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Building AutomationIntermediate 15-45 minutes
Unit will not power on
Reported Symptom
Unit will not power on
Safety Warnings
- •High voltage may be present inside the unit.
- •Do not bypass fuses or safety devices.
- •Call a licensed professional for internal live electrical diagnosis.
Possible Causes
- 1No incoming power
- 2Open disconnect or tripped breaker
- 3Blown control fuse
- 4Loose field wiring
- 5Failed control board or transformer
Tools Required
- Multimeter
- Non-contact voltage tester
- Insulated screwdriver set
- Wet/dry vacuum
- Brush
- Bucket
Parts Required
- Drain tubing
- Drain fittings
- Lamp
- LED driver
- Photocell
- Ballast
Diagnostic Steps
1
Confirm the complaint and note any error lights or display messages.
2
Verify the equipment disconnect is on and check for a tripped breaker or blown fuse.
3
Check for proper incoming voltage at the line side using site-safe procedures.
4
Verify control voltage is present where applicable and inspect wiring terminals for loose or burned connections.
5
If power is present but the unit remains inactive, stop at component-level live testing and escalate to a licensed technician.
Solution
Recommended Resolution
- Restore power, reset the breaker once if appropriate, or replace the blown fuse with the correct rating.
- Tighten or repair damaged field wiring per manufacturer guidance.
- If the control transformer, board, or internal electrical component has failed, have a licensed technician replace and recommission the unit.