Tempstar 40VA Transformer for TEB09K34RTA — 208/240V to 24V | Ships Today

Overview

This genuine OEM control transformer, part 1056899, steps the Tempstar TEB09K34RTA's 208/240V line voltage down to the 24V needed to power the thermostat, relays, and contactor coil. Rated at 40VA, it supplies the full low-voltage control circuit. This listing also covers the unit's 24V control relays — part 1053004 (relay 24V) and part 1060940 (relay 24V DPST) — which switch the loads the transformer energizes. A failed transformer leaves the entire unit dead with no 24V control power, while a failed relay prevents specific functions from starting even when the transformer is healthy.

Specifications

Compatibility

Factory-correct transformer and relay group for the Tempstar TEB09K34RTA. Confirm the part numbers and 208/240V primary against your unit rating plate before ordering to guarantee fitment.

Installation Guide

1. Safety First — Disconnect power at the breaker and confirm zero voltage with a multimeter before servicing.
2. Access — Remove the service panel to reach the control box and transformer.
3. Document — Photograph all primary (line) and secondary (24V) wire connections before disconnecting.
4. Remove — Unbolt the old transformer and any failed relay, then disconnect the leads, noting terminal positions.
5. Install — Mount the new transformer and relay, reconnecting primary to line and secondary to the 24V control circuit per your photo.
6. Test — Restore power and verify 24V across the transformer secondary, then confirm the unit energizes on a call.

Signs You Need a Replacement

• No 24V at the secondary — unit completely unresponsive
• Repeatedly blown low-voltage fuse or tripped control circuit
• Transformer is hot, buzzing, or shows burn marks
• Relay fails to click or its contacts are pitted or welded

Shipping & Returns

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