Tempstar Low Pressure Switch Assembly for T4H418GKD100 | Ships Today

Overview

This OEM low pressure switch assembly (part number 1177594) protects the Tempstar T4H418GKD100 heat pump against loss-of-charge and low-suction conditions. Wired into the 24V control circuit, the switch opens when refrigerant pressure drops below its trip threshold — shutting down the compressor to prevent it from running with insufficient refrigerant. A failed or stuck switch leads to nuisance lockouts, a compressor that won't start, or, if stuck closed, an unprotected compressor at risk of mechanical damage during a low-charge event.

Specifications

Compatibility

Built for the Tempstar T4H418GKD100 and shared ICP / Heil / Comfortmaker heat pump platforms using the same low-pressure protection assembly. Confirm part number 1177594 and the connection fitting type before installing.

Installation Guide

1. Safety First — Disconnect power and verify zero voltage with a multimeter; recover or isolate refrigerant per the switch's connection type.
2. Access — Remove the outdoor unit service panel to reach the switch and its leads.
3. Document — Photograph the wiring and the switch's location on the refrigerant line.
4. Remove — Disconnect the leads and remove the old switch (unthread the Schrader-mount or de-braze per the fitting).
5. Install — Mount the new switch, reconnect the 24V leads per your photo, and leak-check any refrigerant connection.
6. Test — Restore power and verify the compressor starts and the switch holds the circuit closed at normal operating pressure.

Signs You Need a Replacement

• Compressor locks out or won't start with adequate charge
• Intermittent nuisance trips on the low-pressure circuit
• Switch fails a continuity test at normal operating pressure
• Visible corrosion or damage to the switch body or terminals

Shipping & Returns

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