Four Seasons 20949 A/C Trinary Switch

Four Seasons 20949 Trinary Pressure Switch

The Four Seasons Pressure Switch 20949 is a system-mounted A/C trinary switch built for 12-volt HVAC systems. It uses a 4-terminal oval male connector with Weather Pack sealing and a steel body for direct pressure control in the air conditioning circuit.

Key Features

• System-mounted trinary pressure switch for A/C clutch and compressor control
• 12-volt electrical design with pin terminals
• Oval male connector with Weather Pack protection
• 3/8" x 24 fitting thread size
• Steel construction
• Meets or exceeds OEM requirements
• Low-pressure operation: 33 psi on, 35 psi off
• Medium-pressure operation: 175 psi on
• Fan control: closed
• Compressor control: open

Detailed Description

Four Seasons 20949 is a trinary pressure switch used in automotive A/C systems to monitor refrigerant pressure and manage compressor and fan operation. As a system-mounted pressure switch, it supports stable HVAC performance by responding to low and medium pressure thresholds in the circuit. This Four Seasons Pressure Switch line is built for OE-style service replacement, and part number 20949 is listed as meeting or exceeding OEM requirements. This part cross-references Monroe Shocks & Struts (e.g., 172286, 182286) for the same application.

Compatible With 1990 Lexus LS400 and 1991 Lexus LS400, as well as 1989-1990 Toyota Celica and 1991 Toyota Celica built to 10/1990 or 12/1990 depending on application notes. If you are searching for a Lexus LS400 A/C trinary switch or a Toyota Celica pressure switch replacement, Four Seasons 20949 is the direct part number to reference.

What It Helps Address

• A/C compressor cycling caused by incorrect pressure switch operation
• Condenser fan control issues tied to system pressure
• Low refrigerant pressure shutdown events
• High-pressure A/C protection logic in the HVAC circuit
• Electrical connection problems at the pressure switch interface

Installation Notes and Tips

Verify the connector shape, terminal count, and fitting thread size before installation. Confirm the vehicle build date and application notes for Lexus LS400 and Toyota Celica fitment, since the listed coverage includes date-specific exceptions. Inspect the A/C system for refrigerant charge, wiring condition, and connector sealing before replacing the switch.

Quality Assurance

Four Seasons 20949 is engineered to meet or exceed OEM specifications for pressure-switch function and fitment. The steel housing and Weather Pack connector support dependable service in automotive HVAC environments.