Heater motors

[Tony Stott]

Salut
Heater is from a Cortina with a single speed motor, did Cortina's ever have a 2 speed motor - any other motor fit the unit? - or am I going to have to adapt a radio contrl speed controller to work at 2 speeds?

[keith_h]

Re: Heater motors

I took the heater motor, matrix and control switch from a Sierra which gives me 3 speeds. I built an aluminium heater box with flaps to divert heat to the windscreen, the face or the feet. Drawings of the box have been put on the forum a long time ago. If you can't find them I think I still have them. If you are interested let me know

[Tony Stott]

Re: Heater motors

Ok, having looked at Fleabay images of the Cortina unit, I have an old heater motor which is 2 speed, originally destined for a 1/12 scale rc Customs Launch model, now she has a Stuart D10 steam lump etc, - I need to find it and ascertain if it will fit in the housing with a little adaptation etc.

[scott h]

Re: Heater motors

My Berlinetta has a standard Cortina heater wired through a Sierra 3 speed rotary switch. The secret is that you need a variable resistor between the switch and the fan motor. I took a resistor
from a car with a sliding 3 position control for the fan. This works by sliding a live contact to one of three separate contacts on a resistor block. I simply soldered the appropriate wires from the
switch to each contact and it works fine. Unfortunately I can't remember which car it came from as this was the early nineties but it was probably a Ford. One important point is that the resistor may heat up and should be mounted accordingly. There is lots of info about 12v fans on the internet because it turns out they are commonly found in computers.

[Tony Stott]

Re: Heater motors

any idea of the resistor value (or the pot), would need to be a high power one though, with a simple power transistor unit with a switched resistor bridge , i think that would work, need to knock one up and give it a try, my model club use a similar circuit (by me) to regulate the rotation speed of a lighthouse light ie in model form!

[scott h]

Re: Heater motors

Can't help I'm afraid. What I did works fine. As I said a quick search online gave lots of info about the maths involved. Wonder if anyone knows of any car that uses a three position sliding control for the fan speed? If you can find one in the breakers that's all you need.

[Dane_Rescueman]

Re: Heater motors

My old Cortina heater had a three position sliding resistor - I thought that this was standard fit in the Cortinas III - V. My heater casing rotted and fell apart so I made a new heater box out of ally, complete with fresh air scoop, and inserted a CBS heater inside. This comes with a three speed motor control and plumbs in to the same pipework.

[scott h]

Re: Heater motors

You have jogged my memory. I think I got the heater and control from the same Cortina but decided to convert the fan control to Sierra.

[Tony Stott]

Re: Heater motors

Found a resistor pack on fleabay, i'll have a play when it arrives and report back!

[Tony Stott]

Re: Heater motors

Ok Fiesta resistor module arrived, Having checked with multimeter, it is a 3 speed unit, also having used the sierra loom , bypassing the switch it will drive the heater motor at 3 speeds, now need to work out if i need the 2 lower speeds or the mid and top speed, but it does work, only problem it runs hot when in use so need to mount it carefully!

[greyV8pete]

Re: Heater motors

Ok Fiesta resistor module arrived, Having checked with multimeter, it is a 3 speed unit, also having used the sierra loom , bypassing the switch it will drive the heater motor at 3 speeds, now need to work out if i need the 2 lower speeds or the mid and top speed, but it does work, only problem it runs hot when in use so need to mount it carefully!

From memory on the Sierra the resistor module is clipped on top of the fan unit so it is in the full incoming air flow. Peter.

[chris_cussen]

Re: Heater motors

Yes, top of the motor is where mine is in lots of fresh air and not making contact with anything else.

[b_caswell]

Re: Heater motors

The resistor should only run hot when it's on the slower speeds as at full speed it should be by passed.

[Tony Stott]

Re: Heater motors

yep, discovered that having lashed up a crude loom to try it properly, now need to sort and install, with the module on the delivery side of the fan if at all possible!