Tempstar 40VA Transformer for T8MPV075F14B1 — 115V to 24V Control Transformer | Ships Today

Overview

This is a genuine OEM 40VA control transformer (Part No. 1172810) for the Tempstar T8MPV075F14B1 furnace. It steps 115V line voltage down to the 24V low-voltage control power that drives the thermostat, gas valve, igniter relay, and control board. When this transformer fails, the entire 24V control circuit goes dead and the furnace stops responding to thermostat calls for heat. Typical symptoms include a completely unresponsive furnace, a blank thermostat, a buzzing or overheating transformer, a repeatedly blown low-voltage fuse, or a scorched transformer body. Its 40VA rating provides ample capacity for the control loads on this model.

Specifications

Compatibility

Engineered as a direct OEM fit for the Tempstar T8MPV075F14B1 gas furnace. This 115V-to-24V 40VA transformer is shared across numerous ICP-family furnaces under the Tempstar, Heil, Comfortmaker, and Arcoaire brands. Confirm your existing unit is a 115V primary / 24V secondary 40VA transformer before ordering.

Installation Guide

1. Safety First — Disconnect power at the furnace switch and breaker, then verify zero voltage with a multimeter before touching any wiring.
2. Access — Remove the furnace control/blower service panel to expose the control box.
3. Document — Photograph all primary and secondary wire connections before disconnecting anything.
4. Remove — Label and disconnect the 115V primary leads and 24V secondary leads, then unbolt the failed transformer from its bracket.
5. Install — Mount the new transformer, reconnect the primary and secondary wiring exactly per your photo, and confirm all connections are tight.
6. Test — Restore power, call for heat, and verify 24V on the secondary and normal furnace startup with your multimeter.

Signs You Need a Replacement

• Furnace is completely unresponsive to thermostat calls for heat.
• Thermostat screen is blank or loses power.
• Repeatedly blown low-voltage (24V) fuse on the control board.
• Transformer is hot, buzzing, swollen, or shows burn marks.

Shipping & Returns

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