Tempstar Low Pressure Switch Assembly for T4H448GKD100 — OEM #1177594 | Ships Today

Overview

This OEM low pressure switch assembly (part #1177594) is a refrigerant-side safety control on your Tempstar T4H448GKD100. It opens the 24V control circuit when suction pressure drops too low — protecting the compressor from running on a low charge, a blocked metering device, or a frozen coil. When the switch fails or the system loses charge, you'll see the unit short-cycle, lock out on a low-pressure fault, or refuse to start the compressor at all. A switch that's stuck open prevents any cooling/heating call from energizing the compressor.

Specifications

Compatibility

Direct OEM fit for the Tempstar T4H448GKD100 and other ICP-family (Heil, Comfortmaker, Tempstar) units originally equipped with low pressure switch #1177594. Confirm the connection fitting and cut-in/cut-out pressures against your existing switch.

Installation Guide

1. Safety First — Disconnect power and verify zero voltage with a multimeter; relieve any system pressure per EPA procedure if the fitting is open to refrigerant.
2. Access — Remove the service panel to reach the switch and its line connection.
3. Document — Photograph the two control wires and the switch mounting/fitting.
4. Remove — Disconnect the 24V leads and unthread the switch from the Schrader/port fitting (most are self-sealing).
5. Install — Thread on the new switch, snug the fitting, and reconnect the control leads per your photo.
6. Test — Restore power and confirm the compressor energizes and the unit holds without a low-pressure lockout.

Signs You Need a Replacement

• Compressor won't start / unit locks out on low pressure
• System short-cycles repeatedly
• Switch reads open with normal charge and pressures
• Corroded or damaged switch body or terminals

Shipping & Returns

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