ICP 24V Transformer for ZAMA004AHB3 — SPST 40VA Control | Ships Today

Overview

This OEM 24V control transformer (ICP part #1057251) delivers the low-voltage power that operates the thermostat, relays, and control circuits in your air handler or furnace. Rated at 40VA, it steps line voltage down to 24V for the SPST control loop. When it fails, the whole 24V circuit goes dead — the thermostat blanks, relays and contactors will not energize, and the equipment will not run. Common causes include a shorted secondary winding, an overloaded control circuit, or surge-induced overheating that opens the windings.

Specifications

Compatibility

Direct-fit replacement for ICP, Tempstar, Heil, and Comfortmaker equipment using the 1057251 control transformer, including model ZAMA004AHB3. Confirm the primary voltage and VA rating against the original part before installing.

Installation Guide

1. Safety First — Disconnect power and verify zero voltage with a multimeter.
2. Access — Remove the control-box/service panel to reach the transformer.
3. Document — Photograph primary and secondary wiring before disconnecting.
4. Remove — Disconnect the leads, unbolt the transformer from its bracket, and remove it.
5. Install — Mount the new transformer and reconnect primary and secondary leads per your photo.
6. Test — Restore power and verify 24V across the secondary and normal operation.

Signs You Need a Replacement

• Blank thermostat or no 24V at the control board
• Relays and contactors will not energize
• Repeatedly blown low-voltage fuse
• Transformer is hot, buzzing, or visibly burned

Shipping & Returns

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