Furnace will not start at all, no lights on the Danfoss controller, blower and burner inactive

Safety first: Turn off the breaker before opening electrical compartments. Use a non-contact voltage tester if available.

Steps:

• Check breaker and switch: Verify the furnace breaker is ON and the furnace service switch is in the ON position.
• Inspect internal fuse: Many Danfoss controls have an internal low-voltage fuse. With power off, remove and visually inspect the fuse. Replace only with the same type and rating.
• Check door interlock: Ensure the blower door is properly installed to engage any door switch.
• Verify transformer output: A technician can measure the low-voltage transformer output to confirm it is supplying the control.