fan relay

Or 30 and ground, this will tell you the electrics are working, it still won't tell you the fan is working.

Or not... I'd suggest not 30 because if the fan fuse blows... But that's where I'd go dual-colour LED - green if the thermo switch is on AND the fan has power, red if switch is on but no fan power. That solves both situations and desires.    Then I'd flash red if the "fan wasn't working", but that's a fun little sensing project in itself. (Easy if indoors and stationary, but not when outside and moving.) Hence a temp gauge or other temp sensor alert (which is after all, the bottom line - who cares if or why the fan isn't working - it's the overheating you need to know about ie, ignition timing, blocked radiator, leaks & low levels, blah di blah).

Sorry for the delay on getting back, my hot water heater went so I had to fix that yesterday. I played around with the relays for a few hoers on Monday and I have no idea why 87a is connected to ground. The fans work fine with or with out the 87a grounded. What I did notice is when the fan is not running 87a is grounded, as soon as the fan is energized to run, 87a looses it's ground. So at this time I have no idea why the schematic I have shows 87a going to a ground for this application.Playing the ultimate game every day

oldspark wrote: Not in series! In parallel, eg across the GND-switched 85 & 86 +12V. (Though preferably not from 86 - use another circuit as I discussed earlier.)

Oldspark I'm gonna have to go back and re-read your posts I'm alittle confused at this time. but I'm sure I'm going to have a lot of questions. MY knowledge on these relays very limited, but it is growing this forum is very nice. Playing the ultimate game every day