Manual for CLASSIC 90 PLUS - Troubleshooting and error codes + PDF Download

Manual for CLASSIC 90 PLUS - Troubleshooting and error codes + PDF Download

Brand: Rheem

Category: Furnace

Document Type:

Language: EN

Uploaded: April 8, 2025, 1:45 p.m.

Manual Publish Date: 2009-10-01

Warranty Summary

Rheem provides a limited lifetime warranty on the primary and secondary heat exchanger and a ten (10) year warranty on conditional parts (with registration).
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The Rheem Classic® 90 Plus High Efficiency line of downflow/horizontal gas furnaces are designed for utility rooms, closets, alcoves, attics or crawl spaces. Key features include:

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  • Stainless steel heat exchanger for corrosion resistance and thermal fatigue reliability.
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  • Low profile "34 inch" design for easier handling.
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  • Integrated control board for operational functions and hookups for humidifier and electronic air cleaner.
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  • Insulated blower compartment and slow-opening gas valve for quiet operation.
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  • Pre-paint galvanized steel cabinet and molded permanent filters.
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Troubleshooting and error codes

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ProblemPossible Cause
No HeatNo gas supply, pilot light outage, thermostat malfunction
Blower runs constantlyThermostat in 'fan on' mode, limit switch issue
Furnace cycles too frequentlyDirty filter, incorrect thermostat setting, undersized furnace
Unusual noisesLoose blower wheel, ductwork issues, burner problems
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