AC issue, mode switch?

[marwood82]

my aircon is no longer working.

no matter what setting i put it on the blower fan wont come on.
i've changed the fuse but it didn't make any difference

im pretty sure the fan speed switch is working as you can hear the relays clicking when you switch to speeds 3 and 4.

my suspicion is the mode switch as im getting a hissing noise when i switch between modes.

does this seem a likely cause?

if i understood the diagrams correctly the mode switch supplies the power to the fan speed control and then to the blower motor so i guess if its not working properly then the fan wont start?

Simon.

[TheOriginalMrP]

There is an electrical connection on the mode switch so that is your first port of call. Check the block connector on the blower motor resistor as well as the motor terminals. You will hear air shifting about when operating the mode switch. It's only a problem if the hissing is continuous which means you have a vacuum pipe leaking. That would not stop the blower motor operating. There are also circuit breakers on the blower motor, 1 for speeds 1 and 2 and another for 3 and 4. I would check your blower motor earth and mode switch electrics.

Good luck!

[marwood82]

thanks, got the electrical tester out and there's power.

it seemed to be a duff connection as the spade connectors looked like they'd seen better days.
once those were replaced the motor then ran.

though its still not completely sorted as i have the following problem.

engine running, mode set to vent (though it happens whatever setting).

toggle fan speed to 1 = nothing
toggle fan speed to 2 = nothing
toggle fan speed to 3 = nothing
toggle fan speed to 4 = fan works fine.
toggle fan speed back to 3 = fan works fine (you can hear it slow down)
toggle fan speed back to 2 = fan works fine (you can hear it slow down)
toggle fan speed back to 1 = fan works fine (you can hear it slow down)

dodgy resistor??

[Guinney1971]

I've had a problem with mine ever since it came back from a restorers in 2008 (one of
those I'll get around to it jobs lol).

Fan only works on a couple of 'mode' settings (max, norm and bi-level), and only on
fan speed 4.

My AC needs sorting anyway, one of the pulley bearings is seized, it has no belt, and the
gas that was put in it in Norfolk how ever many years ago is long gone.

Oh, and only my pass window opens, yay for black interior cars in this heat...... :roll:

[TheOriginalMrP]

Hi Simon.
My bets lie on the resistor which controls the fan speeds. If it's running flat out then I'm confident that's your problem. Remove the block connector and 2 x 6mm hex screws hold it in. Remove and test with a multimeter.

Also test the block connector to see if you are getting continuity on all of the switch settings.
Not an expensive item to replace buddy.


About a tenner from Ed.

If it's not that it's back to the drawing board.

Cheers

Ben

[marwood82]

Guinney1971 Wrote:Oh, and only my pass window opens, yay for black interior cars in this heat...... :roll:

i have exactly the same problem at the moment

TheOriginalMrP Wrote:Hi Simon.
My bets lie on the resistor which controls the fan speeds. If it's running flat out then I'm confident that's your problem. Remove the block connector and 2 x 6mm hex screws hold it in. Remove and test with a multimeter.

i need to check the wiring. as my whole fan setup seems odd.

firstly the plastic box the evaporator and blower sit in is glued together not screwed and there seems to be a resistor that someones got from maplin actually on one of the wires that goes to what appears to be a second ground on the motor.
(odd but it did work when i first got the car)

what rating is the resistor ?

[stunned_monkey]

Sure it isn't a supression capacitor? The car is riddled with them from new.

[marwood82]

stunned_monkey Wrote:Sure it isn't a supression capacitor? The car is riddled with them from new.

Yeah i think your're right, the wiring for the resistor was stuck behind the carpet.

[marwood82]

i think im just going to replace both. the motor runs but its not making a great noise and looking inside it looks a little corroded.

and for the sake of 10-20 euro i may as well replace the resistor as well as that seems to be connected to the speed issue.

just to clarify, the 2 grounds on the bottom of the motor, 1 is for the motor itself and the other is for the resistor?

[Chris P]

Claire,
i have a spare pulley if you want it.

[Guinney1971]

ooh yes please Chris, thanks for that, will sort it out with you next time I see you