Carrier 40UV - Page 71

71
Table 30 — Unit Diagnostics and Troubleshooting (cont)
LEGEND
PROBLEM POSSIBLE CAUSE CORRECTIVE ACTION
Indoor Air Quality (IAQ)
Features Malfunctioning
IAQ not enabled Enable IAQ control operation.
Set point too high/too low Adjust the set point to the correct value.
Space or return air temperature too high/low Control will resume when space/returns temperatures
recover.
Space Relative Humidity too high Control will resume when relative humidity recovers.
Verify high humidity limit is configured properly. Reset to
100% if RH control is not used.
MAT sensor is shorted, open, or forced Normal operation will resume when MAT sensor is
operating properly. Remove Force; repair or replace MAT
sensor.
LLT Trips Frequently LLT switch malfunctioning Replace LLT switch.
MAT sensor failed or out of calibration Verify MAT sensor is reading correctly. Trim or replace if
necessary.
IAQ Level Exceeds
Set Point Frequently
(Generated Alarms)
Maximum output value set too low Verify maximum output value has been correctly set.
Increase value in 10% increments.
OAT sensor failed or open Normal operation will resume when OAT sensor is
repaired.
DX — Direct Expansion
IAQ — Indoor Air Quality
LED — Light Emitting Diode
LLT — Low-Limit Thermostat
MAT — Mixed-Air Temperature Sensor
MIX1 — Mixed Air 1Terminal
MIX2 — Mixed Air 2 Terminal
OA — Outdoor Air
OAT — Outdoor-Air Temperature Sensor
RH — Relative Humidity
RAT — Return-Air Temperature
SPT — Space Temperature Sensor
TB — Terminal Box