OEM Carrier High & Low Pressure Switch Kit — 312926-252 & 312926-258 for Model PH13NB018000AAAA

These two OEM Carrier pressure switches are the factory-specified refrigerant circuit protection controls for the Carrier PH13NB018000AAAA heat pump. The high pressure switch (312926-252, 670/470 PSI) monitors the high-side refrigerant circuit and opens the compressor circuit if pressure exceeds the 670 PSI cutout threshold, protecting against refrigerant overcharge, blocked condenser airflow, or failed condenser fan motor. The low pressure switch (312926-258, 55/23 PSI) monitors the low-side and opens the circuit when pressure drops below 23 PSI, guarding against refrigerant undercharge, a restricted metering device, or evaporator freeze-up. When either switch fails or trips without resetting, the system will enter a fault lockout — the unit won't cool or heat, and fault codes pointing to high- or low-pressure trips are common symptoms.

• Part Numbers & Specs: 312926-252 High Pressure Switch — 670 PSI cutout / 470 PSI reset | 312926-258 Low Pressure Switch — 55 PSI cutout / 23 PSI reset | Both are genuine Carrier Factory Authorized Parts (FAP)
• OEM vs Generic: OEM switches use factory-calibrated setpoints with tight pressure tolerances. Generic aftermarket switches frequently drift off setpoint, causing nuisance trips or — worse — failing to open during a real over-pressure event, risking compressor damage.
• Install Difficulty: 3/5 — Refrigerant circuit work requires an EPA 608 certification. Tools needed: manifold gauge set, multimeter, refrigerant recovery unit, 1/4" flare fittings, wire strippers. Always recover refrigerant before replacing a pressure switch on the high-side port. Low-side switch replacement follows the same procedure.
• Warranty: 1-year OEM manufacturer warranty on both switches. Orders placed by 3 PM local time ship same business day from our warehouse.

Compatibility: Engineered as direct OEM replacements for the Carrier PH13NB018000AAAA heat pump. Verify refrigerant type (R-410A) and confirm pressure switch port locations on your unit's wiring diagram before ordering. Not sure if these are your exact switches? Our HVAC parts specialists will confirm fitment before you buy — call or chat now.