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Introduction |
| My ~20year small simple (no defrost etc ) under-counter fridge (Bosch logixx Easy access Maxx Freedom Performance) became more erratic over several months. If it was too warm (flashing LED's) there is a 'super' button to press to turn on the compressor, but this no longer worked. | | First I replaced the 4uF start pump capacitor (£9) as it was out of spec (2.8uF), but that made no difference. Then I replaced the pump ptc thermistor relay (£13) as it was marked 25ohms and measured 45ohms. But even a new one measured 38ohm, so that made no difference. The pump coils' resistances seemed satisfactory (15 and 48 and 63ohmskohms). The fridge's thermostat (thermistors) also seemed OK (about 12 and15Kohms at 10C) and went up in resistance when the temperature went down. | | | Thus by process of elimination, it must have been the control board (the most expensive item up to £300 if you can find one). | | | By chance, I found that when you disconnect the two thermistors (one in the fridge and one outside I think), the fridge starts working again. On the downside it now works on an internal timer by turning on for 15mins then off for 45 mins irrespective of the temperature, (25% duty cycle) ie if the control board thinks the temperature sensors have failed it goes into a 'safe mode' to protect the fridge contents. (I don't know if other fridges do this- I could find nothing on the internet). | | In winter this makes the fridge too cold at 0C, but by putting the fridge on a mains timer e.g. to turn off overnight, you canI could manage the temperature better. Conversely, if the fridge iswas too warm you canI could manually (or with a mains timer) turn it off and on again to start the cooling. | | | This guide tells you how to fairly easily disconnect the temperature sensors (thermistors) so you can still use the fridge until a replacement/repair is possible. | | Another possibility thatLater, I haven't tried is to attachcontrolled the temperature automatically by buying an externalSTC1000 temperature controller like a STC1000(£8.50 on eBay) which should work on any fridge or freezer with a broken controller.
These external controllers are normally bought by people brewing beer that want good temperatureto better control (heating and cooling)fridges, freezers etc. |
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