Tempstar Control Transformer for T9UHX080J12A1 — 40VA 115V to 24V | Ships Today

Overview

This is the OEM low-voltage control transformer (OEM part 1172810) for the Tempstar T9UHX080J12A1 gas furnace. It steps 115V line voltage down to the 24V control voltage that powers the thermostat, integrated control board, gas valve, igniter circuit, and relays. Rated at 40VA, it delivers enough current to drive the complete low-voltage control circuit. A failed transformer leaves the furnace completely dead — no thermostat display, no blower, no ignition sequence — even with line power present. Common failure signs include a repeatedly blown low-voltage fuse, a buzzing or scorched transformer body, or an open winding when tested with a multimeter.

Specifications

Compatibility

Direct-fit replacement for the Tempstar T9UHX080J12A1 furnace and compatible ICP/Heil/Comfortmaker variants using the 1172810 transformer. Always match the VA rating and primary/secondary voltages to your original part before installing.

Installation Guide

1. Safety First — Disconnect power at the furnace switch and breaker, then verify zero voltage at the transformer leads with a multimeter.
2. Access — Remove the furnace blower/control compartment service panel.
3. Document — Photograph all primary and secondary wire connections before disconnecting anything.
4. Remove — Disconnect the 115V primary leads and the 24V secondary leads, then unbolt the transformer from its bracket.
5. Install — Mount the new transformer and reconnect the primary and secondary wiring exactly per your photo.
6. Test — Restore power and confirm 24V on the secondary plus normal thermostat operation.

Signs You Need a Replacement

• Furnace is completely unresponsive with no 24V control power present.
• Repeatedly blown low-voltage control fuse.
• Transformer is hot, buzzing, or smells burnt.
• Multimeter shows an open or shorted winding.

Shipping & Returns

Ships same day before 3 PM CST. 30-day returns. Backed by the National HVAC Parts fitment guarantee.