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Re: Evaporator fan not working – Hotpoint Mistral F/F FF71S
Good news all… One less hotpoint on the scrap heap!
It seems to have been the yellow evaporator thermistor as the new one that arrived didn’t have anything like the temperature profile I posted above (it was just a curve like the green thermistor). Worthy of note for anyone else testing theirs in future 😉
I replaced both thermistors as a pair just to be safe. I also glued the defrost drip tray heater wires fully back onto the rear of the aluminium plate using Araldite that was good from -30 to +150C. The first difference I noticed was that the refrigerant pump didn’t come on straight away when I powered it up, but instead the drip tray heater went through a 10 minute defrost cycle. Evaporator fan reactivated at about -15C. Then I knew I was in business.
This F/F was about £600 when new. I realise they’ve dropped in price since, but with the added cost of having to dispose of the duff one this was well worth repairing for £40!
Thanks for your help folks! 8)
Re: Evaporator fan not working – Hotpoint Mistral F/F FF71S
Thanks footman2 – I forgot to mention that I did poke some flexible wire down both tubes and didn’t encounter anything. It hasn’t been operational for over a week now and that has included long periods where I’ve left it to defrost with no power. I think I’m in the right area judging by the numerous posts about thermistor trouble with this model – but accept new
thermistors may not cure it! Fingers crossed.Would still be grateful to hear from anyone who knows if the yellow thermistor is meant to have the temperature profile above? I can of course always compare with the new one when it arrives. 😆 😆
Re: Evaporator fan not working – Hotpoint Mistral F/F FF71S
OK well fortunately I don’t think anything sinister’s happened since I swapped the thermistors round, but it had me going for a bit yesterday!
I pulled them out so that they are dangling freely and I can now still get a -22 reading from the freezer as before. I suspect from the above readings that the yellow thermistor has gone though – and the perceived wisdom seems to be that you replace the green and yellow as a pair anyway and just cross fingers!
Fortunately found one website after about an hour of hunting that did have 1 green one left in stock. So looking forward to getting this fixed, hopefully, on Friday! In the meantime I’ll only put a few drops of glue to secure the drain heater wire back on, in case it’s the wrong sort of glue and I have to redo it later.
Grateful for your help and only sorry not to have been able to buy parts from your site. I suspect if this doesn’t work my patience will have gone and it’ll be a new freezer!
Re: Evaporator fan not working – Hotpoint Mistral F/F FF71S
Ah that makes sense – to stop the drain hole being blocked with ice…
I hope the glue between the wire and the aluminium plate isn’t conductive in any way – the wire seems to be fully sheathed in plastic from what I can see of it. So all I need is heat resistant glue and not some sort of conductive glue?
If so I’ve found some Araldite resistant from -30 to +150 in the man drawer that should do the trick?
As the freezer is now behaving more strangely than it did before (not cooling as far) I’m planning to re-check both thermistors to see if the green one is playing up as well.
kwatt – if I need a green thermistor is there a way of getting one any faster than the month delay in your parts store? Cheeky to ask I know, but a month without a fridge could be a bit of a bummer!
Thanks for taking the time to reply.
Re: Evaporator fan not working – Hotpoint Mistral F/F FF71S
Ah, good – that helps, thanks very much. That explains why I was getting a constant 2.9 kiloOhms reading from it (when unplugged) at whatever temperature!
However I assume it doesn’t do the bulk of the heating – there is a much larger diameter metal tube into which wires go and which is integrated around the evaporator coils in the normal fashion (in fact you can see the stains from it in the photo above).
This bigger heater still worked (ie. it was hot to the touch) even when the plate and wiring above was removed.
So is the above some sort of secondary heater? Should I try to glue the wires firmly back on to the metal film with some sort of heat resistant glue or is it really not important?
Thanks…
Re: Evaporator fan not working – Hotpoint Mistral F/F FF71S
A picture paints a thousand words… (and I’m sorry there were at least a thousand words above!!)
This is what I meant by the yellow resistor looking like it’s failed – or is it meant to have this temperature profile?
But before I go to the trouble of replacing it, can anyone help me identify what this wire loop does and whether it is critical that it is all glued securely to the back of the aluminium plate?
