Suzuki Vitara heater fan stopped working

Hi

I have a 2009 Suzuki Vitara and the heater fan has stopped working. I've
checked fuses and tried another relay - no good. I've ran a wire direct from
the battery to the heater motor and it spins, so I'm assuming the motor is ok?

I've put a multimeter on the connector to the heater and its reading 12volts on
one side, and a variable reading on the other between 1 and 5 volts -
deepending on how high I've got the heater switch on.  Not sure what to
make of this as my knowledge of car electrics is very limited!

Any help would be really appreciated.

Smiffy