Trane SCXG-SVX01B-EN Maintenance diagnostics, Supply Fan Failure, Supply Fan VFD Bypass Enabled

Maintenance diagnostics

SupplyAirTemp Cool Setpoint Fail Problem: The active supply air temperature cooling setpoint is out of range.

Reason for Diagnostic: The input designated as the SA temp cooling setpoint is out is out of range (temp < 35°F or temp > 95°F).

UCM Reaction: The default HI-set SA temp cooling setpoint becomes the active SA temp cooling setpoint.

Reset Required: (PAR) An automatic reset occurs after the SA temp cooling setpoint input returns to within range for 10 continuous seconds, or after a different SA temp cooling setopint selection source is user-defined.

Supply AirTemp Heat Setpoint Fail Problem: The active supply air temperature cooling setpoint is out of range.

Reason for Diagnostic: The input designated as the SA temp heating setpoint is out is out of range (temp < 35°F or temp > 185°F).

UCM Reaction: The default HI-set SA temp heating setpoint becomes the active SA temp heating setpoint.

Reset Required: (PAR) An automatic reset occurs after the SA temp heating setpoint input returns to within range for 10 continuous seconds, or after a different SA temp heating setopint selection source is user-defined.

Supply Air Temperature Failure Problem: The supply air temperature sensor input is out of range.

Check: Sensor resistance should be between 830 ohms (200°F) and 345.7 ohms (-40°F). If so, check field/unit wiring between sensor and RTM.

Reason for Diagnostic: The unit is reading a signal that is out of range for the supply air temperature input on the RTM (temp. < -55°F or temp > 209°F).

UCM Reaction:These unit functions are disabled:

•supply air tempering

•economizing

•supply air temperature low limit function (CV units)

•supply air temperature control heating and cooling functions (VAV units)

Reset Required: (PAR) an automatic reset occurs after the designated S/A temperature input returns to its allowable range.To prevent rapid cycling of the diagnostic, there is a 10 second delay before the automatic reset.

Supply Fan Failure

Problem: There is no supply airflow indication after the supply fan is requested on.

Check: Check belts, linkages, etc. on the supply fan assembly. If these are ok, check field/unit wiring between RTM and supply fan. If the supply fan runs in service mode, then verify airflow proving switch and wiring.

Reason for Diagnostic: The supply airflow input is detected OPEN for 40 continuous seconds during any period of time in which the supply fan binary output is ON. between 830 ohms (200°F) and 345.7 ohms (-40°F). If so, check field/unit wiring between the sensor and MCM.

This input is ignored for up to 5 minutes after the supply fan starts, until airflow is first detected.

UCM Reaction: “Off” or “Close” requests are issued as appropriate to the following functions;

a. Compressor staging/chilled water control

b. Heat operation

c. Supply fan control & proof of operation d. Exhaust fan control & proof of operation e. Exhaust actuator control

f. Economizer actuator control g. IGV / VFD control

Reset Required: (PMR) A manual reset is required anytime after the diagnostic is set. The diagnostic can be reset at the HI, Tracer Summit, or by cycling power to the RTM.

Supply Fan VFD Bypass Enabled

a. Data used (module,packet,byte,bit): RTM

b. Activation conditions: supply fan VFD bypass has been activated and supply fan vfd bypass is installed.

c.Time to React: 10 sec <T < 20 sec

d. Diagnostic text (human interface display)

SUPPLY FAN VFD BYPASS ENABLED” e. Actions to be Initiated: NONE

f. Reset: The INFO diagnostic is cleared when the supply fan VFD bypass is deactivated.

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LCI-I Module Comm Failure

Problem: The RTM has lost communication with the LCI-I.

Check: Check field/unit wiring between RTM and LCI-I module.

Reason for Diagnostic: The RTM has lost communication with the LCI-I module.

UCM Reaction: All active commands and setpoints provided byTracer Summit through the LCI-I will be cancelled and/or ignored. And whereTracer Summit has been designated as setpoint source, local HI default setpoints will be used.

Reset Required: (PAR) An automatic reset occurs after communication has been restored.

Tracer Communications Failure

Problem:The LCI-I has lost communication withTracer Summit.

Check:Tracer Summit(building control panel) is powered up and running properly. If so, check unit wiring between LCI-I and Tracer Summit (building control panel).

Reason for Diagnostic:The LCI-I has lost communications withTracer Summit for > 15 minutes.

UCM Reaction: All active commands and setpoints provided byTracer Summit through the LCI-I will be cancelled and/or ignored. And whereTracer Summit has been designated as the setpoint source, local HI default setpoints are used.

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