Greenheck Fan Make-Up Air Unit VSU - Manual (Page 14)

14 Model VSU Make-Up Air
® ® ® ® ®
115 VAC between
terminals 102 and 101?
Check Main Voltage
(See Blower Start-Up Step #1)
Main Disconnect (DS1) Off
(Turn Main Disconnect DS1 On)
Primary Fuses Blown
(Replace Fuses)
Main Transformer Defective
(Replace Transformer) 24 VAC between
terminals R and X?
Main Transformer Defective
(Replace Transformer)
24 VAC between
terminals G and X?
Supply Switch (S2) Off
(Turn Supply Switch (S2) On)
No
No
No
No
Yes
Yes
Yes
Yes
Blower Does Not Operate
Broken Fan Belt
(Replace - Reference Maintenance section)
Defective motor or capacitor
(Repair/Replace)
Blown Motor Fuse
(Replace)
One or more legs of 3 phase is out
(Restore missing legs)
24 VAC between
terminals 7 and X?
Damper Limit Switch (DL1) Holding
(Wait for actuator to open fully or adjust limit switch)
Troubleshooting
At this time the supply should be energized., passing
power to the supply motor and the blower should start.