What It Means
Low pressure switch open while inducer runs at high speed.
Rheem Furnace
Rheem Furnace Error Code 45
Troubleshooting guide for the Rheem Furnace system fault 45.
Possible Causes
- Blocked or restricted intake/exhaust vent.
- Excessive vent length or elbow restrictions.
- Failed inducer motor or control relay.
- Blocked pressure switch tubing or bad switch.
Not sure which one it is — or if it's none of these? Try ACLogics today.
Disclaimer: This information is for general reference. Error codes can vary by model and production year. Always refer to your machine's specific manual and the information printed on the unit itself.
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Full Diagnosis
Low pressure switch open while inducer is running at high speed.
All Recorded Causes
Blocked or improperly terminated intake/exhaust vent, excessive vent length or elbows, failed/disconnected inducer, faulty inducer relay/control board, loose wiring, blocked/split pressure-switch tubing, wind effects, or faulty pressure switch.
Verify Before Replacing Parts
- Confirm the exact Rheem model family and furnaces context before acting on a generic code description.
- Walk the entire heating sequence in order instead of jumping straight to the reported code, watching for blocked or improperly terminated intake/exhaust vent, excessive vent length or elbows, fai….
- Verify each safety device and prove where the sequence stops under live operation, including whether the next candidate on the list.
- After the correction, run the system long enough to confirm the furnaces fault does not return under normal load.
Still unsure about this fault?
ACLogics walks you through Rheem Furnace diagnostics step-by-step — so you confirm the cause before swapping parts.
