Four Seasons 20978 HVAC Binary Switch

Four Seasons 20978 Pressure Switch Overview

The Four Seasons 20978 pressure switch is a system-mounted HVAC binary switch built for pressure-based compressor control. It uses a rectangular female connector, a 2-terminal layout, and a 3/8 in. x 24 female fitting thread size for a direct service replacement in the air conditioning system.

Compatible With 1985-1990 Nissan Pulsar NX and 1986-1989 Nissan Sentra applications, this Four Seasons Pressure Switch line part is built to meet or exceed OEM requirements. The 20978 is a practical choice when you need a pressure switch replacement for Nissan Pulsar NX or Nissan Sentra HVAC service.

Key Features

• Four Seasons Pressure Switch, part number 20978
• Binary HVAC switch with open/closed operation
• System-mounted design for pressure control in the A/C circuit
• Rectangular female connector with 2 terminals
• White steel construction
• Female fitting with 3/8 in. x 24 thread size
• Operate pressure: 35 psi on, 32 psi off
• Meets or exceeds OEM specifications

Detailed Description

The Four Seasons 20978 HVAC binary switch monitors system pressure and signals the compressor circuit based on preset low-pressure thresholds. Its open/closed binary style supports pressure-based cycling in the air conditioning system, while the system-mounted configuration and female threaded fitting simplify replacement on supported Nissan platforms. If you are sourcing a Four Seasons 20978 pressure switch for Nissan Sentra or Nissan Pulsar NX service, this part matches the listed fitment and connector style.

This part cross-references Monroe Shocks & Struts (e.g., 172286, 182286) for the same application.

What It Helps Address

• Compressor cycling caused by incorrect pressure switch operation
• A/C system shutdown related to low-pressure cutoff behavior
• Intermittent compressor engagement from worn switch contacts
• Faults tied to damaged connector or threaded switch interfaces
• HVAC pressure control issues on listed Nissan applications

Installation Notes and Tips

Verify the connector shape, terminal count, and 3/8 in. x 24 female thread size before installation. Confirm the system-mounted location and compare the existing switch’s pressure settings to the replacement part. Use proper HVAC service procedures when removing or installing the switch to avoid refrigerant loss and system contamination.

Quality Assurance

Four Seasons states that this pressure switch meets or exceeds OEM requirements, making the 20978 a specification-based replacement for supported Nissan HVAC systems.