I have a technical query on my Bosch upright freezer and would really
like a chat with a domestic refrigeration engineer to check my fault
A circuit diagram of the cabinet wiring and sensors for a GSU3401GB/52
would be really helpful.
Reward would be considered as I'm am close to being at the end of my tether.
It is possibly about 10 years old. I bought it second hand about 8 years
ago and it has worked flawlessly until last October when it froze up.
The problem is in the return lead from the defrost heater. The switched
live on the heater is driven by a triac and is working - it switches on
every 12 hrs and 42 minutes for about 32 minutes. The compressor
switches off for that period via another triac. The return lead from the
heater goes via a 2 pin connector into the case wiring and the other pin
on that connector goes to neutral. As far as I can measure, the two pins
on that connector have >20Mohms and so not current ever passes through
the defrost heater element (which measures about 290 ohms) which makes
it designed for about 200 watts output.
Whatever this two pin connector is for I cannot find it on the spare
The overall effect is that over about 3 months the evaporator freezes up
solid and needs 24hrs or more to thaw meaning we have to move everything
out into a chest freezer.
Thanks for your offer of help but I possibly need someone who is used to
working on these new(ish) computer controlled freezers.
The older motor driven clock motor type defrost timers were so much
easier and simpler to understand.
Frost free are shit. Too much to go wrong. The older units with a simple
thermostat ran until the compressor packed in or the insulation failed. The
very cheap Zanussi standby freezer in the garage gets used every Xmas and it
must be 15 years old. Insulation is shagged, but it still works.
I'm sorry I can't help you.
If you give up, please buy a conventional freezer.
Thanks for replying. I cannot agree. This frost free machine has been
perfect for years. Now something has gone wrong and I'm trying to
analyse the fault, replace or modify it so that it continues to be
(near) perfect again.
I have two conventional freezers and defrosting is a PITA
I defrost the freezer compartment in our conventional fridge freezer every 3
months. It takes 20 minutes using a hair drier. This gives me the
opportunity to give it a clean and chuck away any food that has been there
for too long. I do not regard this as being a PITA.
Frost free has: timer, stat. defrost heater, fan PCB etc and all of the
stuff that you are having problems with. Sensor!?
My conventional only has a stat to go wrong. ?12 off the net and dead easy
Apart from refrigerant leaks and compressor failure, that is all to go
I hope you get your problem sorted.
The mystery component has been identified as a thermal fuse and is on
order. Meanwhile a jury rigged solution with a cartridge fuse is under
test whilst a pc logs the behaviour for analysis in the morning.
Well on the way to a solution I think.
I don't think the connector is bad. I want to know what is on the other
end of it and what its function is.
Logically is should be some sort of a switch, fuse or a temperature
operated switch. It has to pass the defrost heater current around 1 amp
So before I just short it out, I'd rather know what it is supposed to do
and assess the risks of bypassing it.
So what I want is in the subject line. First hand experience on the
principles used in this product and therefore to understand why the
heater element is not simply returned to neutral.
There is a post on UK Whitegoods that references a thermal fuse for the
defrost heater. That post says it is pushed into the evaporator fins.
Post also says it it not shown on exploded parts list but they give the
number as 00617855.
A search on this part shows a thermal fuse terminating in a white 2 pin
Lee, You are a star. Thank you
Although I had searched UKwhite goods forum, nothing came up for my
model number but as you say there are other results that point to my
problem once I search for thermal fuse. A post there also explained
another observation in that a secondary heater in the drain tray also
stays on for a further 10 mins after the main heater goes off. This not
on explains my logged behaviour data but explains the fourth triac
switch on the control board. Triac current ratings and function below
16 amp Compressor on/off.
7 amp Defrost main heater on off
1 amp drain tray hearer on/off
1 amp air circulating fan on/off
If you would like to mail me direct with a paypal account address or
similar I would be very happy to provide a drink for you in return for
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