Hi
Try resetting remote, Turn key to position two in ignition and press both button's on key at same time....All doors should lock then unlock. If that does not work it could be the transponder in the key, cost's around £90 for a new one . Heater/aircon.... Try changing the pollen filter to allow hot/cold air into the cab.... situated at back of centre console glove box side (which you have to remove to get to) cost's about £15 and most place's you have to order them.
paul
December 2010