Tempstar Control Transformer for T9UHX080J12A2 — 40VA 115V to 24V | Ships Today
OEM Guaranteed
Same-Day Ship
30-Day Returns
Secure Checkout
Overview
This is the OEM low-voltage control transformer (OEM part 1172810) for the Tempstar T9UHX080J12A2 gas furnace. The transformer steps down 115V line voltage to the 24V control voltage that powers the thermostat, control board, gas valve, igniter circuit, and relays. Rated at 40VA, it supplies enough current to run the entire low-voltage control circuit. When a transformer fails, the furnace goes completely dead — no thermostat display, no blower, no ignition — even though line power is present. Symptoms include a blown low-voltage fuse, a buzzing or scorched transformer, or an open primary/secondary winding when checked with a multimeter.
Specifications
| Spec | Value |
|---|---|
| Part Number | 1172810 |
| Type | Control Transformer |
| Brand | Tempstar |
| Rating | 40 VA |
| Primary Voltage | 115V |
| Secondary Voltage | 24V |
| Fit | OEM |
Compatibility
Designed as a direct-fit replacement for the Tempstar T9UHX080J12A2 furnace and compatible ICP/Heil/Comfortmaker variants that use the 1172810 transformer. Always match the VA rating and primary/secondary voltages to your original unit before installing.
Installation Guide
- Safety First — Disconnect power at the furnace switch and breaker, then verify zero voltage at the transformer leads with a multimeter.
- Access — Remove the furnace blower/control compartment service panel.
- Document — Photograph all primary and secondary wire connections before disconnecting anything.
- Remove — Disconnect the 115V primary leads and the 24V secondary leads, then unbolt the transformer from its mounting bracket.
- Install — Mount the new transformer, then reconnect the primary and secondary wiring exactly per your photo.
- Test — Restore power and confirm 24V on the secondary and normal thermostat operation.
Signs You Need a Replacement
- Furnace is completely unresponsive with no 24V control power present.
- Repeatedly blown low-voltage control fuse.
- Transformer is hot, buzzing, or has a burnt smell.
- Multimeter shows an open or shorted primary/secondary winding.
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