Standard Ignition RY-4 HVAC Automatic Temperature Control (ATC) Relay

HVAC Relay for Cadillac ATC Systems

The Standard Ignition RY-4 is an HVAC automatic temperature control relay built for Cadillac climate control systems that use a blower motor relay with a bracketed mount. It is a 12-volt, 4-terminal relay with a rectangular connector and male blade terminals for direct replacement service.

Fits 1969-1975 Cadillac Commercial Chassis, N/A; Fits 1969-1975 Cadillac DeVille, N/A; Fits 1969-1975 Cadillac Fleetwood, N/A; Fits 1971-1975 Cadillac Eldorado, N/A; Fits 1976 Cadillac Commercial Chassis, N/A; Fits 1976 Cadillac DeVille, N/A; Fits 1976 Cadillac Fleetwood, N/A; Fits 1976-1978 Cadillac Eldorado, N/A; Fits 1976-1978 Cadillac Seville, N/A; Fits 1977-1979 Cadillac Eldorado, N/A; Fits 1976-1979 Cadillac Seville, N/A.

• Blower motor relay function for HVAC automatic temperature control systems
• 25-amp amperage rating for electrical load handling
• Rectangular connector shape with 4 male blade terminals
• Mounting bracket included for bracketed installations
• 12-volt relay construction for automotive HVAC circuits

Detailed Product Overview

Standard Ignition RY-4 is an HVAC Automatic Temperature Control (ATC) relay used in Cadillac climate control circuits where the blower motor is controlled through the ATC system. It is listed for Cadillac Eldorado, Seville, DeVille, Fleetwood, and Commercial Chassis applications across the 1969-1979 model years shown in the fitment data. This part cross-references FEL-PRO 35769 and Gates 19873 for the same application.

Common Symptoms This Relay May Address

• Blower motor not responding to ATC commands
• Intermittent HVAC fan operation
• Loss of automatic temperature control blower function
• Electrical relay failure in the climate control circuit
• Improper blower motor switching in Cadillac HVAC systems

Installation Notes

Verify the vehicle uses automatic temperature control before installation, especially on listed Cadillac Eldorado and DeVille applications where ATC is required for proper fitment. Confirm the connector shape, terminal count, and bracket style against the original relay before replacement. Standard Ignition RY-4 uses a 4-terminal blade connection and a rectangular housing, so matching the original configuration is important for correct installation.

Quality Assurance

Standard Ignition manufactures this relay with composite housing materials to help withstand underhood heat and harsh operating conditions. Where specified, brass or copper contacts are used for wear resistance, and production follows TS16949 and ISO9001 quality systems for consistent part control from component to finished relay.