Hi. I have a MK2 1.6 petrol focus. I'm having trouble starting the car if the blowers are on. If I leave them on 3/4 and try to start the car it.just turns over and won't kick in, but if I turn them off or on 1 the car will start. I presumed this was a battery issue but IV had the battery tested and they seemed to think it was okay( orange light on drop test not red). You guys had anything similar before?

I have the same car, it'll start with everything turned on! My gut says that despite your battery test, a new battery will sort you out...

Cheers I'll give that a try then.

18 hours ago, Wood.. said:

 had the battery tested and they seemed to think it was okay( orange light on drop test not red). You guys had anything similar before?

If the battery was ok then the orange light shouldn't have come on this means that the battery isn't ok and the person who tested the battery shouldn't think the battery is ok he should know that the battery isn't ok with a orage light after testing

this might not be relevant. On Mk5 Escorts there was a common problem with soldering of connections in the main fuse/relay box inside the car. Often this would be apparent with poor starting. starter motor span the engine at the correct speed but electronic ignition module was getting low voltage / erratic voltage. Once started they ran fine. The cure for this was to rewire the power supply to the electronic ignition module bypassing the fuse box. 

I am thinking maybe poor connection somewhere in the ignition system power supply and the additional load of fan etc pulls the voltage down just a bit too low for the ignition coils to work. I don't know much about how the ignition system works/how it is wired up on your car. On the Escort it could be proven just by running one piece of wire from the live battery terminal to the live supply on the electronic ignition module (for testing /proving the fault - obviously for permanent fix it then needed to be wired so that it was not live 24/7 and to have a fuse somewhere).