ICP 40VA Transformer for WFMR135D066B3 — 120V to 24V OEM 1177217 | Ships Today

Overview

This OEM control transformer (part 1177217) supplies the 24V control circuit on the ICP / Tempstar / Heil WFMR135D066B3 furnace. It steps the incoming 120V line voltage down to 24V at 40VA, powering the thermostat, gas valve, control board relays, and safety circuits. When a transformer fails — usually from a shorted thermostat wire, a stuck contactor, or simple age — the entire low-voltage system goes dead: no thermostat display, no call for heat or cool, and no response from the equipment. A blown internal fuse link or burnt windings is a common no-power diagnosis. Installing the correct 40VA OEM transformer restores stable control voltage to the whole system.

Specifications

Compatibility

Direct-fit replacement for the ICP-family WFMR135D066B3 furnace and the shared Tempstar, Heil, and Comfortmaker units that use a 40VA 120-to-24V control transformer. Verify your primary voltage is 120V before installing.

Installation Guide

1. Safety First — Disconnect power at the furnace switch and breaker. Verify zero voltage with a multimeter on both primary and secondary leads.
2. Access — Remove the furnace service/control panel.
3. Document — Photograph every primary and secondary wire and its terminal before disconnecting.
4. Remove — Disconnect the leads, unscrew the transformer from the mounting bracket or control panel, and lift it out.
5. Install — Mount the new transformer, reconnect the 120V primary and 24V secondary leads exactly per your photo, and ensure terminals are tight.
6. Test — Restore power and confirm 24V across the secondary, a live thermostat, and a normal heat call.

Signs You Need a Replacement

• Thermostat is blank and the system is completely unresponsive.
• No 24V measured across the secondary terminals.
• Transformer is hot, humming loudly, or smells burnt.
• Repeated control-fuse failures pointing to a shorted or failing transformer.

Shipping & Returns

Ships same day on orders placed before 3 PM CST. 30-day hassle-free returns. Backed by the National HVAC Parts fitment guarantee.