cosworth heater control system.

[dom123]

can someone tell me the layout of the heater control regarding how they work... basically mines a aircon model, and intermitantly the heater seting no3 has stoped working on both the normal fan side and also the recirc side...

im not going to replace things for the sake of it so i want to understand how it works in the first place so i can check it all, as i'm a sparky...

heres my guess and i'm talking about the normal fan side...
is it the case that theres a wire going from each speed seting on the back of the switch to the fuse box, where theres 3 fuses and 3 relays then these 3 outputs going to the fan motor? i have no idea how the fans motors wire up theres like a actuator on the side god knows what that does, ive got a 4-5 pin plug in the top centre of the fan box, i think thats the main connector, but these some other wires connecting by the actuator are they for the air con, or the recirc, what does the recirc actually to the system??


sorry guys i like to understand how the system is ment work, then its easy to repair!!

cheers

[TEREX]

i dont know how they work but from looking at previous topics/threads its pointing towards the fusebox not being right, the control might be fine but getting no feed back to the fan through the box, try and bypass it to see if it works then

[dom123]

thanks for your reply, does any one have a pin out, or a layout of the fusebox?
or a st wiring diagram?
cheers

[igotblueblood]

Heater works fine in my new motor Dom

[TEREX]

dont know if this is any help to you ,

http://www.escortrscosworth.com/foru...ead.php?t=8536

[Cossie col]

would like to no more about this aswell as mine wont blow air onto windscreen but knob spins round freely but i cant be assed to take it apart as thought dash might have to come out

[kjc300]

If fan speed 3 goes dicky then it's generally the fusebox as it gets a full 12v supply from the fusebox, via the fuse. Speed 1 & 2 go through a resistor pack which is on the fan assy itself (resistor pack can be replaced apparently).


The actual fusebox takes about ten mins to remove. Take a photo of all the relays and fuses, then you can just unclip the plastics from the circuit boards. Check over all of the solder joints and resolder any dodgy looking ones.

My girlfriends normal esc had this prob and I did it the other day, the one I thought was the culprit was one of the fuse pins. Fixed it a treat!!


Not really too much else to go wrong if the fan itself works (stick 12v across it), and you can check the 3 speed switch easily too (just bridge the connections).

[ossie cossie]

that is exactly what happened to mine. i have pics of the resistor pack i will put up later.

[dom123]

thanks guys, theres no way i'm replacing the whole fuse box just for one connection! i cant say ive seen a resistor pack,

is it the case that the the fuse box sends out the power to the switch via a fuse, then the switch sends 12v direct to fan speed 3 and 12volts direct to the resistors ontop of the fan box for fan speed 1 and 2?

ii know i could work this out how to fix this in half hour if i just could understand how its was designed to work circuit wise.

[dom123]

Heater works fine in my new motor Dom

come on mate, what do you really think of the m3, i bet your well bored of it have you put it on a dyno? my mate did and it made 260bhp, he look like he was going to cry!!

[igotblueblood]

come on mate, what do you really think of the m3, i bet your well bored of it have you put it on a dyno? my mate did and it made 260bhp, he look like he was going to cry!!

I love it Dom. Not as quick as the escort in a straight line but in a race involving corners it would eat it alive; the best handling car I have ever driven!!!
Doesn't have the looks or presence of the escort but then you can't see that when your driving anyway
Sorry I can't offer any suggestions on the heater front

[kjc300]

thanks guys, theres no way i'm replacing the whole fuse box just for one connection! i cant say ive seen a resistor pack,

is it the case that the the fuse box sends out the power to the switch via a fuse, then the switch sends 12v direct to fan speed 3 and 12volts direct to the resistors ontop of the fan box for fan speed 1 and 2?

ii know i could work this out how to fix this in half hour if i just could understand how its was designed to work circuit wise.

That's right Dom.

[Dave_M]

Dom

For a sparky, repairing your fusebox if that's the culpritt should be pretty easy. I did an electronics apprenticeship about 20 years ago, but haven't used it other than a few hobby projects since. Have a search - I did a thread on what I did. Takes 10 minutes to get the fusebox out of the car, then probably an afternoon to repair it, and 10 minutes to put it back in car.

Dave

[dom123]

ive had a play today and when i pushed on the fuse front on the fuse box the heaters come on, so ive whipped out the fuse box and striped it down i couldnt see anything wrong with it, but you cant get between the circuit boards which is annoying, but i did find dirty pins on relay r26 and relay r13 does anyone know what they do? r26 does have big pins it must be for a heavy load.

[The Radman]

r13 sidelights,26 ign switch