Hoover HNMF 2805a Fridge Too Cold

[RBZ5416]

This is a Hoover branded frost-free fridge/freezer. I can't get at the back easily for the model number (why can't they put labels inside?).

Edit - They do put labels inside but hide them with the saled draw! It's an HNMF 2805A so thread title amended.

It's approx eight years old & as far as I know, has a single compressor & thermostat control. The problem first started around 6 months ago following a evening of mains brown-outs, when the compressor seemed to be running continuously & the contents of the fridge were frozen the next day. I powered it down for a few minutes & all seemed OK. A couple of times since it's done similar & a quick power down has solved it.

But this seems to be becoming more frequent, especially since losing power for 12 hours during the storm of 28th October. I guessing this is an intermittent fault with the control PCB but would be grateful for any other suggestions.

I wouldn't have too many issues with replacing it if necessary other than it's a slimline (55cm) model that actually measures 54cm, & it only has millimetres of clearance. So getting a replacement that fits could prove tricky.

It appears that Hoover offer a fixed price repair for around £150 & would also be grateful for opinions as you whether that's likely to be good value. It's supposedly A rated but I don't know if that's good or bad by today's standards..

 

[drmaguire2107]

Some checks you can do, are you getting ice in the fridge compartment back wall does the fan in the freezer compartment spin freely when switched off ie unplugged,pull out all the drawers in the freezer fill a jug, small basin with hot water leave door open and switch on, the stat should sense the heat and energise the compressor and fan if the comp runs but the fan does not, then you need to check the fan itself are you confident enough to remove this and attach a fly lead to the motor terminals and provide it with voltage from a known source, if it spins when powered up when powered remotely then it is not getting a signal from its on board source be it a pcb or other control
DRM

 

[RBZ5416]

Firstly, thanks for taking the time to reply.

Yes, there is ice on the back wall of the fridge.

I've just pulled a couple of drawers & can feel a strong flow of cold air being blown through the vents at the back of the freezer, so I presume the fan is functioning OK.

I've just turned the 'stat up to max & back to one & the compressor has now stopped. Before turning it up it only stopped when set to zero, which even turns the light out so I guess is more of an "off".

It's just occurred to me that I can't recall having heard the creaks, cracks & groans of the defrost cycle for a while if that helps.

 

[RBZ5416]

Just played a bit more as the compressor had kicked back in.

The 'stat is number 0-4 plus a "super" setting at what would be 5. If I set it to the max & then back it off slowly, the compressor cuts fairly consistently at around 4.5. This seems to suggest that the 'stat is working & correctly sensing that the unit is very cold.

However, if I then back the 'stat right back to 1 the compressor kicks back in shortly after. I say shortly as in less than 30 minutes. Clearly the temp inside neither fridge nor freezer is dropping to that level in that timescale with the doors closed. Which suggests to me that something other than the 'stat is powering up the compressor, which in turn suggests a faulty control PCB?

 

[drmaguire2107]

Yep would seem like a signal issue, stat or pcb fairly common dilema niether I think will be cheap unless the stat is of the older type mech electric I am not sure of the model is the stat control on the facia or is it inside the fridge model number would help
DRM

 

[RBZ5416]

I think the stat's just mechanical. It's a dial that sits in the top panel between the two LEDs for "on" & "super". It's obscured when the door is closed but is external.

Edit - the temp control is linked to a pot on the main controller so not mechanical.

I'll have a hunt for the receipt later as it's just too much effort to try to wriggle it out of where it sits to access the model number.

I had a quick look around for a replacement yesterday & slimline's seem few & far between. Bosch would probably have been my preference but they don't do one. So the fixed price repair may be the only viable option, as long as they know what they're doing & don't try fixing it on the cheap first.[/i]

 

[RBZ5416]

Amazingly I found the receipt. It's a HNMF2805A from 2006, so not a bad guess. Control module looks to be £60 which isn't too bad. I can't see a stat listed separately so guess that's part of the module.

So, take a chance that £60 will fix it, assuming I can find an online resource to show me how to replace it, or the £130 fixed fee to save all the messing around. Hmmm...

Of course, the law of Sod dictates it's working fine today.

 

[drmaguire2107]

Qualtex,type in your model number, £30, PCB £16 for the defrost sensor
Dev

 

[RBZ5416]

Appreciate the help but that appears to be a trade only supplier, with no access for non-account holders.

Can't see it being an issue with the defrost sensor as presumably that just tells the heater when to turn on?

 

[drmaguire2107]

Sorry forgot that, buyspares, espares, are the most likely then
D

 

[RBZ5416]

Made a little more progress. Got access to the controller & there's no sign of any damage or bulging caps & no dry joints on the PCB.

Can anyone suggest some more diags to isolate the problem? On the spares list there is a "fridge sensor" with two wires & a "thermal fuse" with four. I'm reasonably competent with a multimeter & happy to knock up some shorting links if that will prove anything.

 

[maguire]

The fridge sensor is basically a thermistor, the resistance of which changes with temp, if you can get it out, then with a multimeter set on the lowest Ohms scale dip the end into some warm water and the reading will change, not by much but it should change
The themal fuse I think that may well be for the defrost, but not certain,
depends where the cables attached go one set may control the defrost heater and the other set might be the fan IE limiting the heater element and either supplyong the fan and/or holding it off during defrost
Dev

 

[RBZ5416]

Thanks Dev.

From what I've read the thermistor is "foamed in" (no idea where) & a bugger to change. I guess I should be able to see some change by placing a bowl of hot water in the fridge while measuring the resistance?

Edit - Just pulled it down again & it read around 6.8k initially & was dropping in value just with the door off. Went down a couple of hundred ohms in a matter of a minute or so. So I'm now leaning back towards the PCB again.

 

[maguire]

Looks like it, your getting there, if you can get the board out get a magnifying glass and check all the solder beads and look for blackening along the silver foil tracks
Dev

 

[RBZ5416]

Already done that & it looks completely clean. I've done the deed now so we'll see what happens...

I'll report back.