Tempstar Transformer for T9MPV050F12D1 — 40VA 115V to 24V | Ships Today

Overview

This OEM 40VA control transformer (part #1172810) powers the low-voltage control circuit of your Tempstar T9MPV050F12D1 gas furnace, stepping 115V line voltage down to the 24V used by the control board, gas valve, igniter circuit, and thermostat. A failed transformer cuts power to the entire control system: the thermostat goes dark, the furnace ignores heat calls, and the ignition sequence never starts. Telltale signs include a blown low-voltage control fuse, a humming transformer, or no voltage across the 24V secondary terminals. At 40VA it carries the full control load of this variable-speed furnace with margin to spare.

Specifications

Compatibility

Direct OEM replacement for the Tempstar T9MPV050F12D1 variable-speed gas furnace. The same 115V-to-24V 40VA transformer is used across many ICP-family furnaces (Tempstar, Heil, Comfortmaker). Verify the part number against your existing unit before installing.

Installation Guide

1. Safety First — Disconnect power at the furnace switch and breaker. Verify zero voltage with a multimeter at the transformer terminals.
2. Access — Remove the furnace control-compartment service panel.
3. Document — Photograph all primary and secondary wire connections before disconnecting.
4. Remove — Disconnect the line and 24V leads, then unbolt the failed transformer from its bracket.
5. Install — Mount the new transformer and reconnect leads exactly per your photo.
6. Test — Restore power, confirm 24V across the secondary, and run a complete heat cycle.

Signs You Need a Replacement

• Blank thermostat and no furnace response to a heat call
• Repeatedly blown control-board fuse
• Audible buzzing or humming from the transformer
• No 24V reading at the secondary terminals

Shipping & Returns

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