{"product_id":"four-seasons-20991-a-c-trinary-switch","title":"Four Seasons 20991 A\/C Trinary Switch","description":"\u003ch2\u003eFour Seasons 20991 A\/C Trinary Pressure Switch\u003c\/h2\u003e\u003cp\u003eThe Four Seasons Pressure Switch line includes this system-mounted trinary pressure switch for HVAC A\/C clutch and compressor control. Part number 20991 is a 12-volt, 4-terminal switch with a male connector and male M11 x 1.00 fitting, built in steel and specified with Weather Pack protection.\u003c\/p\u003e\u003cp\u003eCompatible With Lexus RX300, Mitsubishi Galant, and Mitsubishi Mirage applications, this Four Seasons 20991 switch is used in A\/C systems that need pressure-based control for compressor and fan operation. It meets or exceeds OEM requirements and is set up as an open-style trinary pressure switch for system-mounted installation.\u003c\/p\u003e\u003ch2\u003eKey Features\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eFour Seasons Pressure Switch line, part number 20991\u003c\/li\u003e\n\u003cli\u003eTrinary A\/C pressure switch for HVAC compressor and fan control\u003c\/li\u003e\n\u003cli\u003e12-volt electrical design with 4 pin terminals\u003c\/li\u003e\n\u003cli\u003eMale connector and male fitting with M11 x 1.00 thread size\u003c\/li\u003e\n\u003cli\u003eSteel construction with Weather Pack protection\u003c\/li\u003e\n\u003cli\u003eSystem-mounted layout that meets or exceeds OEM specifications\u003c\/li\u003e\n\u003cli\u003ePressure operating points: low on 30 psi, low off 29 psi, medium on 250 psi, medium off 210 psi, high on 350 psi, high off 455 psi\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eDetailed Description\u003c\/h2\u003e\u003cp\u003eThe Four Seasons 20991 trinary pressure switch monitors refrigerant pressure and helps manage A\/C clutch engagement and condenser fan operation through defined low, medium, and high pressure thresholds. This pressure switch is a direct-fit style component for select Lexus RX300, Mitsubishi Galant, and Mitsubishi Mirage vehicles, making it a practical choice when replacing a failed HVAC pressure control switch in the original system-mounted location. The Four Seasons 20991 part number is commonly searched for A\/C clutch and compressor service, especially when diagnosing pressure-related cycling or fan control concerns.\u003c\/p\u003e\u003cp\u003eThis Four Seasons Pressure Switch product line is built for automotive HVAC service where accurate pressure signaling matters. The open\/open configuration, pin terminals, and Weather Pack connection support clean integration into the vehicle’s A\/C electrical circuit.\u003c\/p\u003e\u003ch2\u003eCommon Problems This Part Can Address\u003c\/h2\u003e\u003cul\u003e\n\u003cli\u003eA\/C compressor not engaging due to pressure switch failure\u003c\/li\u003e\n\u003cli\u003eCondenser fan control issues tied to refrigerant pressure sensing\u003c\/li\u003e\n\u003cli\u003eIntermittent A\/C cycling caused by worn switch contacts\u003c\/li\u003e\n\u003cli\u003eHVAC system shutdown from incorrect high- or low-pressure readings\u003c\/li\u003e\n\u003cli\u003eFault codes or drivability complaints related to A\/C pressure control\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch2\u003eInstallation Notes and Tips\u003c\/h2\u003e\u003cp\u003eVerify the original switch connector style, terminal count, and M11 x 1.00 thread before installation. Because this is a system-mounted trinary pressure switch, confirm refrigerant pressure is properly recovered and the A\/C circuit is inspected for leaks or wiring damage before replacing the part. For fitment, this part fits 1999-2003 Lexus RX300, 1994-1998 Mitsubishi Galant, and 1991-1992 Mitsubishi Mirage.\u003c\/p\u003e\u003ch2\u003eQuality Assurance\u003c\/h2\u003e\u003cp\u003eFour Seasons 20991 meets or exceeds OEM requirements and is built to the specified electrical and mechanical dimensions for the listed applications. This part cross-references Continental 50029 for the same application.\u003c\/p\u003e","brand":"Four Seasons","offers":[{"title":"Default Title","offer_id":44592414982325,"sku":"BBRN-20991","price":52.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0628\/1442\/1173\/files\/FS_20991_Fro.jpg?v=1775067615","url":"https:\/\/www.partcatalog.com\/products\/four-seasons-20991-a-c-trinary-switch","provider":"PartCatalog","version":"1.0","type":"link"}