Hotpoint 8596p Mistral plus, stuck in defrost?

[pete69]

I have a Hotpoint Mistral plus 8596p fridge freezer (frost free)
Having had an engineer out recently who changed 2 thermistor sensors (says on invoice) after it stopped working. It started again after his visit, but would not cool much. He returned and after looking for a while said the internal fan supply was missing and was a board fault, probably too expensive to replace.
Being an electronics background, I looked at the board and found the soft start thermistor to the fan was faulty, replaced it, and put the board back. It ran fine, cooled down, no problem all day. Then next morning found an ‘EE’ flashing and stuff melting. On power on/off showed +9 deg in freezer. The thing started working again, cooled down and ran all day. same thing happened the following day.
I checked by monitoring output triacs and found that it seems to be getting ‘stuck on’ the evaporator defrost cycle and after 20-30 mins has warmed up the freezer above zero. I have checked the board and can not see any obvious faults/dry joints also zapped all active components with freezer spray during this fault cycle.
Also the temperature reading in both compartments ‘lies’ when this fault is on, power on/off then reveals the much warmer real temp.
In desperation as a temp measure I have disconnected the heaters and by passed the supply to the compressor to give me emergency cooling. Can anyone help with this ‘defrost stuck’ problem please? also what code is EE?

Thanks. (pulling hair out…)

Peter

[Dave_Conway]

Re: Hotpoint 8596p Mistral plus, stuck in defrost?

EE is “defrost time out” error.

As long as all the heaters, thermostats and sensors in the freezer are OK the only route is a replacement control PCB I’m afraid, unless you can trace the component failure yourself as Hotpoint only supply the whole board.

Part number 2603400 at £114.40 inc VAT and delivery 🙁

Dave.

[pete69]

Many thanks Dave.
The machine is now permanently in Defrost mode, so I have had to apply the ‘bypass’ again.
Temperature shown for both compartments is wrong all the time now.
I am worried about throwing bad money after good, having spent over £100 with the engineer already.
I like the layout of this machine much better then the new alternatives and would gladly spend the £114 if I could be sure it would fix it.
However it seems likely I will go for a new one, dissapointed this only lasted 5 years, decent new ones seem very expensive considering the sum of the parts….
Thanks again for advice.

Peter.

[Penguin45]

Re: Hotpoint 8596p Mistral plus, stuck in defrost?

Before rushing off and spending oodles of cash, it may be worth contacting http://www.emwelec.co.uk or http://www.qer.biz for a quotation on a repaired exchange board. They will want the number from the board to identify it, and will still be considerably less than a brand new one.

Regards,
Penguin45.

[Simon46]

Re: Hotpoint 8596p Mistral plus, stuck in defrost?

Have you still got the old sensors and what was the original problem?

Simon.

[pete69]

Hi Simon
I guess the engineer took them.
First appearance of a fault was Compressor not running and contents defrosted. So I guess it could have been stuck in a defrost cycle back then…

Thanks Penguin45, I will check

Peter.

[pete69]

Hmmm
Something new guys, running in ‘bypass’ as for last few days
After switching off to briefly to stop evaporator freezing up. after normal time, freezer close to correct temp, but fridge staying at +14 or more (chceked with proper thermometer) , fan running..oh er..

Peter.

[Simon46]

Re: Hotpoint 8596p Mistral plus, stuck in defrost?

So with parts replaced same fault as before. Its the first thing i would have replaced as you can see by the threads if you search for mistral. Yours is unfortunate. But a nice fridge freezer all the same. I would agree wth Penguin 45 about trying the exchange board route.

S.

[pete69]

Simon, should the evaporator fan stop when the door is opened? cos it doesn’t.
The light goes out though…and the door is adjusted well.
It looks like 240v is just fed through the switch for the lamp, not sure how that can be used for signal levels to the LSI chip.
Fridge is still not cooling, maybe eveporator is frosted.

Peter.

[Simon46]

Re: Hotpoint 8596p Mistral plus, stuck in defrost?

Yes when fridge door is opened Evap fan will stop. If compressor is running is there cold in the freezer? (unless defrost heater is on!)
S.

[Simon46]

Re: Hotpoint 8596p Mistral plus, stuck in defrost?

The motorised fridge flap that lets the air in may also be closed. Not sure how it will run with compressor out of circuit as well. Please unplug before trying anything. But i know you knew that!

S.

[pete69]

Evap. fan DEFINATELY stays on when door opened, and, not sure, but always seem to remember it that way.
Evaporator heater and drain heater are disabled by me lifting a bit of track on pcb, because they are on all the time.
Compressor triac is shorted with a link
Both to get round this ‘permanent defrost problem’
So the pcb does not know’ I have disabled heaters and put compressor on.
Fridge now slowly cooling (thank God..)
Temp display still lying, unless power on/off, where it will tell the truth briefly.

Peter.

[Simon46]

Re: Hotpoint 8596p Mistral plus, stuck in defrost?

You seem to know your stuff. You also probably realise that the board is looking like it is faulty.

S.

[pete69]

OK, thanks for your help Simon. I’m an electronics technician by trade, although I rarely practice bench repairs it these days.
Didn’t know much about refrigeration until last week, but thanks to study and the help of benevolent people like yourself I am learning quickly.
Thanks for your patience.

Peter.

[Simon46]

Re: Hotpoint 8596p Mistral plus, stuck in defrost?

No problem. Hope you get it sorted.

S.

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