How to wire a relay

A relay is simply a mechanical control switch with a low current control switching a high current load. If you hit the key to start your car, the low amperage key switch grounds the solenoid side of the relay and closes the switch side and allows high current flow to the starter. The normal amperage for a starter is relatively high and wouldn't be acceptable flowing through the ignition switch. Now! Having said that, what are you up to?

Hazard,
here is a link and some information that I found online about your relay.
Read this and it might help you with your problem.

Make sure that you follow safety procedures.

Good Luck,
Cory

Fan Blower Controls

Problem: Fan will not come on in the "ON" position or your fan will not come on when you turn the thermostat down in the air conditioning mode.

Purpose of the Fan Center Relay: The purpose of the fan center relay is to provide low voltage control (24 Volts) of line voltage circuits (110 volts) and can be used to control two-speed blower motors and auxiliary circuits in heating or cooling equipment. Many of the newer furnaces do not have fan center relays, but many of the older furnaces and some new furnaces still do. You would need to look inside your furnace to determine if you have a fan center relay. Some of the relays are attached to a junction box where the power comes into the furnace, and others are located in the blower compartment attached to the blower housing. You might not have the relay that we sell below. Many of the newer furnaces are control by electronic circuit boards.

Troubleshooting procedure:
1. Make sure that your furnace switch is "ON" the furnace blower compartment door is on and secure. Move the lever on the thermostat to the "ON" position. The fan blower should come on. If it doesn't then you probably have loose or burnt wires in behind the relay or you may need a new fan relay or circuit board.

2. Many times wires are either loose or burnt behind the fan center relay. First make sure your furnace power is turned off. Remove the fan center relay and inspect it for loose or burnt wires. Repair wires and reinstall fan center relay. Turn the power to the furnace back "ON." Hopefully you have fixed the problem!

3. With the furnace on use a multimeter set to AC Volts, to test between terminals "R" and "C." You should get a voltage reading of approximately 24 volts AC. If you do not get any voltage reading, your low voltage transformer might need replacing or you are not getting high voltage to power the transformer. Sometimes furnace manufacturer's connect the furnaces transformer through the limit control so if your furnace over heats or if the limit is stuck open then you will not get power to the transformer. There are quiet a few variables that can occur to cause furnace problems. I believe I have covered the main problems. If you have the fan center relay like we sell below the low voltage transformer is combined with the fan relay. Below we have pictures of the fan center relay with an opportunity for you to purchase. This relay will work on motors up to 3/4 horse power.