My 2.7i swap came with the mechanical fan deleted so I went with an electric fan. I had it running off of a thermostatic controller (temp probe in radiator) with a relay. Unfortunately, the controllers have a reputation for failing, which is what happened to me. The circuit board had continuity issues and the board kept losing power but I never knew if it did or did not have power because hearing the fan run with the engine running was impossible.
So last week I realized that the controller had shit the bed…mostly because I saw the temps shoot into the red and the car pissed coolant from a blown coolant passage. Fortunately the head gasket did not go- the gasket at the TB heater failed first (thank God).
Now I am trying to build a new fan controller based on a switch in the A/C fan port in the body of the radiator. Plan is to use either one or two 5-pin relays. I can either use a 2-relay system that has an override switch in parallel with the thermostat switch on a single-relay setup OR I can run 2 totally separate parallel relays – one thermostatically controlled and one manually controlled. A single will be easier to wire up but a double relay system has the benefit of redundancy.
Obviously the 30/51 will be fed with a fused 12V+ signal and terminal 85 will be grounded. Terminal 87 will feed the fan when triggered. The assistance comes in two areas: The use of the 87a terminal and setting up “indicator” or “status” lights associated with 87 & 87a.
So the new setup will use an 80*C switch trigger that goes into the A/C port in the radiator. It will supply the trigger to the 86 terminal on the relay. I can also run a simple toggle switch in parallel to the terminal 86 or I can run the second relay. Which would you recommend- two relays with discrete triggers or dual triggers run in parallel to a single relay?
Second question focuses on an indicator or status light. I would like to have a light that remains on when the relay is powered but not triggered by wiring the status light into the 87a terminal and then having it change color or illuminate when the relay is triggered and the 87 terminal fires. Ideally the “triggered” light would be tied across the coils of the fan but that would be too hard to wire up so this is a good (enough) indicator solution. I found something like these:
http://www.alliedelec.com/sloanled-255-12-r-g/70015146/
If I tie one color into the 87a to show power to the relay and the other color into the 87 terminal to show that the relay has been triggered, that should at least give me an idea of the status of the relay (though obviously not the actual fan), correct? And would that small LED require any sort of diode or resistor? It would be the only thing on the 87a terminal when the relay is not triggered but when wired in parallel with the high-draw accessory fan will it cause issues?
While this all makes sense to me in theory I just don’t understand circuits well enough to have full confidence in the schematic that I drew up in my head.
So last week I realized that the controller had shit the bed…mostly because I saw the temps shoot into the red and the car pissed coolant from a blown coolant passage. Fortunately the head gasket did not go- the gasket at the TB heater failed first (thank God).
Now I am trying to build a new fan controller based on a switch in the A/C fan port in the body of the radiator. Plan is to use either one or two 5-pin relays. I can either use a 2-relay system that has an override switch in parallel with the thermostat switch on a single-relay setup OR I can run 2 totally separate parallel relays – one thermostatically controlled and one manually controlled. A single will be easier to wire up but a double relay system has the benefit of redundancy.
Obviously the 30/51 will be fed with a fused 12V+ signal and terminal 85 will be grounded. Terminal 87 will feed the fan when triggered. The assistance comes in two areas: The use of the 87a terminal and setting up “indicator” or “status” lights associated with 87 & 87a.
So the new setup will use an 80*C switch trigger that goes into the A/C port in the radiator. It will supply the trigger to the 86 terminal on the relay. I can also run a simple toggle switch in parallel to the terminal 86 or I can run the second relay. Which would you recommend- two relays with discrete triggers or dual triggers run in parallel to a single relay?
Second question focuses on an indicator or status light. I would like to have a light that remains on when the relay is powered but not triggered by wiring the status light into the 87a terminal and then having it change color or illuminate when the relay is triggered and the 87 terminal fires. Ideally the “triggered” light would be tied across the coils of the fan but that would be too hard to wire up so this is a good (enough) indicator solution. I found something like these:
http://www.alliedelec.com/sloanled-255-12-r-g/70015146/
If I tie one color into the 87a to show power to the relay and the other color into the 87 terminal to show that the relay has been triggered, that should at least give me an idea of the status of the relay (though obviously not the actual fan), correct? And would that small LED require any sort of diode or resistor? It would be the only thing on the 87a terminal when the relay is not triggered but when wired in parallel with the high-draw accessory fan will it cause issues?
While this all makes sense to me in theory I just don’t understand circuits well enough to have full confidence in the schematic that I drew up in my head.