Connections. First, make sure that all of the connections are correct by aligning Tip to + on the connector ends. Also ensure that none of the connectors are loose. Also, and this is very important, it is common to plug everything together, get it all working, and then going back and unplug and re-plug while rerouting wires. When doing this, ensure that the connections are reconnected properly.
Power Supply. If the products still are not working, ensure that the power supply is turned up to at least 5 to 7 V - this is done with the slide switch on the power supply. If you want to test the power supply, when it is not under load (fans are not connected), the power supply will output around 18VDC on any of the settings. If your voltmeter provides this reading, the power supply is operating normally. Also, the failure rates on our power supplies are extremely low (well under .5%) so if there is a problem, it most likely is not with the power supply.
The second issue with power supplies is to ensure that the milliamp rating is within tolerances. Now this typically will not be the reason the units/fans will not turn, but it can lead to long term failures. One simple test if the power supply may be 'overworked' is if the unit gets extremely warm after a few hours of use. The units will normally be warm but you should still be able to hold it in your hand without discomfort.
Further Troubleshooting. If the connections are correct and the power supply is set properly, the next thing is remove any 'intermediary' items (y-cables, temp controllers, etc.) and try to plug the units to the power supply directly.
Fan Failure. If you have read this far, then you have probably experienced a failure in the fans. Our failure rates on our fans are also well below 'acceptable' failure rates but no manufacturing process is perfect. We still however experience more failures due to polarity reversals than true manufacturing defects. The real problem with reversing polarity is that it only takes a split second, and a slight misalignment of the pins, and the fans can be damaged. Most likely, if you see a little spark or arching of power, that means polarity was just reversed. Now sometimes the fans will run for a few seconds or minutes after being damaged but usually a polarity reversal usually means that the fans will need to be replaced.
No Secret Cures. If you been through the above and the fans are still not working, there are no secret cures for fans not working. If your fans still are not working, please be in contact by using the Warranty & Returns Form and we will arrange replacement fans. With most of our products, we can simply send replacement fans and this way you do not need to return anything to us.