OEM Carrier High & Low Pressure Switch Kit — 312926-252 & 312926-258 for PH13NB042000AAAA

These two OEM pressure switches are the factory-specified replacements for the Carrier PH13NB042000AAAA heat pump. The high pressure switch (312926-252, 670/470 PSI) monitors refrigerant discharge pressure and opens the safety circuit if pressure exceeds safe operating limits, protecting the compressor from damage due to overcharge, blocked condenser airflow, or a failed condenser fan motor. The low pressure switch (312926-258, 55/23 PSI) monitors suction-side pressure and opens the circuit under low-charge or freeze conditions, preventing the compressor from running in a damaging vacuum. When either switch fails, symptoms typically include nuisance lockouts, fault codes indicating high or low pressure trips, or a system that short-cycles and shuts down within seconds of startup.

• Part Numbers & Specs: 312926-252 High Pressure Switch — 670 PSI cut-out / 470 PSI cut-in | 312926-258 Low Pressure Switch — 55 PSI cut-out / 23 PSI cut-in | Both are Carrier Factory Authorized Parts (FAP) meeting OEM tolerances
• OEM vs Generic: OEM pressure switches are factory-calibrated to exact cut-in/cut-out setpoints. Aftermarket substitutes often carry wider pressure tolerances, which can allow unsafe operating conditions or cause repeated nuisance trips — risking compressor burnout over time.
• Install Difficulty: 3/5 — Refrigerant circuit work requires an EPA 608 certified technician. Tools needed: manifold gauge set, multimeter, wire stripper, and 1/4" flare fittings. Always recover refrigerant before replacing a pressure switch inline with the refrigerant circuit. Confirm electrical connections match the original wiring diagram inside the unit access panel.
• Warranty: 1-year OEM manufacturer warranty. Both units ship same business day from our warehouse, individually packaged and ready to install.

Compatibility: Engineered as direct OEM replacements for Carrier model PH13NB042000AAAA heat pump systems. Verify refrigerant type and system operating pressures against your unit's data plate before ordering. Unsure about fitment? Our HVAC parts specialists confirm compatibility before you buy — order today and get same-day shipping.