Tempstar Transformer for T9MPV100J20B1 — 115V to 24V 40VA | Ships Today

Overview

This OEM control transformer (part #1012722) converts 115V line voltage to 24V for the low-voltage control circuit of the Tempstar T9MPV100J20B1 gas furnace. Rated at 40VA, it powers the integrated furnace control board, thermostat, gas valve, and safety circuits with clean, stable 24VAC. When this transformer fails, the entire 24V control system loses power — the furnace ignores thermostat calls, the control board goes dark, and no components energize. Typical failure modes include a shorted secondary winding, a control-circuit overload, a voltage surge, or normal age-related winding breakdown. Replacing it with the correct 40VA OEM transformer restores full control power and shields downstream parts from voltage irregularities.

Specifications

Compatibility

Designed as a direct-fit replacement for the Tempstar T9MPV100J20B1 modulating variable-speed gas furnace. This 115V-to-24V 40VA transformer is common across ICP-family furnaces (Tempstar, Heil, Comfortmaker, Arcoaire) sharing the same control-power requirement. Confirm your existing unit is rated 115V primary / 24V secondary at 40VA 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 (line) and secondary (24V) wire connections before disconnecting.
4. Remove — Disconnect the primary and secondary leads, then unbolt the failed transformer from its bracket.
5. Install — Mount the new transformer and reconnect the 115V primary and 24V secondary leads exactly per your photo.
6. Test — Restore power, confirm 24VAC at the secondary with a meter, and verify the furnace responds to a thermostat call.

Signs You Need a Replacement

• Furnace completely unresponsive with no control-board lights.
• No 24VAC measured at the transformer secondary terminals.
• Repeatedly blown low-voltage fuse on the control board.
• Burnt smell or scorched transformer housing.

Shipping & Returns

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