Ruud 47-104990-03 Gas Furnace Limit Switch Auto Reset

Product Description

The RUUD 47-104990-03 is a single-pole, normally closed, auto-reset limit switch designed for gas furnace overheat protection. It opens at 170 degrees F and resets automatically when the temperature drops back to 150 degrees F, interrupting the burner circuit before heat exchanger temperatures reach damaging levels. Rated for 120/230 VAC at 15/10 amps, this SPST switch is a direct OEM-style replacement. The blue color coding and 3-inch insert dimension allow for correct identification and positioning during service. Licensed HVAC technicians perform this replacement as part of routine furnace diagnostics and safety-system maintenance.

This limit switch is used in residential gas furnace applications where thermal overheat protection is required in the heat exchanger or plenum area. It is specifically listed for use on the R801PA075317MSA and R801PA075317MXA gas furnace models. The auto-reset design eliminates the need for manual reset after a single overheat event, though repeated tripping should prompt a full system diagnostic to identify the root cause before returning the unit to service.

Key Features

• Opens at 170 degrees F, closes at 150 degrees F for reliable overheat protection
• Auto-reset operation restores circuit continuity once temperatures normalize
• SPST, normally closed, 1-pole configuration for standard furnace limit circuits
• Dual voltage rating: 120/230 VAC at 15/10 amps respectively
• 3-inch insert dimension for correct fitment in the furnace heat exchanger collar
• Blue color coding aids identification and correct part matching during service

Compatibility

Listed for use on the RUUD R801PA075317MSA and R801PA075317MXA gas furnace models.

Installation Notes

Installation should be performed by a licensed HVAC technician. Shut off all power to the furnace at the disconnect and turn off the gas supply before removing the existing switch. Verify the insert length and temperature ratings match before installing the replacement. Repeated limit trips after replacement indicate an airflow or heat exchanger issue that must be diagnosed before the system is returned to service.

Technical Specifications

• Switch Type: SPST, Normally Closed, Auto Reset, 1-Pole
• Open Temperature: 170 degrees F
• Close Temperature: 150 degrees F
• Voltage Rating: 120/230 VAC
• Amperage Rating: 15/10 amps
• Insert Length: 3 inches
• Color: Blue
• Overall Length: 5.45 inches
• Width: 3.05 inches
• Height: 2.05 inches
• Weight: 0.08 pounds

Standard Information

• Brand: RUUD
• Manufacturer Part Number: 47-104990-03