Thread: Advice on heater

Personally, from your description, I'd use solenoids, but skip the computer control. 1 button & 2 rocker switches......
Are your controls actually all-or-nothing? Most that use cables have some range of adjustment, but that would preclude you from using a solenoid to control them, you'd need a stepper motor or similar.

I'm not sure why you assume you can't control a solenoid with the FB? Output1->Relay->'noid extend, Output2->relay->'noid retract. (assuming latching solenoids)
A stepper motor is only marginally more difficult, using PWM (which seems to be even better supported on the v6)

I would think you would want to use linear actuators instead of solenoids. You will move the cable X distance and hold it there. This is what a linear actuator is designed to do. A solenoid, on the other hand, is designed to extend and retract quickly. To keep a solenoid extended you have to keep power applied to it. Not so with a linear actuator--remove power and it stays where you left it.

A linear actuator also operates more slowly that a solenoid--desirable for moving cable-operated heat & a/c controls.

How big of a throw is it for the cables? Like if you pull the cable X cm's, it goes from being fully opened to fully closed?

If it is a relatively short distance, then you can also use servos and PWM it. If that is not an option, then I agree with linear actuators. Little harder to setup and more expensive, but will work. Solenoids seem like more of a last resort.

A key issue is the force needed - unless you can replace the valve & flap with modern controlled equivalents (pneumatic or electric).
If too heavy, geared stepper motors (servos) etc may be cheaper if required.



Fan speed is usually changed thru resistors. You should be able to add a 3 speed resistor pack and switch without too much trouble. (Oh - it's a Mini - scrub the last "too"; else scrub out from without.)

Hmm ok, the throw is around an inch. One cable is complete open complete close, and the other for the tap is incremental. How much more expensive would a linear actuator be?
Would I be possibly better off trying to retro in an electric/vacuum water tap maybe?
Cheers for the responses.

Would trying to adapt something like this be possible or is that heading into analog outputs?

Seifer - are you intending to actuate the flap & valve direct rather than the cable?
[IE - much less force; rotational actuation only; remove cluttering cables and assembly (though OEM setup is nice as a fallback...).]

That is an electronic heater tap which appears to have the solenoid built in to it, i'm assuming it just responds to the input from the potentiometer.
Im fine with using a cable, i just figured an electronic tap would be simpler. The actual flap for moving the air from the cabin to the windshield would still operate via a cable.

I guess what im asking there is can fb output the equivalent of a potentiometers? ie via multiple relays?