[sputnik]

Re: hotpoint mistral plus 9596 fridge warm

mav12 wrote:cheers for that sputnik compressor is working ok now after leaving powered off for a while .
i am unclear on your fix about the resistors in parrallel i assume that would give 2..2 k this is what the evap thermister is showing now so i dont undersatand how it would work unless ive missed something
thanks

Heh!

That was exactly the reading I got with my evap thermistor when it was exhibiting its “fault condition”. It would eventually switch back to normal readings. I am 99{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} sure your problem is this thermistor!

Keep us posted on how you get on!

[sputnik]

Re: hotpoint mistral plus 9596 fridge warm

Hi,

3.4k sounds about right for kitchen temp in this weather.

However, it seems the evap thermistor can suffer from an intermittent “thermal fault” at temps at or around below zero.

See my post here viewtopic.php?f=33&t=64812

Don’t worry about the compressor / evap fan not coming on as expected. I had both these symptoms with mine. Fixed it for just over a quid. 😉

[sputnik]

Re: Hotpoint Mistral 8596

Sure enough it was the usual suspect, the evaporator thermistor! I found out that all the thermistors are of the same type, just different length leads and connectors, so decided to unplug the freezer and evap ones and test them side by side with my multimeter.

Apparently, the typical resistance readings should be approx:

Temp Ohms
-20C 26k
0C 8.9k
room temp 3k (I am assuming the scientific standard room temp of 22C)

I know there is another post on here by a service engineer that claims the resistance at room temp should be 31k but I am guessing this is a typo and he actually means 3.1k, which would go along with the above and observations of other posters who have ordered the proper Hotpoint thermistor and found it to read around 3k at room temp.

In my case, I found the evap thermistor would give good readings at typical temps used to measure it (ie. between freezing and room temp), but when it dropped below zero it switched backwards and jumped right down to 2k ohms (the equivalent of around 30C!!!). It stayed in this state right back up to room temp but would eventually fix itself.

Unfortunately I needed to get my freezer working quickly over the holiday season and couldn’t wait to order the official part from this site what with the post and all.

Now, from my observations of the “good” freezer thermistor, coupled with the above, I have determined that the official Hotpoint thermistor is actually an NTC 2.5K @25C with a Beta of approx. 3950

Unfortunately my local Maplins do not stock this, so I have made an equivalent “near as dammit” circuit by wiring 2 x 4.7K in parallel (Beta 3977). Maplin part number FX21X, cost 53p each.

I soldered the above to my old evap thermistor cable, sealed it in heatshrink and fitted it to the freezer. It has been running perfectly ever since my last post. Fridge down to any temp I set it to (0-6C), Freezer down to -22C. 🙂

[sputnik]

Re: Hotpoint Mistral 8596

Well, the E6 must exist as it came on again. Its just not documented on Hotpoints website. Besides, the EA was a red herring.

I defrosted, removed the panel in the freezer and the baffle in the fridge and low and behold the fan started working and the baffle solenoid operated (closed and opened) too.

Of course with the freezer panel off the fan was blowing into the freezer alone (as the ducting was no longer present) and so the fridge stayed at room temp while the freezer dropped to a displayed -20C.

I placed the panels back and the fridge temperature started to drop, and I could feel the cold air pumping into the fridge with the lamp switch shut, but it only reached around 8C, then the fan stopped working again and the fridge eventually went back to room temp.

I’ve since been playing with the thermistors and think I’ve found something but will report back later… 😉

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