Tempstar Transformer for T9MPD050F12A1 – 40VA 115V to 24V | Ships Today

Overview

This OEM 40VA control transformer (part #1012722) converts the incoming 115V line voltage to the 24V control voltage that runs your Tempstar T9MPD050F12A1 gas furnace. It supplies power to the thermostat circuit, ignition control board, gas valve, and relays. A failed control transformer takes down the entire low-voltage system: the thermostat may go blank, the furnace won't respond to a heat call, and the board's low-voltage fuse may blow repeatedly. Buzzing, a burnt smell, scorched windings, or zero volts on the 24V secondary all point to replacement. This direct-fit factory unit is rated at 40VA with a 115V primary and 24V secondary.

Specifications

Compatibility

Engineered for the Tempstar T9MPD050F12A1 gas furnace and shared across many ICP/Heil/Comfortmaker furnace platforms using a 40VA 115-to-24V control transformer. Confirm primary voltage and VA rating against the failed unit before installing.

Installation Guide

1. Safety First – Disconnect power at the furnace switch and breaker, then verify zero voltage with a multimeter.
2. Access – Remove the furnace control/blower compartment service panel.
3. Document – Photograph all primary and secondary wire connections before disconnecting.
4. Remove – Disconnect the primary (line) and secondary (24V) leads, then unbolt the transformer from its bracket.
5. Install – Mount the new transformer, reconnect the primary and secondary leads exactly per your photo, and secure all terminals.
6. Test – Restore power, verify 24V across the secondary terminals, and confirm the furnace responds to a heat call.

Signs You Need a Replacement

• Blank thermostat and no response to a call for heat
• Repeatedly blown low-voltage (3A) control board fuse
• Zero or low voltage across the 24V secondary terminals
• Audible buzzing, burning smell, or scorched windings

Shipping & Returns

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