I converted to an open cooling system and continue to have issues with the fan switch. The switch is a Napa fs113, wired to a relay. Switch will work for a short period of time and then die. When I test the relay, by-passing the switch grounding with jumper fan kicks on. On the relay when I go to ground with a circuit tester, I have a small amount of voltage? I want to keep the automatic switch. Any help is greatly appreciated.