My air cond people have traced a leak to the evaporator coil and they tell me this could cost around $900 most of which will be labour.
Apparently the unit is behind the dash. Are they having a go at me?
And is there anything else they can check whilst the dash is down?

yes the evaprator core is behind the dash inside the heater box, so the dash needs to come out and heater box removed and opened up to change the evaporator core, so its a pretty involved job..

Thank you Troyman. Well the evaporator has been replaced at a cost of $900 and 2 days off road. All seems well except that the idle speed has been disturbed and is now very rough. Hopefully my own mechanic can fix that.