ICP 40VA Transformer 120-24V for WFMR045A036B2 — Furnace Control Transformer (1177217) | Ships Today

Overview

This is the genuine OEM 40VA control transformer for the ICP/Tempstar/Heil WFMR045A036B2 gas furnace, OEM part number 1177217. The transformer steps the 120V line voltage down to the 24V low-voltage power that runs the thermostat, control board, gas valve, and relays. Rated at 40 VA, it supplies enough current for the full control circuit including a connected air conditioner contactor. When a transformer fails — usually from a shorted thermostat wire, a stuck contactor, or simple age — the furnace goes completely dead with no display, no thermostat power, and no response to a heat or cool call. A blown transformer often takes its inline fuse with it, so inspect the control wiring before installing a replacement.

Specifications

Compatibility

Direct-fit replacement for the ICP family WFMR045A036B2 furnace and shared platforms sold under the Tempstar, Heil, and Comfortmaker brands. Verify the 120V primary, 24V secondary, and 40 VA rating against your existing transformer before installing.

Installation Guide

1. Safety First — Disconnect power at the furnace switch and breaker and verify zero voltage with a multimeter.
2. Access — Remove the furnace control-compartment service panel.
3. Document — Photograph the primary (120V) and secondary (24V) leads before disconnecting.
4. Remove — Disconnect the four leads, remove the transformer mounting screws, and lift it out.
5. Install — Mount the new transformer and reconnect the primary and secondary leads exactly per your photo.
6. Test — Restore power, confirm 24V across the secondary, and verify the thermostat and control board power up.

Signs You Need a Replacement

• Furnace is completely dead with no thermostat or control board power.
• No measurable 24V on the secondary terminals.
• Transformer is hot, buzzing loudly, or smells burnt.
• Control fuse blows repeatedly after a wiring short.

Shipping & Returns

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