Pressure Switch Error
Common to All Furnace Brands
Furnace Not Starting?
778-909-5731What is a Pressure Switch Error?
The pressure switch is a critical safety device that confirms proper airflow through your furnace before allowing it to ignite. When this error occurs, the pressure switch is either not closing (proving insufficient draft) or not opening when it should.
This error appears under different names depending on your furnace brand:
- Lennox: E227
- Carrier: Code 33 or 13
- Trane: 3 flashes
- Goodman: 3 flashes
- York: 3 flashes or Code 12
Common Causes
- Blocked Venting: Exhaust pipe blocked by ice, debris, or animal nests
- Clogged Drain: Condensate drain blocked causing water backup
- Failed Inducer Motor: Draft inducer not creating sufficient vacuum
- Bad Pressure Switch: Switch itself has failed
- Disconnected Pressure Hose: Small hose to switch is loose or damaged
Quick Checks You Can Do
Safe troubleshooting steps
- Check exhaust pipe outside: Look for ice buildup or blockages at the exhaust termination
- Inspect air intake: Ensure nothing is blocking the fresh air intake pipe
- Check furnace filter: A severely clogged filter can affect pressure readings
- Look for water: Check if there is water pooled around the furnace
Professional Diagnosis Required
Pressure switch errors require expert diagnosis. Our technicians will:
- Test inducer motor operation and vacuum levels
- Inspect and clear venting system
- Test pressure switch functionality
- Clear condensate drain system
- Verify proper venting installation
Brand-Specific Error Code Pages