Issue

Potential Cause

Solution

No power

The breaker in the building breaker panel is off or tripped.

Turn the breaker on or reset and turn on.

Unit disconnect switch is in the OFF position.

Change the disconnect to the ON position.

Onboard circuit breaker CB-01 is in the OFF position.

Change the breaker switch to the ON position.

Issue

Potential Cause

Solution

HMI Communication Fault

The Space HMI is not connected.

If a Space HMI is present, ensure there is a CAT-5 cable connected between the Space HMI and the onboard HMI in the unit.

Take the Space HMI to the unit and try connecting it with a short CAT-5.  This will tell you if the issue is with the CAT-5 cable.

The HMI Modbus Address is not set correctly.

Press both bottom buttons on the HMI at the same time.

The Modbus Address for the onboard HMI should be set to 55.

The Modbus Address for a single Space HMI should be set to 56.

If applicable, additional Space HMIs should be set to 57, 58, 59, etc.

The unit is configured for the incorrect number of HMIs.

Make sure the unit is configured for the correct number of HMIs.

This is found under

Factory Settings > Unit Options > Board Config > HMI Config > Number

CAT-5 cable and/or low voltage circuit is damaged.

Try a different CAT-5 cable.

Remove all low voltage connections from the MUA Board and plug back in one at a time to isolate the short.

If none of the above solutions correct the issue, the printed circuit board (MUA Board) may need to be replaced.

An on-site technician will need to contact technical support for troubleshooting.

Technical Support is available Monday through Friday from 8 AM to 8 PM EST.

Please submit a support ticket for additional assistance.

Issue

Potential Cause

Solution

Blower not running, no airflow

No power to unit.

See No power section above.

Intake damper end limit switch is not closed.

Make sure the intake damper is open.

Make sure there is 120 VAC present across terminals IEL and N.

Check the Intake Damper setting and ensure that it is set to ON.

This is under Factory Settings > Unit Options > Intake Damper.

Blower Control not set correctly

Ensure that Blower Control is set correctly for the application and sequence of operation. Blower control may be local, through interlock, or through a building management system.

This is under Factory Settings > Unit Options > Blower Config > Blower Control.

Blower Mode not set correctly.

Ensure that Blower Mode is set correctly for the application and sequence of operation.

This is under Factory Settings > Unit Options > Blower Config > Blower Mode.

Unit has not been turned on via the HMI.

If the unit is designed to be turned on and off via the HMI, ensure that the Unit On button has been pressed.

The text on the HMI is a command and not a status. This means that if the HMI displays Unit On beside the bottom left button, the button needs to be pressed to turn the unit on.

Issue

Potential Cause

Solution

Low PS Fault

Profile pressure is less than low profile pressure setpoint, but greater than lower pressure limit (0.05” w.c.).

Adjust profile pressure.

Factory Settings > Unit Options > Blower Config > Air Profile Limits.

Increase blower speed.

Blower not running.

See Blower not running section above.

Blower speed too low.

Increase fan RPM. 

Do not overload the motor.

Fan rotation is incorrect.

Check fan rotation and correct if needed.

Intake damper not open.

Check for 120 VAC across DM and N. If 120 VAC is present, check for 120 VAC across IEL and N to ensure that the damper end limit switch is closed.

Visually inspect the damper to make sure it is open.

Make sure the damper blades are not in a bind and/or jammed.

Onbd Prof PS is not within range.

Ensure that the burner differential pressure is between .15” and .8” w.c. With the blower running, this can be monitored under

Service > Variable Values > Inputs > Onbd Prof PS.

If Onbd Prof PS is not reading between .15” and .8” w.c., the onboard pressure transducer can be calibrated. Disconnect the airflow tubing from the aluminum pitot tubes.

On the HMI, go to

Service > Calibrate Onboard PS and start the calibration.

If the Onbd Prof PS reading is not between .15” and .8” w.c. after calibration is complete, there may be an issue with the onboard pressure transducer.  Please contact technical support at 866.784.6900 – Option 3.

Airflow tubing has moisture in it, is damaged, clogged, disconnected, etc.

Duct static pressure is higher than design.

Check ductwork. Adjust/resize to eliminate or reduce duct losses.

Intake filters are dirty and/or clogged.

Clean or replace intake filters.

Perforated supply plenum (if applicable) perf sections are dirty and/or clogged.

Remove perf sections and inspect for cleanliness/clogs.  Clean as needed.

Supply grills or registers are closed.

Open and/or adjust.

Blockage in duct work.

Inspect supply duct(s) for blockages, collapse, closed dampers, etc.