A modular valve system having fixed valve ports with frame openings on the exterior of each port. Corresponding connectors or plugs are designed to fit within the valve ports and be locked in place by a clip passing through the framed openings and around the connector or plug. The internal valve component may be electrically or mechanically controlled. The modular valve system may be connected to a vehicle coolant system to control fluid flow to a heat exchanger or bypassing the heat exchanger.