OEM Payne High & Low Pressure Switch for Model PA12NA030000AHAA

These OEM pressure switches — HK02ZA395 (High Pressure Switch) and HK02ZB028 (Low Pressure Switch) — are the factory-specified replacements for the Payne PA12NA030000AHAA heat pump system. Pressure switches monitor refrigerant-side pressure levels to protect the compressor from operating under unsafe high or low pressure conditions. When either switch fails or trips, the system will lock out before completing a heating or cooling cycle, often with no obvious mechanical noise — just a system that refuses to run.

• Specs: HK02ZA395 — High Pressure Switch (opens on excess pressure to protect compressor) | HK02ZB028 — Low Pressure Switch (opens on low refrigerant pressure, indicating possible leak or blockage) | Factory-calibrated setpoints matched to PA12NA030000AHAA refrigerant circuit design | SPST normally closed configuration
• OEM vs Generic: OEM pressure switches are calibrated to exact factory trip and reset pressures. Aftermarket substitutes often carry wider tolerances that can cause nuisance lockouts or — more critically — fail to protect the compressor during a genuine fault condition, leading to costly compressor failure.
• Install difficulty: 3/5 — Refrigerant system work requires an EPA 608 certification. Tools needed: manifold gauge set, wire connectors, flathead screwdriver, and multimeter to verify switch continuity before re-energizing. Always recover refrigerant per EPA regulations before removing either switch from the low or high-side port.
• Warranty: 1-year OEM factory warranty on both HK02ZA395 and HK02ZB028. Orders ship same business day from our warehouse.

Compatibility: Both switches are designed and factory-matched for the Payne PA12NA030000AHAA heat pump. Confirm the faulty switch (high or low side) with your manifold gauge readings before ordering — both part numbers are available individually or as a set. If you are unsure which switch has failed, our technical team can help verify fitment and diagnosis before you order. In stock and ships today.