Bosch frost free problems

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

Reply to
Jonathan
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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

Reply to
Jonathan

generic

'frost-

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

Reply to
MrCheerful

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.

Behind the readouts above the fridge

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?

Reply to
Jonathan

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

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

Reply to
N. Thornton

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

Reply to
Chris J Dixon

snip

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.

I wouldnt put that on heater element connections myself.

Regards, NT

Reply to
N. Thornton

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