Tempstar PTAC Thermostat for THA12K25STA — OEM 1058517 | Ships Today

Overview

This is a genuine OEM PTAC thermostat (Tempstar part number 1058517, TSTAT PTAC X) for the Tempstar/Heil THA12K25STA packaged terminal air conditioner. The thermostat is the command center of the PTAC unit: it reads room temperature, compares it to the setpoint, and switches the compressor, fan, and heating element on and off to maintain comfort. When this control fails, the unit may run continuously, fail to start, ignore temperature changes, or display erratic readings. Installing the correct OEM thermostat restores accurate temperature control and proper cycling.

Specifications

Compatibility

Designed as a direct-fit OEM replacement for the Tempstar/Heil THA12K25STA PTAC unit. This thermostat control is shared across the THA-series PTAC platform built by ICP (International Comfort Products) and sold under the Tempstar, Heil, and Comfortmaker brands. Verify the part number 1058517 on your existing control before ordering.

Installation Guide

1. Safety First — Disconnect power to the PTAC unit at the receptacle or breaker and verify zero voltage with a multimeter.
2. Access — Remove the front grille and decorative panel to expose the control housing.
3. Document — Photograph all wiring connections and harness positions before disconnecting anything.
4. Remove — Unplug the wiring connectors from the old thermostat control and release its mounting clips/screws.
5. Install — Seat the new OEM thermostat, secure the mounts, and reconnect each connector exactly per your photo.
6. Test — Restore power, set a cooling and heating call, and confirm the unit cycles and holds the setpoint.

Signs You Need a Replacement

• Unit runs constantly or won't shut off at setpoint
• PTAC fails to start in cool or heat mode
• Erratic, frozen, or blank temperature display
• Room temperature never matches the selected setting

Shipping & Returns

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