ICP 40VA Transformer for WFML090B042B1 — 120V to 24V Furnace Control | Ships Today
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Overview
This OEM 40VA control transformer (part 1177217) steps 120V line voltage down to 24V to power the low-voltage control circuit of the ICP / Tempstar / Heil WFML090B042B1 gas furnace. The transformer is what energizes the thermostat, control board, gas valve, and relays — without a healthy 24V output, nothing in the control system responds. Rated at 40VA with a 120V primary and 24V secondary, it supplies enough capacity for the furnace controls plus a connected cooling contactor or accessory. When a transformer fails — often from a short downstream, a stuck contactor, or simple age — the furnace goes completely dead: no thermostat display, no inducer, no ignition. Symptoms include a blank or unpowered thermostat, a furnace that won't respond to any call, a blown low-voltage fuse on the control board, or a burnt smell near the transformer.
Specifications
| Spec | Value |
|---|---|
| Part Number | 1177217 |
| Type | Step-Down Control Transformer |
| Rating | 40 VA |
| Primary Voltage | 120V |
| Secondary Voltage | 24V |
| Brand | ICP / Tempstar / Heil |
| Fitment | OEM Direct Replacement |
Compatibility
Direct OEM fit for the ICP / Tempstar / Heil WFML090B042B1 gas furnace. The 40VA 120V-to-24V rating is shared across many ICP-built WFML-series furnaces sold under the Tempstar, Heil, and Comfortmaker brands. Confirm your model and the transformer's VA and voltage ratings before ordering.
Installation Guide
- Safety First — Disconnect power at the furnace switch and breaker, and verify zero voltage with a multimeter.
- Access — Remove the furnace electrical access panel.
- Document — Photograph all primary (120V) and secondary (24V) wire connections before disconnecting.
- Remove — Disconnect the wiring, unbolt the transformer from its mounting tab, and lift it out.
- Install — Mount the new transformer, then reconnect the 120V primary and 24V secondary leads exactly per your photo.
- Test — Restore power, confirm 24V at the secondary with a meter, and verify the thermostat and furnace respond normally.
Signs You Need a Replacement
- Thermostat is blank or completely unpowered.
- Furnace is dead and does not respond to any call for heat.
- Repeatedly blown low-voltage fuse on the control board.
- Burnt smell or visible scorching at the transformer.
Shipping & Returns
Ships same day before 3 PM CST. 30-day returns. Backed by the National HVAC Parts fitment guarantee.
Shipping Information
- Orders placed before 3PM CST ship same business day
- Standard delivery: 2-5 business days
- Express shipping available at checkout
- Free shipping on orders over $75
- Tracking number emailed upon shipment
Return Policy
- 30-day returns on unused parts in original packaging
- Electrical parts (capacitors, contactors, control boards) are final sale once installed
- Email info@nationalhvacparts.com to initiate a return
- Refunds processed within 5-7 business days