Tempstar 40VA Transformer for THB07K34RTA — 208/240V to 24V | Ships Today

Overview

This OEM 40VA control transformer (OEM 1056899) steps line voltage of 208/240V down to the 24V Class 2 control circuit used throughout the Tempstar THB07K34RTA PTAC unit. The listing also covers the unit's 24V control relays — a single-throw relay (OEM 1053004) and a DPST relay (OEM 1060940) — that switch the compressor and fan loads. When a control transformer fails, the entire 24V circuit goes dead: the thermostat is unresponsive, relays won't pull in, and nothing energizes even though line voltage is present. A buzzing, blackened, or open-winding transformer is a clear replacement candidate.

Specifications

Compatibility

Direct OEM replacement for the Tempstar / ICP / Heil THB07K34RTA PTAC control circuit. The 40VA transformer and matching 24V relays are the original control components for this model.

Installation Guide

1. Safety First — Disconnect power at the breaker and verify zero voltage with a multimeter on both primary and secondary leads.
2. Access — Remove the PTAC cabinet cover to reach the control panel and transformer bracket.
3. Document — Photograph the primary and secondary wiring before disconnecting.
4. Remove — Unscrew the transformer from its bracket and disconnect the 208/240V primary and 24V secondary leads.
5. Install — Mount the new transformer, reconnect primary and secondary per your photo, and confirm relay wiring.
6. Test — Restore power and verify 24V at the secondary and that the relays energize.

Signs You Need a Replacement

• No 24V control power; thermostat and relays completely dead.
• Audible buzzing or humming from the transformer.
• Scorched, discolored, or melted transformer housing.
• Open or shorted winding read on a multimeter.

Shipping & Returns

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