39
0
6/16 - Subject to change. © Belimo Air
controls
(USA
), Inc
.
Fault Detection
Problem
Diagnostic Action
(in addition to alarm stored / transmitted)
Potential Cause
CA Fault
Code
RAH sensor
detected but
OAH sensor
not detected
Sensor previously
installed is not detected
or sensor has not been
installed -
Differential Enthalpy
• Economizing functioning by differential
temperature with return air humidity limit
• Intended configuration of differential enthalpy
not completed or OAH sensor failed
• Intended configuration of single enthalpy,
OAH sensor inadvertently placed on RAH
terminal
• OAH sensor deleted or set to not installed, but
RAH sensor left installed
A, B
RAH sensor
detected but
RAT sensor
not detected
Sensor previously
installed is not detected
or sensor has not been
installed -
Differential Enthalpy
• Economizing functioning by OAE single enthalpy
• Change over limit modified to 28 Btu/lb 75°F
• Intended configuration of differential enthalpy
not completed or RAT sensor failed
• RAT sensor deleted, but RAH sensor left
installed
A, B
SAT sensor
out of range
Sensor is returning a
value that is out of the
predetermined range
• Economizing functionality disabled
• Freeze detection based on OAT only
• Low discharge limit control 45°F disabled
• Compressor SAT drop error detection disabled
• Limiting 2nd stage operation based on low SAT
(SAT Y2 limit) disabled
• Thermistor failure
• Damage to wire increasing resistance
A, B
SAT sensor
not detected
Sensor previously
installed is not detected
or sensor has not been
installed
• Economizing functionality disabled
• Freeze detection based on OAT only
• Low discharge limit control 45°F disabled
• Compressor SAT drop error detection disabled
• Limiting 2nd stage operation based on low SAT
(SAT Y2 limit) disabled
• Sensor never installed
• Installed sensor has open or short
• Wire harness broken
A, B
Y2 present
without Y1
Call for Y2 without call
for Y1
• Enable 1st stage free cooling or mechanical
cooling in accordance change over
configuration
• If Y1 follows Y2, 2nd stage integrated or
mechanical cooling will be enabled
• Miswired or reverse wired thermostat
• Miswired ZIP Economizer
• Thermostat failure
• Wire harness broken
N/A
SAT drop for
CC1 or CC2
insufficient
SAT sensor determined
that temperature
downstream of
evaporator did not drop
by at least 5°F after 4
min of CC1 or CC2 being
energized
• Informational only - no action
• Filters or coils are dirty or blocked – inspect
• SAT sensor in a location where it is not mixed
- perform temperature traverse
• Indoor fan is inoperable -
check relay, belt, motor, bearings
• Condenser fan is inoperable -
check relay, motor, head pressure control
• Compressor is faulty (internal damage) -
check amperage, pressures
• Contactor energizes but compressor is off on
internal/external overload
• High voltage problem to compressor -
check wiring, phases, contactor
• Low on refrigerant - check charge
N/A
Damper Pos
value missing
Economizer is not
sensing feedback from
actuator
• Logic reconfigured to use setpoint as reference
for items dependent on actual position
(i.e. integrated cooling)
• Damper stuck fault detection capability is
disabled
• Actuator wires not properly terminated
• Actuator without feedback capability used
• Wire harness broken
• Actuator electronic failure
E
SAT should
be lower
When damper is greater
than 85% open, and in
free cooling, SAT sensor
determined that
temperature is not within
10°F of OAT
• Informational only - no action
• Damper linkage failure
• Actuator clamp / interface between damper
is not secure
• Damper blades are not secured to damper
shaft properly
• Outside air damper and return damper do not
stroke properly
• Return damper does not closes tightly when
outdoor damper is full open
• OAT sensor is poorly located
• SAT sensor is poorly located
B
Damper is
stuck
Feedback signal is not
within range of
commanded position
• If rotation is less than 85%, then integrated
cooling will be disabled
• Damper linkage failure
• Damper blocked with foreign object
• Actuator limit stop engaged
• Damper rotation has not been scaled using
Economizer Acceptance Test
B, C, D, E
ZIP Economizer
Fault Detection and Diagnostics (FDD) Table
