Tempstar 40VA Transformer for TEB12K25RTA — 208/240V to 24V with Relays | Ships Today
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Overview
This is the genuine OEM 40VA control transformer (OEM 1056899) for the Tempstar TEB12K25RTA PTAC, supplied with its companion 24V control relays (OEM 1053004, single relay; OEM 1060940, 24V DPST relay). The transformer steps the line-voltage 208/240V supply down to the 24V control voltage that powers the thermostat, relays, and switching circuit. When a control transformer fails — often from a shorted secondary or an overloaded class-2 circuit — the entire low-voltage control system goes dead: no cooling, no heating, and an unresponsive thermostat even though line power is present. The included relays handle the actual switching of the heating and cooling loads on the 24V side.
Specifications
| Spec | Value |
|---|---|
| OEM Part Numbers | 1056899 (Transformer), 1053004 (Relay), 1060940 (DPST Relay) |
| Type | Step-Down Control Transformer + Relays |
| Brand | Tempstar / ICP / Heil |
| Rating | 40 VA |
| Primary Voltage | 208/240V |
| Secondary Voltage | 24V |
| Fits Model | TEB12K25RTA |
Compatibility
A direct-fit replacement for the Tempstar TEB12K25RTA PTAC. These components are shared across the ICP/Tempstar/Heil TEB12K25 packaged terminal unit family — verify your unit's model and serial tag and confirm primary voltage (208/240V) before ordering.
Installation Guide
- Safety First — Disconnect power at the unit disconnect and verify zero voltage with a multimeter.
- Access — Remove the PTAC front cover and control box panel.
- Document — Photograph the transformer and relay wiring before disconnecting.
- Remove — Disconnect the primary and secondary leads, unbolt the old transformer/relays from the control plate.
- Install — Mount the new transformer and relays, reconnect every lead per your photo, and confirm primary taps match line voltage.
- Test — Restore power and verify 24V at the secondary and proper relay switching on a call for heat/cool.
Signs You Need a Replacement
- No 24V at the secondary — entire control circuit is dead
- Unit has line power but thermostat is unresponsive
- Blown low-voltage fuse or repeated control-circuit faults
- Relays 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.
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