Cooling fan current consumption?

[Darius2]

Have had odd AC problems on my '99 C220CDi which have finally been traced to the main cooling fan not coming on. This is apparently because the control unit has failed with a burnt-out circuit. At 125 to replace, that's fine so far. But the guy who tested the fan by connecting it directly to a battery said it seemed to use a lot of current (the wires got hot - very scientific!), and suggested I replace the fan motor as well, as this might have caused the control unit to burn out. Obviously I don't want to do this unless it really is necessary - does anyone have an idea of how I could find out? (There's no mechanical resistance when you turn it by hand).

Many thanks

 

[Blobcat]

You could always provide a fused 12v supply direct to the fan and see if it spins up.

 

[Bolide]

Use the control unit to tag a high-current relay and feed the fan via the relay. If the fan's drawing lots of / too much current then let the relay be sacrificed rather than the control unit

Most big fans do pull a few amps - I've installed some that would burn out a regular relay

Nick Froome
www.w124.co.uk

 

[television]

The MB visco fan was a design made to use very low currents,(2 types) since the engine is providing the HP to drive it, the Visco is only a means of a clutch to engage it.
Back to the original question, yes they do use high currents, if you go to a web site and look at say Kenlowe fans and read the specs that will give you an idea of the currents used. Remember that high current devices do require very good connections, if the connection anywhere is poor, heat will be generated that will eventuallly lead to failure of the component supplying the power to the device.
Malcolm

 

[Darius2]

Thanks for these - sounds like the fan is probably OK. Might try the relay idea just in case though. Will let you know (impending baby permitting).
Darius

 

[kanda]

which fan are you refering to?
Ac Fan or Viscous Fan, they are 2 different units.
If its the AC fan then change the relay to a better one.

 

[television]

which fan are you refering to?
Ac Fan or Viscous Fan, they are 2 different units.
If its the AC fan then change the relay to a better one.

There are infact three types, the first was the Visco clutch (non electric),then the engine fan with a electric clutch (low current)operated by a simple sender on the front top of engine, and the fans on the rad and aircon, these are high current.

malcolm

 

[Darius2]

I was referring to the main large radiator fan. I understood that the AC on this model doesn't have a separate cooling fan.

 

[television]

I was referring to the main large radiator fan. I understood that the AC on this model doesn't have a separate cooling fan.

OK is the fan mounted on the engine, or is it mounted on the radiator ass;why not put up the first 6 numbers of the VIN.

Malcolm

 

[Darius2]

The fan is mounted on the radiator assembly.
D