Air cooled heating – adjusting

Following on from last week’s article about air cooled heating, let’s get on with adjusting it.

Tools and parts

  • Items similar to – scissors, wire cutters, Stanley knife, pliers and other cutting, pulling and squashing devices
  • Axle stands or other way of lifting the vehicle enough to get underneath safely
  • 6mm spanner or socket
  • Screwdriver
  • A friend, they won’t get dirty or need to roll underneath
  • Protective items for clothing, gloves, goggles / safety glasses

Checking

Get the vehicle far enough and safely enough in the air that you can crawl underneath and still safely operate tools.

Disconnect the battery. This is optional but safe.

Take ALL of the tools with you otherwise you end up doing a lot of sit ups going to fetch the above items.

Between the rear wheels at the back of the Y shaped J tube and heading into the heat exchangers, you will see two flaps, one on either side. These control the hot air coming forwards from the engine into the J tube and up to the front of the vehicle. If required, have your friend sit in the front and move the red levers up and down – look for movement underneath!

When both levers are moving, you should see a thin metal cable moving a flap that is about 50mm long and there should be a spring and a bolt. The arm should be moving freely forwards and backwards. Most commonly the cable is either missing or jammed.

If the cable is missing, get a new set! If the cable is jammed, get some lubricant on it and try again later. Manually move the bolt using pliers and see if the cable is free but the bolt is jammed. If required, detach the cable and verify which piece is jammed. Once all is moving, check that the control arm is as far forward as it can go when the cable has the slack taken up and the level on the dash is fully open. Similarly the level at the other extreme on the dashboard should allow the bolt to fully close the flap.

Adjust the slack on the cable using the 6mm spanner / socket, release the bolt, use pliers to take up the tension and tighten again. This actually needs doing regularly.

Thank your friend kindly and let them get on with something less interesting than fixing the heating on your vehicle.

As you are under there, don’t forget to wire brush and the loose dirt, muck and other unwanted bits then paint and underseal, especially on the heating pipes.

Follow all along from the front of the heat exchangers, along the J tube, the main tube in the middle, up and over the beam and up to the totem pole. Look for holes, leaks and missing insulation. Fix them all.

Crawl out from under the vehicle, stretch, curse if required, dust yourself down, get the axle stands off, reconnect the battery and celebrate by moving the levers on the dash of your working heating.

Remove the socks from the air vents on the dash (a popular way of stopping the draughts in the 90s), start the engine and feel more heat than before. If it is still not HOT once the engine is up to temperature then you still have air leaks in between the heat exchangers and the cab. Troubleshoot every join, seal every incorrect hole and check every flap. Come along to a club meeting and we can all take a look together!