Unsurprisingly the heating system in the Invacar was full of all manner of crud.  I'd already cleared out everything between the heat exchanger and the control box, but downstream of that still needed done.

My procedure here was (after repairing the duct connection to the cabin heater outlet) to insert a vacuum cleaner hose there, and turn both the demister and heater controls to on, having blocked off the normal heater inlet (stuffed a rag in the end of the heat exchanger).  This meant that air was drawn in through the demister vent, through the heater control box and out through the cabin vent.  I then went around tapping the ducting firmly with the handle of a screwdriver until I could no longer hear stuff rattling along the vacuum cleaner hose.
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Heating system cleaning

Added to 1973 AC Model 70 Restoration3 years ago

Unsurprisingly the heating system in the Invacar was full of all manner of crud. I'd already cleared out everything between the heat exchanger and the control box, but downstream of that still needed done.

My procedure here was (after repairing the duct connection to the cabin heater outlet) to insert a vacuum cleaner hose there, and turn both the demister and heater controls to on, having blocked off the normal heater inlet (stuffed a rag in the end of the heat exchanger). This meant that air was drawn in through the demister vent, through the heater control box and out through the cabin vent. I then went around tapping the ducting firmly with the handle of a screwdriver until I could no longer hear stuff rattling along the vacuum cleaner hose.

HUAWEI CLT-L09More Exif data

  • Manufacturer HUAWEI
  • Model CLT-L09
  • X Resolution 72 dpi
  • Y Resolution 72 dpi
  • Resolution Unit inches
  • Orientation 0
  • Software CLT-L09 9.0.0.163(C432E5R1P9)