A lot of the earths are linked, there is a earth next to the fan blower as well.
The problem many suffer from is the wire inside the insulation actually rots causing major high resistance, items will then try to find a earth circuit through other items earths, a classic example being the rear lights which can go "disco" with a bad earth.
You could very well have more than just one bad earth, any electrical motor is VERY voltage sensitive so will show problems sooner than other things.
What precisely is the problem ?
tabetha