Hi all, Ive been really lazy and need to mount my thermo fan switch after having it dangling around the steering column for a few months, i was wondering if it is possible to wire up the extra touch buttons to do something like this as they are a Normally open circuit and only closed while your finger is on the button. Is there some sort of relay that is click on/off if you get what i mean. (like use the touch button to activate then deactivate without holding it). Any ideas? Would be great to use the buttons for something as just one working for demister is really boring. Cheers Ben
If your any good with electronics I can shoot you a circuit I made to do exactly that. Re the relay, I looked for ages and couldn't find one for anything that even resembled a decent price.
why does a thermo fan need a switch, Ive just been looking at a mates wifes truck that had a switch on the fan as the only means of control shes cooked it and done a head gasket, put a stat on it so the fan is set and forget
Mines a fan override switch to turn on whenever i want, mainly for when i turn the A/C on. It still has the computer controlling it.
well i dont think a manual switch should be the only means of cooling control in a womens car for one (hence the gasket)!- no disrespect to the ladies out there and if u have a car and engine that likes laying a lot of rubber it is wise to have a manual switch to keep the temps down earlier and longer
Sorry for the delay guys. I based mine on this Circuits Page 9 Relay Toggle Circuit Using a 555 Timer This 555 timer circuit below toggles a relay when a button is pressed. Pins 2 and 6, the threshold and trigger inputs, are held at 1/2 the supply voltage by the two 10K resistors. When the output is high, the capacitor charges through the 100K resistor, and discharges when the output is low. When the button is pressed, the capacitor voltage is applied to pins 2 and 6 which causes the output to change to the opposite state. When the button is released, the capacitor will charge or discharge to the new level at the output (pin 3). The parts are not critical, the resistors can be somewhat higher or lower, but the 2 resistors at pins 2 and 6 should be equal values, and the resistor connected to the cap should be 10 times greater or more. Advantages of this circuit are the large hystersis range at the input which avoids false triggering, and only a few parts are needed for construction. One disadvantage is the relay may be engaged when power is first applied. To solve this problem, you could tie the reset line (pin 4) to another resistor/capacitor combination with the capacitor at ground and the resistor at the +V point. This will cause pin 4 to be held near ground for a short period which will reset the output when power is applied. The 100 ohm resistor and 100uF capacitor serve to filter noise on the supply line if the circuit is used in a automotive application. They may not be necessary. The circuit may work well without those parts.
still unsure why people dont just hardwire thermos. its not like itll cool it too much. thats what the thermostat is for.
