This Bosch series 4 heat pump dryer continues its program for hours without finishing or drying the clothes. No errors on the display. This generally means blocked airflow through the heat exchangers.

Heat pump tumble dryers are a fully closed loop clothes drying solution which means they use less electricity to dry clothes compared to condensing or venting dryers. But they have one weakness, their fine finned heat exchangers. Over time they can build up lint in front of the exchangers reducing there performance. This Bosch series 4 is rated as self cleaning which may well be true for the cold side heat exchanger but the rear one clearly isn't as we find out.


0:00 Intro
1:30 Disassembly
12:28 Removing heat exchanger cover
14:50 Lint on exchangers
15:37 Cleaning heat exchangers
19:00 Reassembly
31:56 Repair or give away
33:33 Testing
34:11 Fixed and working