Fridge only works with thermostats/thermistors disconnected
crwdns2934249:0crwdne2934249:0:
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My 2007 (?) Bosch Logixx KTR18420GB/01 small simple fridge has been erratic in its temperature control for many months. Using an external thermometer and ice blocks from the freezer, it was possible to kept it in use.
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My 2007 (?) Bosch Logixx KTR18420GB/01 small simple fridge with 'Maxx Freedom Performance' has been erratic in its temperature control for many months. Using an external thermometer and ice blocks from the freezer, it was possible to keep it in use.
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I recently checked all the refrigerator components (PTC relay, start capacitors, pump windings, thermistor response (2 off), and some control board component (capacitors, triac, diode), but couldn't find any signifiant fault (I did change the 4uF start capacitor as it had dropped to 2.9uF and did re-soldered one iffy joint.
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I recently checked all the refrigerator components (PTC relay, start capacitors, pump windings, thermistor response (2 off), and some control board component (capacitors, triac, diode), but couldn't find any signifiant fault (I did change the 4uF start capacitor as it had dropped to 2.9uF (no difference) and re-soldered one iffy joint (no difference)
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By chance I found the pump would run and cool if I disconnected the two NTC thermistors (thermostats) with a starting wattage of 60W quickly dropping to 40W, as the start relay cut out.
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By chance I found the pump would run and cool if I disconnected the two NTC thermistors (thermostats) with a starting wattage of about 60W quickly dropping to about 40W, as the start relay cut out.
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But after exactly and reproducibly 15 mins, the pump stopped again.
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But after exactly (to 10 secs) and reproducibly 15 mins, the pump stopped again. Then it started again exactly 45min later and so continued in this safe mode at about +3C, I guess to protect the fridge contents. Do other fridges have this feature? why are there two thermistors? could I use a universal fridge thermistor?
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This is not a long term solution as the fridge will need a longer cooling time in summer or in heavy use and the only manual over-ride is to turn the fridge off and on again when it stops cooling to restart the cycle. (you can't change the on/off ratio by adjusting the temperature on the front panel)
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Any ideas what else I can do, given that most of the parts are obsolete and no service manual is available online.
Fridge only works with thermostats/thermistors disconnected
crwdns2934249:0crwdne2934249:0:
My 2007 (?) Bosch Logixx KTR18420GB/01 small simple fridge has been erratic in its temperature control for many months. Using an external thermometer and ice blocks from the freezer, it was possible to kept it in use.
I recently checked all the refrigerator components (PTC relay, start capacitors, pump windings, thermistor response (2 off), and some control board component (capacitors, triac, diode), but couldn't find any signifiant fault (I did change the 4uF start capacitor as it had dropped to 2.9uF and did re-soldered one iffy joint.
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Although the the pump would not run, the energy meter showed that the fridge was still using18W which was dissipated as heat in the control panel (not in the PTC relay ) as determined by an IR camera.
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By chance I found the pump would run and cool if I disconnected the two NTC thermistors (thermostats) with a starting wattage of 60W quickly dropping to 40W, as the start relay cut out.
-
But after 15 mins the pump stopped and the energy consumption went back to 18W, which was obviously a bit high for powering a few LED's and logic switches.
+
But after exactly and reproducibly 15 mins, the pump stopped again.
Any ideas what else I can do, given that most of the parts are obsolete and no service manual is available online.
Fridge only works with thermostats/thermistors disconnected
crwdns2934249:0crwdne2934249:0:
My 2007 (?) Bosch Logixx KTR18420GB/01 small simple fridge has been erratic in its temperature control for many months. Using an external thermometer and ice blocks from the freezer, it was possible to kept it in use.
I recently checked all the refrigerator components (PTC relay, start capacitors, pump windings, thermistor response (2 off), and some control board component (capacitors, triac, diode), but couldn't find any signifiant fault (I did change the 4uF start capacitor as it had dropped to 2.9uF and did re-soldered one iffy joint.
Although the the pump would not run, the energy meter showed that the fridge was still using18W which was dissipated as heat in the control panel (not in the PTC relay ) as determined by an IR camera.
By chance I found the pump would run and cool if I disconnected the two NTC thermistors (thermostats) with a starting wattage of 60W quickly dropping to 40W, as the start relay cut out.
But after 15 mins the pump stopped and the energy consumption went back to 18W, which was obviously a bit high for powering a few LED's and logic switches.
Any ideas what else I can do, given that most of the parts are obsolete and no service manual is available online.