The A29/A30 alarm only applies to DC powered supply fans. If this alarm is displayed when AC fans are installed, change the SF1 setting in the D menu from 0 to 1 or from AUT/DC to AC. If using the PGD, change option Ch1 in the Manufacturer Menu to AC. See Chapter 1: Model Identification to determine supply fan power input.

When the DC fan is running, pressure is built up across the air pressure differential switches (PF2 & PF3) and the circuit between terminals 5 & 9 will close. If the pressure switch does not close after 60 seconds, A29/30 will trigger, indicating problems with the supply fan.


Possible Cause
Component to Check
Recommended Action
No power to DC fan
Verify 48VDC presence on DC breaker. Verify 48VDC across 12 and 131 to the supply fan
Correct DC power supply.
Incorrect DC polarity
Placing the red probe on the +48 terminal and the black probe on the -48 terminal should give a +48VDC reading. Verify controller side as well.
Correct DC polarity.
No speed signal to DC fan
Speed signal between 11 and 12.
Verify 0-10 VDC signal between terminal 11 and 12.
Incorrect alarm wiring
Alarm wiring
Verify wiring. See DC Fan Air Flow Alarm Wiring.
Faulty air pressure differential switch
Air pressure differential switch should close when the fan is running at high speed
Replace air pressure differential switch.

DC Fan Air Flow Alarm Wiring