Proper current flow must consist of two things, voltage and amperage. Voltage may be compared to horsepower and current could be compared to torque. Voltage will help the fan run faster but it takes current to get it started. These two things depend greatly on one another and will always offset each other. When voltage goes down amperage will increase and when voltage goes up the fan will require less amperage.

Many things can contribute to voltage and amperage loss in an electrical system. The most common is the wiring is too small for the circuit or the current is routed through the circuit through too many devices or switches. In any high-amperage draw circuit, a relay should be used to help eliminate current drop. As the old saying goes ”the shortest distance between two points is a straight line,” which holds true with electricity. A relay mounted between the battery source and the fan will almost eliminate all current loss. No more ignition switch overheating and voltmeter fluctuations.

In most aftermarket engine control systems today we have a grounding wire or connection to operate an electric fan relay. These computers are normally programmed to a specific temperature for the computer to allow a ground trigger for the relay. A relay kit like the Painless 30109 PCM Fan Relay Kit is designed to be triggered by the PCM (ECM) and allow current flow directly from the battery source to the fan.

Air conditioning also plays a big part in the cooling of the engine and the cooling of the cabin. The fan needs to run when the engine is at operating temperature as well as when the A/C compressor is in operation. These two instances may not be at the same time. Painless Performance has developed a fan relay that will allow the fan to operate at a preset engine temperature as well as when the A/C compressor is turned on. This design will allow maximum cooling efficiency of the engine and A/C system.

The new Painless relay PN30114 (200/180 degree thermostat) and 30115 (185/170 degree thermostat) are easily installed and come with circuit protection, wiring, terminals, a thermostat, and easy-to-follow instructions.

12 Ways to Screw Up (or Not) Your Wiring Harness

We asked Dennis Overholser of Painless Wiring for some tips on how not to treat your wiring system. He said he didn’t have to look too far as the following examples he tells us happen far too frequently and can lead to disastrous results.

If you have a harness more than a couple of years old and are just now installing it in your ride, be safe and contact the manufacturer to be sure it has the upgrades needed to comply with your needs.

1. The proper way to strip and crimp terminals

Do not strip away too much insulation thereby leaving copper showing.

2. Using circuits designed for relays without the relay

Make sure ignition switch wires do not become severely burnt due to the electric fan and air conditioning power drawn directly through the switch rather than through a relay. A bank of relays will control all the high load circuits in the car. They prevent overloading the switches as well as the fuse block.

3. Installing a system smaller than the vehicle’s needs

Be careful not to add too many extra circuits on after the system is installed. This can cause excessive current draw through the fuse block and a possible major meltdown of the fuse block.

4. Improper grounds

Ground straps are very important yet many rodders make the common mistake of not reattaching a ground strap and servicing the engine. A proper ground cable from the engine to the frame is critical as is a ground cable connecting the frame to the body or a body support in the case of a fiberglass car. Junction blocks are another neat way to make sure the dash and accessories will be properly grounded.

5. Lack of proper wire supports and routing

A little time doing proper routing will make the underdash area neat and easily serviced. Insulated wire clips are a safe way to keep wires in their place.

6. Improper overall circuit protection