heater panel lights citting out

[ukhozi]

Got a weird one.
Fitted a new bulb into the heated rear window knob, which as you know is a sod to do as it means a strip down of the centre console just the remove the switch which then has to be dismantlement and the bulb replaced, (soldered in) used small 12v Christa's tree bulb as the push in one are too long.
Now everything works BUT when I turn on the heater knob to heat and the AC cut out switch opens the backing lights go out and the ignition (battery logo) comes on on the dash. I think it may be an earth problem but if it is, where?.