So... you want it to work incorrectly? I'm confused, brother. The fan is supposed to be OFF at temperatures below 180F. The fan is supposed to turn on LOW at 180F. Then the fan is supposed to turn on HIGH at 195F. Im guessing that when the fan turned ON with key ON, the temp sensor was not working properly. Which schematic did you use for your installation? It may help us to help you.
Heres the original diagram for the Volvo controller. http://1bad6t.com/extra3/volvofan.gif I looked at the website of the installation that I used but it got deleted.I pretty much used an Escort fan with a Volvo controller with a BMW dual temperature switch. I thought the fan wasn't working properly since it would always turn on with the key on but like you mentioned maybe the temp switch wasn't working properly.
Ok. So if you notice, there is no key ON source in the schematic. The feed is 12+ at all times. That schematic will boil down like this at ALL TIMES (even with key OFF): Temp sensor less than 180F = both speeds OFF. Temp sensor more than 180F = LOW speed ON. Temp sensor more than 195F = HIGH speed ON. If you wire like this example, the added relay provides a feed that is ignition controlled. Does this make sense? If not, I can explain it a little more for you.
Sure, no problem. Lets look at the schematic you used: The feed for the fan comes from the top (connection A1). This feed is hot at all times, it is hooked directly to the battery (with a fuse inline, ofcourse). With the relays in this current position, the fan will stay OFF. Try and follow the circuits from A1; you cannot get to the fan in this state. Now, imagine the engine reaches 180F. This causes the B1 connection to get switched to ground (by the temp sensor, aka thermoswitch). The coil of the left hand relay is now a complete circuit, and so the relay switches. When the relay switches, it completes the circuit for the LOW speed circuit, and the fan turns on LOW. Now imagine the engine reaches 195F. This causes the B2 connection to get switched to ground now (B1 is still grounded, remember). This causes the right hand relay to operate, which makes the connection for the high speed circuit. Fan is now on HIGH. This circuit does not contain any inputs from key ON. I am not sure how you were getting the fans to turn on with the key using this circuit.
you were connecting two grounds. you needed to put test light to 12V and then to each side of the sensor.
