ICP 40VA Transformer for SUP23M2401AIA — 120V to 24V with 24VAC Relay | Ships Today

Overview

This OEM control package for the ICP / Heil / Tempstar SUP23M2401AIA includes the 40VA step-down control transformer (part L01F009, 120V primary to 24V secondary) and its companion 24VAC relay (part L01H009). The transformer is the heart of the low-voltage control circuit: it converts line voltage into the 24-volt power that runs the thermostat, relays, and safety controls. When a transformer fails — usually from a shorted secondary, an overloaded VA rating, or age — the system goes completely dead at the thermostat even though line power is present. The included 24VAC relay switches loads such as the blower or contactor on command from the control circuit. A burned-out transformer or chattering relay is a common cause of no-heat and no-cool failures.

Specifications

Compatibility

Direct OEM fit for the ICP / Heil / Tempstar SUP23M2401AIA control circuit. The 40VA 120-to-24V transformer and 24VAC relay are widely shared across ICP-family equipment, so these parts also service many comparable Heil, Tempstar, and Comfortmaker units. Confirm your existing transformer primary is 120V and rated 40VA before installing.

Installation Guide

1. Safety First — Disconnect power at the breaker and verify zero voltage at the transformer leads with a multimeter.
2. Access — Remove the control-panel cover to reach the transformer and relay.
3. Document — Photograph every primary and secondary wire and the relay terminals before disconnecting.
4. Remove — Disconnect the leads, unbolt the old transformer and relay, and remove them from the panel.
5. Install — Mount the new transformer and relay, then reconnect 120V primary, 24V secondary, and relay wiring exactly per your photo.
6. Test — Restore power, confirm 24VAC at the secondary with a meter, and verify the thermostat and relay-driven loads energize correctly.

Signs You Need a Replacement

• System completely dead at the thermostat with line power present
• No 24VAC reading at the transformer secondary
• Burnt smell, melted housing, or tripped internal fuse on the transformer
• Relay buzzing, chattering, or failing to pull in

Shipping & Returns

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