Position 1 & 2 there's no change. 3 & 4 work fine, what do I need to replace (apart from the car!)

heater resistor pack known failure point when some settings are lost. 2 screws i believe tho never done one myself

Just popped out an errand, and now positions 1 & 2 are working so obvious intermittent. Is it likely the same diagnosis of a faulty resister? I thought once an electrical component like a resister had gone, that was it?

Very likely the resistor pack on it's way out. It's a wire wound resistor and they can sometimes be intermittent before finally giving up. 

2 hours ago, Jimpster said:

... 2 screws i believe tho never done one myself

2 screws 🤣🤣🤣

 

have fun getting the glovebox back in, mine was a pain after doing cabin filter

Finally got the resistor replaced today, good to have blower position 1 & 2 back in operation. As you can see, the original one looks decidedly crusty! Whilst he was in the area, also treated the old girl to a new pollen filter. We think the old one was the original, so I suppose not bad for almost 20 years service...