This sounds like a case of the air-conditioner freezing up over time. It can be caused by a few things, but essentially, it will start out cold and then gradually lose effectiveness till it's hardly blowing air at all, and that air is no longer cold.

It's caused by a build-up of ice in the system which blocks the air flow and prevents any further chilling of the air coming into it. To check this, next time it happens, jump out, open the bonnet and see if there's ice forming on the air-conditioning pipes under the bonnet. If that's the case, an air-conditioning specialist should be able to identify the problem and sort it.

We have asked Ford for an outlook on the availability of your diff, but so far haven't had a reply. If the diff is being done under warranty then wait it out, but if it's not and you're going to be charged for the diff I would take the car to a diff specialist and have them fix it.

Ford Australia customer service chief Stephen Kruk replies: "It is an industry known and understood phenomenon if the fuel provider does not have the right pumping equipment for a below-ground or above-ground tank. The basic principle behind being able to refuel LPG vehicles is that the pressure of the LPG at the refuelling station must be higher than the pressure of the LPG in the vehicle tank. We are happy to inspect the customer's vehicle to confirm it is working correctly."