I have an vectra 52 plate ?

Below front windscreen, you have what is called a plenum chamber. It is where the Engine Control Unit is, and the polen filter. It has drain holes, they get blocked, Open bonnet, look towards screen, you possibly have a plastic facia with holes in it, possibly a rubber strip around the front end of it, if so, try pulling the rubber strip off. The plastic cover should lift, if you can, I think on your car, polen filter is to the left, from front. You will probably find the chamber full of water. Not sure where the drain holes are, depending on access to chamber, you need to find drain holes and clear them. On my car, I have battery in the chamber, with 1 drain below the battery holder, so it all has to come out to clear. Will be differnt for yours, but would think that is the problem. If it is, you then need to dry the car out, a good way, is to run the air-con at coldest, the moisture will condens on the evaporator and drain away, as long as your evaporator drain is clear, running air con, should give you a puddle under the car, that is from the evaporator drain.

SD
November 2012