ICP 40VA Transformer for WFML090C048B1 — 120/24V Control Transformer | Ships Today

Overview

This OEM 40VA control transformer steps 120V line voltage down to 24V to power the low-voltage control circuit on your ICP / Heil / Tempstar WFML090C048B1 furnace. The 24V output feeds the thermostat, gas valve, control board relays, and inducer/blower controls. When a transformer fails — often from a shorted control wire, a stuck contactor, or simple age — the entire 24V circuit goes dead: the thermostat screen goes blank (if R-powered) and the furnace will not respond to a call for heat. This is the correct OEM part 1177217, rated 40VA with a 120V primary and 24V secondary.

Specifications

Compatibility

Direct OEM replacement for the ICP/Heil/Tempstar/Comfortmaker WFML090C048B1 furnace. Confirm your existing transformer is a 120V-primary, 40VA unit before ordering — some installations use 208/240V multi-tap transformers.

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/electrical service panel.
3. Document — Photograph all primary (line) and secondary (24V) leads before disconnecting.
4. Remove — Disconnect the primary and secondary wires, then unbolt the transformer from its mounting bracket.
5. Install — Mount the new transformer, connect the 120V primary leads to line, and wire the 24V secondary to R and C per your photo.
6. Test — Restore power, measure 24V across the secondary terminals, and run a heat cycle to confirm operation.

Signs You Need a Replacement

• No 24V power — thermostat blank and furnace unresponsive.
• Blown low-voltage fuse on the control board that re-blows on reset.
• Burnt smell or visibly scorched transformer windings.
• No measurable 24V at the secondary with 120V present on the primary.

Shipping & Returns

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