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I'm having issues with the ventilation controls on my 1998 Ford Mondeo.

They are vacuum assisted and will not move from the default screen setting. Vacuum is ok at the drivers foot-well connection and all fuses are intact.

Is it a common problem?

I have now had two vehicles with the same issues.

Any ideas on how to fix it?

My local dealer only suggested leaving the car with them for a costly investigation.

John

From the "Ask Jack" archives - 14 December 2009

We are not aware of a specific fault but there could be any number of things causing the problem.

If the system works at idle but then resorts to the default screen setting once driving there may be a faulty one-way valve in the vacuum supply, this will probably be located in the engine bay.

These systems tend to feed vacuum to a computer controlled manifold that has switching solenoids.

There may be a power supply/electrical issue that is disabling the solenoid controller.

This may or may not be related to a fuse. If it is climate control, it might be worth attempting to reset the processor by disconnecting it for a minute or two and reconnecting it.

Also, a vacuum connection may have come disconnected or an actuator could be leaking, a trained ear can usually hear a vacuum leak from the area ( a slight sucking/hissing noise )

It may be worth putting you head under the dash and listing for this with the engine running.

Each individual vacuum circuit can also be checked with a Multi-vac (hand operated vacuum pump) by disconnecting the manifold and applying vacuum to each flap circuit.

This should cause the actuators to redirect ventilation and they should hold vacuum.

Hope it helps.