What does Miller code 3 Blinks mean?
Miller furnace code 3 Blinks means the pressure switch was stuck open when it should have closed on the supported control family. Confirm the model number and diagnostic chart inside the furnace door before replacing parts.
What causes Miller code 3 Blinks?
- A blocked intake or exhaust vent
- A restricted condensate drain or pressure hose
- A weak inducer motor or pressure switch
Can I troubleshoot Miller code 3 Blinks?
- With the furnace off, check outdoor intake and exhaust openings for snow, ice, leaves, or nests.
- Replace a visibly dirty air filter, restore power once, and note whether the code returns.
How much does Miller code 3 Blinks cost to fix?
A pressure switch replacement typically costs between $175 and $900 nationally.
When should I call a technician?
Call a technician if the vent is clear and the pressure-switch code returns; combustion-air testing requires instruments.
Sources and model scope
Fault codes vary by model and control board. Confirm the diagnostic chart inside your furnace panel or the official manual before acting.
Scope used here: Nortek single-stage condensing furnaces using the documented Emerson integrated control.
- Nortek Global HVAC: Single Stage Condensing Gas Furnaces — Installation Instructions
1041594D · Nortek single-stage condensing gas furnaces using the documented Emerson integrated control; manufactured-home models and older boards may differ.
Compiled by Warmlo Editorial · Reviewed August 2026
This is general information, not professional advice. Gas, electrical, and combustion repairs can be dangerous — when in doubt, call a licensed technician.