ICP Transformer for WFMR090B042B3 — 40VA 120/24V | Ships Today

Overview

This is a genuine OEM 40VA control transformer (part #1177217) for the ICP / Tempstar / Heil WFMR090B042B3 gas furnace. It steps incoming 120V line voltage down to 24V to power the furnace control board, gas valve, inducer relay, and thermostat circuit. The 40VA rating supplies enough current to drive the full low-voltage control sequence. When the transformer fails — from an open primary winding, a shorted secondary, or a tripped internal fuse link — the entire 24V system loses power, the control board goes dark, and the furnace will not respond to any thermostat call. This OEM unit matches the original primary/secondary voltages and VA capacity for a plug-and-play replacement.

Specifications

Compatibility

Engineered as a direct OEM replacement for the ICP Tempstar Heil WFMR090B042B3 furnace and other ICP-family models using the same 40VA 120/24V control transformer. Verify your existing transformer's VA rating and primary/secondary voltages before installing.

Installation Guide

1. Safety First — Disconnect power at the switch and breaker; verify zero voltage with a multimeter.
2. Access — Remove the furnace control or blower compartment service panel.
3. Document — Photograph all primary and secondary wire connections before disconnecting.
4. Remove — Disconnect the 120V primary and 24V secondary leads, then unbolt the failed transformer from its bracket.
5. Install — Mount the new transformer and reconnect the line and low-voltage leads exactly per your photo.
6. Test — Restore power and verify 24V at the secondary plus a normal startup sequence.

Signs You Need a Replacement

• No 24V power to the control board or thermostat
• Furnace completely unresponsive to a heat call
• Measured 0V on the secondary with 120V present on the primary
• 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.