I have a Bosch fridge freezer, one of the KGU29 frost free series from
2000. The temperature in the freezer section is too high and there's
a frost buildup. I'm having problems matching up the generic
instructions in the repair faqs to my specific model.

What I don't get:

(1) Is the defrost timer likely to be on the PC board as I can't find
it anywhere? I am thinking it's unlikely the timer has broken if it's
electronic and everything else is working fine.

(2) There are five power inputs in the freezer: evaporator, fan
(working), thermostat (correct resistance), "Heater-defrost",
"Heater-element". Why are there two heaters? The resistance of one
is 310ohm and the other, 2400ohm, which looks high - probably going to
try replacing it first.

Anyone know how to get into service mode on these Bosch No Frosts?
Specifically, how to force defrost mode so I can do further tests?

Thanks in advance
Jonathan

"L Reid" wrote:

I was under the impression that 'frost free' only related to the fridge and
not the freezer? Looking forward to defrosting our 'frost-free' fridge
freezer this week before we move out!

Given the number of frost free problems turning up on uk.d-i-y
recently I think this is how they effectively work in practice!

I've defrosted the freezer now and temp has dropped right down, may
just be easier to continue doing this once a year. Bust the hairdryer
in the process though!

Jonathan

L Reid wrote:
"Jonathan" wrote in message
...
I have a Bosch fridge freezer, one of the KGU29 frost free series
from 2000. The temperature in the freezer section is too high and
there's a frost buildup. I'm having problems matching up the
generic
instructions in the repair faqs to my specific model.

What I don't get:

(1) Is the defrost timer likely to be on the PC board as I can't
find
it anywhere? I am thinking it's unlikely the timer has broken if
it's electronic and everything else is working fine.

(2) There are five power inputs in the freezer: evaporator, fan
(working), thermostat (correct resistance), "Heater-defrost",
"Heater-element". Why are there two heaters? The resistance of
one
is 310ohm and the other, 2400ohm, which looks high - probably going
to try replacing it first.

Anyone know how to get into service mode on these Bosch No Frosts?
Specifically, how to force defrost mode so I can do further tests?

Thanks in advance
Jonathan

I was under the impression that 'frost free' only related to the
fridge and not the freezer? Looking forward to defrosting our
'frost-
free' fridge freezer this week before we move out!

No, frost free means the freezer, a fan runs when the door opens, they
go for years without frosting up!

Don't know about the op's question though.

MrCheerful

(N. Thornton) wrote:

Jonathan wrote in message . ..
I have a Bosch fridge freezer, one of the KGU29 frost free series from
2000. The temperature in the freezer section is too high and there's
a frost buildup. I'm having problems matching up the generic
instructions in the repair faqs to my specific model.

(2) There are five power inputs in the freezer: evaporator, fan
(working), thermostat (correct resistance), "Heater-defrost",
"Heater-element". Why are there two heaters? The resistance of one
is 310ohm and the other, 2400ohm, which looks high - probably going to
try replacing it first.

not an effective repair strategy at all.

Either:
1. your air circulation fan has failed, which is most often the
problem,
2. or the defrost cycle timer has gone,
3. or defrost heater.
in that order.

This is the repair strategy I am following. As I said, it's not (1),
I'm thinking (2)'s unlikely, and as 2.4kOhm across a resistor for a
heater sounds very high I'm planning to replace it.

If anyone else knows any better, shout, there are at least thirty KGU
models all with similar workings.

What I don't get:

(1) Is the defrost timer likely to be on the PC board as I can't find
it anywhere?

What PCB?

Behind the readouts above the fridge

Defrost noramlly happends once per 24 hours. Its easier to just wait
for it.

I don't live in a studio flat and I do have things to do! And how can
I tell if it's trying to defrost if it's not working?

Jonathan wrote in message . ..
(N. Thornton) wrote:
Jonathan wrote in message . ..

Either:
1. your air circulation fan has failed, which is most often the
problem,
2. or the defrost cycle timer has gone,
3. or defrost heater.
in that order.

This is the repair strategy I am following. As I said, it's not (1),
I'm thinking (2)'s unlikely, and as 2.4kOhm across a resistor for a
heater sounds very high I'm planning to replace it.

If anyone else knows any better, shout, there are at least thirty KGU
models all with similar workings.

OK. One q tho: why's 2 unlikely?


Defrost noramlly happends once per 24 hours. Its easier to just wait
for it.

I don't live in a studio flat and I do have things to do! And how can
I tell if it's trying to defrost if it's not working?

If you wire a light bulb onto the defrost element and leave it powered
daytime only, it'll let you know when it switches to defrost. Its an
easy method, just dont leave it in such a way that someone could get
fried.

I would be concentrating on the defrost timer at this stage, and only
move on if you know thats working right.


Regards, NT

Jonathan wrote:

I have a Bosch fridge freezer, one of the KGU29 frost free series from
2000.

(2) There are five power inputs in the freezer: evaporator, fan
(working), thermostat (correct resistance), "Heater-defrost",
"Heater-element". Why are there two heaters? The resistance of one
is 310ohm and the other, 2400ohm, which looks high - probably going to
try replacing it first.

Probably the larger (wattage = lower resistance) one is in the
cooling coils to melt the accumulated ice, and the other is to
keep the water fluid as it makes its way out. That's how mine
(different make) is arranged.

Regards
Chris
--
Chris J Dixon Nottingham UK


Have dancing shoes, will ceilidh.

Jonathan wrote in message . ..
(N. Thornton) wrote:

Either:
1. your air circulation fan has failed, which is most often the
problem,
2. or the defrost cycle timer has gone,
3. or defrost heater.
in that order.

snip
OK. One q tho: why's 2 unlikely?

If the timer is on a PC board there is nothing mechanical to break,
and the rest of the circuit is working fine - correct me if I'm wrong?

Well, I wouldnt assume either of those things. Your defrost timer
cuold still be mech or tronic, and theyre usually mech. Secondly, even
if its tronic it would probably use a relay to do the switching, and
its the switching contacts that are the weakest link with mech timers.
So I'd still want to know about the timer myself.

If you wire a light bulb onto the defrost element and leave it powered
daytime only, it'll let you know when it switches to defrost. Its an
easy method, just dont leave it in such a way that someone could get
fried.

Good idea!

So now I've found not only is the timer working (at least sometimes),
so are both of the defrost elements. So I'm now thinking dodgy
connections or blocked drain. Plan is to use a bit of vaseline on the
connections and waggle around a bit with a pipe cleaner.

I wouldnt put that on heater element connections myself.


Regards, NT