Amana AMVM970803BN Error Code EE9: High Stage Pressure Switch Not Closed
What Does Code EE9 Mean?
Error code EE9 on the Amana AMVM970803BN indicates that the high stage pressure switch circuit is not closing. The furnace can still operate on low stage (reduced capacity), but it cannot fire at high stage. The induced draft blower is running, but the pressure differential is not high enough to satisfy the high stage pressure switch.
This modulating furnace uses separate pressure switch setpoints for low and high stage operation. The high stage pressure switch requires a stronger draft because the furnace produces more combustion gases at higher firing rates. When the switch does not close, the control module limits the furnace to low stage operation only, which means reduced heating capacity.
Common causes include a partially blocked flue or intake pipe that restricts airflow enough to prevent the higher draft needed for high stage. A blocked or kinked pressure switch hose, a clogged condensate drain backing water into the inducer housing, or a weak induced draft blower can also prevent the high stage switch from closing. Since the furnace still heats on low stage, this issue may go unnoticed until very cold weather demands full capacity.
Common Causes
When to Call a Professional
Contact a licensed HVAC technician if:
- EE9 persists after clearing the flue, intake, and condensate drain
- The induced draft blower sounds weak or makes unusual noises at high speed
- The pressure switch hose appears damaged or the connections are deteriorated
- The furnace cannot keep your home warm during very cold weather (stuck on low stage)
- Water is backing up in the inducer housing despite a clear drain line
✓ Verified against manufacturer service manual — March 2026