Heater air distribution

[kellyhenocq]

The system works fine under most conditions but, after a few seconds, when I boot it in a high gear the heater air distribution changes. I have checked the vacuum system between the inlet manifold and reservoir under the nearside wing and have found no leaks.

Having owned an old Ford Pop. with vacuum wipers I understand the lack of suck when running under high load so I wonder if what happens in my M100 is normal.

Can anyone confirm that their heater air distribution changes when you accelerate under load for a few seconds or if it is a real problem let me know how to fix it??

[Brit-Car-Nut]

I believe that under heavy load (wide open throttle), the vacuum drops and the heater valve opens up to make heat. The valve turns off when vacuum is applied.

If that is your problem, there are one-way vacuum check valves available - Ford US used them in the mid '70s on their full sized cars - LTD, Galaxie and similar.

I haven't looked for any in a long time, but eBay seems to have lots of bizarre old parts.

[DeanG]

I have a vacume leak somewhere in my system. It is most annoying when running the A/C. Anyway the M100 has a check valve like (but not actually a check valve) thing in one of the vacume lines under the dash on the drivers (LHD) side. Check valves should be available at any good parts store.

[Andy_J]

Could be a problem with the vacume accumulator. This is upunder the clam on the lefthand side behind the left front wheel arch liner. The vacume accumulator is there to prevent loss f vacume in the air distribution system when the car is on boost