I would notice it in slight coolant loss but it was something you had to closely monitor. Additionally, the condensation on the window was on the driver's side of the car, which I think would be your passenger side in the UK. This would happen immediately after the car was shut down, and was sitting. When you wiped it off of the window it would more smear than wipe off like regular water condensation. You have to be absolutely certain because before it pools in the foot wells it is absorbed by all of the carpet, and insulation. Additionally they put the air bag control module right under the heater core HVAC box. It really depends where the coolant decides to come out of the HVAC box which is semi sealed whether it lands on the right or left side of the car. But again before it gets in the foot wells it soaks the carpet, insulation and a ton of wiring harnesses sitting right under the HVAC box.