OEM Payne High & Low Pressure Switch for Model PA12NA03600GACAA

These OEM pressure switches — HK02ZA395 (High Pressure Switch) and HK02ZB028 (Low Pressure Switch) — are the factory-specified replacements for the Payne PA12NA03600GACAA split-system heat pump. Pressure switches monitor refrigerant circuit pressures on both the high and low sides, protecting the compressor from operating outside safe pressure limits. When either switch fails or trips, the system will lock out on a fault code before completing a heating or cooling cycle, leaving you with no conditioned air and a blinking status LED on the control board.

• Specs: HK02ZA395 — High-Side Pressure Switch, factory-calibrated cut-out setpoint | HK02ZB028 — Low-Side Pressure Switch, factory-calibrated cut-in setpoint | 1/4" SAE flare refrigerant port | 24V control circuit signal | Matched to R-410A operating pressures for the PA12NA03600GACAA
• OEM vs Generic: OEM pressure switches are calibrated to exact factory setpoints for R-410A refrigerant pressures. Generic aftermarket switches frequently carry wider pressure tolerances, risking nuisance trips or — more critically — failing to protect the compressor during a true high-pressure event, potentially leading to catastrophic compressor failure.
• Install Difficulty: 3/5 — Refrigerant circuit work requires EPA 608 certification. Tools needed: manifold gauge set, refrigerant recovery equipment, 1/4" SAE wrench, multimeter for continuity verification, and safety glasses. Always recover refrigerant before disconnecting the switch. Photograph wiring harness connections prior to removal.
• Warranty: 1-year OEM factory warranty on both HK02ZA395 and HK02ZB028. Orders placed before cutoff ship same business day from our climate-controlled warehouse.

Compatibility: These switches are designed specifically for the Payne PA12NA03600GACAA 3-ton split-system heat pump. Confirm OEM part numbers HK02ZA395 and HK02ZB028 against your unit's wiring diagram or data plate before ordering. If you are unsure whether your system requires the high-side, low-side, or both switches, our HVAC parts specialists can verify fitment before you purchase — call or chat us today. In stock and ready to ship.