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[Webby the Bear]

Renault Megane came in today. Chap said that none of his fan blower settings worked. Tried them all out and yup, none of them worked.

The guy had already got the glove box out to gain access to the blower motor so just needed us to see if it was a new blower motor needed.

Was about to whip out my trusty multi meter and check for voltage going to the motor. But i thought, hang on, one of the mechanics is always banging on about the power probe so I thought I'd borrow it for this.

At first I was a bit unsure of how to use it but once I got the hang of it it was a piece of piss.

Simply connect it to the 12v ciggy socket and shove the 'sharp' end in to the connector wires whilst it's still connected (and the fan switch activated, on full blow in this case) showed three ground wires and one live wire with full battery voltage going to it. So new blower motor presumably.

One question though. . . And please bear in mind electrics aren't my forte. . . I know the very very very rough basics. . .

If I'd disconnected the connected, put my power probe on the live terminal of the motor and press the button, am I right in thinking the probe would have delivered battery voltage and I can manually activate the motor to check its function?

[Broomies Mate]

Rheostat I suspesct!!  Common on all French pieces of shit.

[Nick W]

There are 3 wires on a power probe: the battery connections, and an additional earth. If you're using the probe connected to the car's battery, you don't need the extra earth. But connecting it does allow you to power things separately, like to test your heater fan on the bench before you fit it. Or to operate the boot solenoid through the tailgate wiring on a Focus with the keys locked inside.

They're a very useful bit of kit, but you have to be careful that you don't put 12volts(24 on a truck) backwards across delicate components.

Sealey now do one with a basic display and oscilloscope which looks really tempting for sensor outputs. Although that will have to wait as I've just bought a better cordless impact wrench.

[Gaffers]

I must admit, I am very disappointed with the content of this thread given the title

[Rods2]

I must admit, I am very disappointed with the content of this thread given the title

Not half as much as your avatar!

[Webby the Bear]

Rheostat I suspesct!!  Common on all French pieces of shit.

Thanks Broomie.

Is a rheostat what I would call a resistor? It's there to reduce the voltage to the blower motor so you have lower speeds on the fan, correct?

If so, is the resistor part of the blower motor or lives somewhere separate?

Thing is I do know that he didn't have full speed. And the resistor is bypassed for full speed and gets a full 12v. As I had 12v coming in to the motor this surely says the motors toast???

[Webby the Bear]

There are 3 wires on a power probe: the battery connections, and an additional earth. If you're using the probe connected to the car's battery, you don't need the extra earth. But connecting it does allow you to power things separately, like to test your heater fan on the bench before you fit it. Or to operate the boot solenoid through the tailgate wiring on a Focus with the keys locked inside.

They're a very useful bit of kit, but you have to be careful that you don't put 12volts(24 on a truck) backwards across delicate components.

Sealey now do one with a basic display and oscilloscope which looks really tempting for sensor outputs. Although that will have to wait as I've just bought a better cordless impact wrench.

Thanks for the input Nick. Yeah, it has to be a 12v circuit otherwise you fry shit lol

I can't justify buying one at this stage cos we don't use it that often, there's two in the shop I can borrow and I am not 100% sure on all its functions....but I think I'll take the time to study it 

So as for the example above am I right in thinking that my 12v cigarette adapter was providing me a ground and that I could simply blast the disconnected blower motor with 1v and it should run?

[Webby the Bear]

I must admit, I am very disappointed with the content of this thread given the title

 

I promise my next thread title will be in the gen. Dis. Area and will be 'there's something inside mary' 

[Broomies Mate]

Rheostat I suspesct!!  Common on all French pieces of shit.

Thanks Broomie.

Is a rheostat what I would call a resistor? It's there to reduce the voltage to the blower motor so you have lower speeds on the fan, correct?

If so, is the resistor part of the blower motor or lives somewhere separate?

Thing is I do know that he didn't have full speed. And the resistor is bypassed for full speed and gets a full 12v. As I had 12v coming in to the motor this surely says the motors toast???

If you have been able to bypass the fan control switch on the dash and input 12v direct to the motor and it still doesn't spin, then yes, the motor is Donald.

Another way to prove/disprove the rheostat would be to proble the output to the motor from the switch with a multimeter and run the switch through it's various speed settings and view what output voltage there is.  If the switch is operating as it should, then hapy days.  You could even attach a small 12v lamp (not LED) and see if the brightness varies with switch operation.

[Webby the Bear]

Yeah, I was able to bypass it all as he had the glovebox out thus I could get to the connector.

Would I then simply disconnect the connector, put the PP on the live terminal and the cigarette lighter adapter plugged in, press "supply voltage" button and it would run?

[Webby the Bear]

...re the rheostat testing. . .

That means taking the climate control panel out, locating the connector and probe that for voltage whilst activating the different settings?

[Broomies Mate]

This is only an assumption, but the circuit should be as folows;

Battery > Fuse > Blower Control > Motor.

If you can get to the motor, you can get to the feed from the blower control (That's what is pluged into the motor).

You should therfore be able to probe the plug with a Multimeter set to DC and use a suitable 0V (Any fixing bolt or the like).

All of the above is completely irelievant if the car is CanBus or has a.n.other type of electrical wizardry going on.