Thanks for your input, this looks like it could work, my one reservation is the supply voltage to activate the switch, it's showing "250Vac/dc" on the specification?
The switch is activated by vacuum.
It's capable of switching 2 Amps at up to 250 Volt, ac or dc.
You probably need a relay as well to handle the pump current.
I used a MES DEA pump on my Scirocco; Small, quiet, and has all the controlls built in. Quite expensive, but designed for the job. I think they spammed the forum a while back.
This is the current version; http://www.cebi.com/cebi/content/index_ ... 158&info=1
I don't know what kind of pump you have now, but many people will be put off by unpleasant noises in an otherwise very quiet vehicle.