Some of this may be of help.
Allan
Printable View
Some of this may be of help.
Allan
It might pay to get a snakescope or Borescope and have a good look at the evaporator before pulling it right out, but yes you will have to go to an a/c place and get the gas sucked out, then pull the whole unit across under the dash out to clean it..
think you'll need a bit more than a dyson I used 2 cans of degreaser on mine and ended up chucking it down the tip.