Details showing how to wire Infinitybox MASTERCELL inputs to a Trinary switch.

Trinary Switch

Okay guys, we get asked this question a lot.  How do you wire a trinary switch on a Vintage Air Gen-IV with the Infinitybox system?  It is a good question.  We’re packing a lot into this blog post so hang on.  This post is only going to cover wiring the cooling fan part of the trinary switch.  The rest of the wiring is going to follow the directions given to you with the Vintage Air Kit.  That being said, you must carefully read and understand all of the installation instructions that came with your heating & air-conditioning kit.

Before we get too far, it is important to understand what a trinary switch does.  It is a safety switch for air-conditioning systems.  It is a three-function switch (tri-nary).  It automatically shuts off the power to the air-conditioning clutch if the refrigerant pressure gets too high or too low.  It will also automatically turn on the engine cooling fan when the compressor is running.  The Vintage Air guys have a great video featuring Rick Love talking specifics about Trinary Switches.  You can see that here.

You can see a more detailed picture of the Vintage Air wiring diagram in the picture below.

Wiring diagram from Vintage Air for Trinary Switch

Wiring diagram from Vintage Air for Trinary Switch

Your Infinitybox system is going to control your cooling fan.  There is a MASTERCELL input that connects to a thermostatic switch on your engine.  When the coolant temperature exceeds a set point (usually around 180 F), this temperature switch closes and grounds the MASTERCELL input for the cooling fan.  When this happens, the MASTERCELL sends a command to the front POWERCELL to turn on the cooling fan.  We’ve blogged about controlling fans before.  This link will take you to this blog post.  

When you’re installing air-conditioning in a car, you want the cooling fan to turn on under two conditions.  First, when the coolant temperature exceeds the set point of the thermostatic switch.  Second, you want the cooling fan to turn on when the A/C clutch is running.  Running the air-conditioning compressor increases the load on the engine.  Also, you have to make sure that you have good air flow through the condenser to make sure that the refrigerant system is working efficiently and safely.

Take a close look at the wiring diagram from Vintage Air.  The part of the diagram that we’re going to focus on only relates to the cooling fan wiring.  You are going to wire the A/C thermostat through one set of contacts on the trinary switch to the A/C clutch.  The Infinitybox system won’t get in the middle of this part of the circuit.  If the refrigerant pressure gets too high or too low, it will disconnect power to the A/C clutch for safety.

The fan part of the circuit is what we are discussing.  There are a pair of blue wires on the trinary switch.  These are the contacts for the cooling fan.  One of the blue wires connects to ground.  Either of the blue wires will work for this ground connection.  In the Vintage Air diagram, you will see that the blue wire on the trinary switch is used to ground switch the coil of the cooling fan relay.  When the pressure of the refrigerant in the system exceeds the set point of the trinary switch it will close its contacts and connect the fan trigger to ground.

With your Infinitybox system, there are no relays.  The MASTERCELL is your trigger and the POWERCELL turns on the power to the fan.  The following diagram will show you how to wire the fan contacts of the trinary switch to the MASTERCELL input for the cooling fan.

Details showing how to wire Infinitybox MASTERCELL inputs to a Trinary switch.

Details showing how to wire Infinitybox MASTERCELL inputs to a Trinary switch.

You will note that the trinary switch is wired in parallel with the thermostatic switch installed on the engine.  That way the cooling fan will turn on if either the coolant temperature is high or if the A/C compressor is running.  You can splice the trinary wire anywhere into the MASTERCELL cooling fan input wire.  You can splice these wires together at the MASTERCELL connector.  You can splice the two wires together in the connector going onto the thermostatic switch.  Electrically, they just need to be wired in parallel.

You can download a PDF copy of this wiring diagram by clicking this link.  Please contact our technical support team if you have any questions about wiring your cooling fan trigger into your trinary switch.