TABLE 5 – Troubleshooting Guide
Symptom Possible Reason
Dehumidifier does not No power to unit .
turn on/run .
Dehumidifier blower is Pressure drop across
running but with little or dehumidifier is higher
no airflow . than 0 .6"w .c .
Dehumidifier blower is Float switch open .
running but compressor
is not .
Coil frosting .
DEFROSTING will be
displayed on control
screen .
Inlet air temperature is
outside of the 50°F –
104°F range or the dew
point is below 40°F and
there is a demand for
dehumidification .
When zoned, the Incorrect damper wiring
dehumidifier damper or bad connection .
does not open in
INSTALLER TEST mode .
The ventilation damper Cycle time has been
does not open when the met .
HVAC fan is active .
ODT error or outdoor air
outside of ODT range .
Dehumidifier is not Drain line blocked or unit
draining properly . not level .
The HVAC fan turns on Dehumidifier is sampling
unexpectedly . or ventilation in
progress .
Dehumidifier is Normal function .
producing hot air .
26
(CONTINUED)
Troubleshooting Procedure
• Check that the dehumidifier is plugged in .
• Check that the power switch is turned ON .
• Check that the control is turned ON .
• Check that the circuit breaker has not tripped .
• Check dehumidifier air filter and wash or replace .
• Check for blocked duct work and clear .
• Verify that the outlet collar with backflow damper is installed on the outlet side of the dehumidifier .
• Check if backflow damper is blocked or stuck and remove obstruction .
• If float switch installed, check connections at control board and empty condensate pan .
• If no float switch installed check that the jumper is installed at the float switch terminals on the
control board .
• Lack of or reduced airflow . Check dehumidifier air filter and wash or replace .
• Check for blocked duct work .
• Inlet air conditions below 60°F . Increase the humidity setting .
• Verify all ductwork is properly sealed .
• Verify wiring between dampers and 24 VAC transformer .
• If wired for Two Zone operation, verify that 24 VAC transformer is 40 VA minimum .
• Check all wiring connections between dampers and control board .
• Verify the normally closed dampers are in the Primary Zone ductwork and the normally open
dampers are in the Secondary Zone ductwork .
• The damper will not open if the Ventilation Time has already been met .
• Check that the ODT is wired correctly to the
dehumidifier control board and connections are secure .
• Check that the ODT is installed in the outdoor air
intake according to the set-up specified in the
Ventilation Section beginning on page 19 .
• Remove the ODT leads from the dehumidifier control
board and check the resistance . Compare the reading
with the table shown .
• Verify that the unit is level .
• Check the drain line blockages and for a continuous downward slope .
• The dehumidifier will turn on the HVAC fan during air sampling or as needed to meet the ventilation
time .
• Air is reheated across the condenser coil, resulting in a temperature rise between inlet and outlet .
Outdoor
Resistance
Temperature
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