Resolved Wiring electric fan

[cbac89]

Hello all. Trying to connect my electric fan to a thermo trigger but i wired it slightly different than normal. For my relay i have the following:
86 - Trigger - from ignition switch
30 - battery with fuse
85 - to ground
87 - to fan positive wire
and the thermo switch is connected to the fan negative.

It was my understanding that the thermo switches act as a ground when they get to temp, so ideally this should work, but it isnt. What am i doing wrong?

The reason i did it this way was because i have a relay box with a shared ground and dont want to add another relay to an already messy engine compartment. Thanks for any help you can provide.

 

[KRUISR]

pin 86 can be an ignition trigger as opposed to direct battery power.
pin 30 - as you listed is battery power through a suitable fuse.
pin 87 - as you listed is power going to the fan.
pin 85 - as you mentioned is the ground for the relay. This goes to the temp sensor. If sensor is a 2 wire unit, one connects to pin 85 and one to body/chassis/engine ground. If sensor is a single wire type, then the body that the sensor threads into needs a ground wire to body, chassis or engine.

The fan motor is grounded separately on its own.

 

[AeroCoupe]

Short answer is the fan ground needs to go to the chassis or the negative on the battery. If the temp sensor is in fact just a switch and provides ground that needs to go to Pin 85 as mentioned above.

 

[cbac89]

Short answer is the fan ground needs to go to the chassis or the negative on the battery. If the temp sensor is in fact just a switch and provides ground that needs to go to Pin 85 as mentioned above.

Yep, thats correct. When i ran a meter to the thermo switch ground it was inconsistent. I dont think its a good enough ground to run the fan. A ended up installing another relay and it works now. thanks.