Just thought I'd post here in the fond hope that it may save someone else some pain and suffering. I recently inherited a little-used and basic Hotpoint DF22 dishwasher from some friends who were re-working their kitchen. Looked tidy, and supposedly in good working order, so I had it all nicely plumbed in, only to discover that the timer got stuck at the start of the wash and rinse cycles, pretty much (but not always) every time. Nudging it past the sticking points each time got the job done, so to speak, but it wasn't exactly the carefree convenience I'd hoped for!
Finding service information for these machines on-line seems downright impossible - nothing out there at all so far as I could see, so had to surf the net for quite some while before concluding - correctly it turns out - that the problem was due to a faulty water thermostat. Is there really no service info in the public domain? Shame on you Hotpoint.
It turns out that what was happening is as follows:
Just after the start of each hot wash or rinse cycle, the mechanical timer in these units advances to the point where the timer motor gets its AC power ONLY through a normally-open (that is, open-when-cold) thermostat. This means that if the water is cold, the machine cycle doesn't advance; the machine waits - because the timer won't move on - until the water has warmed up before it allows the programme to proceed. All well and good provided that the water thermostat is in good order, is in contact with the door surface (of which more anon) and is properly wired into circuit.
In my machine's case, the water thermostat contact appeared to be only intermittently closed even when the thermostat is hot (50 deg C or more), so presumably current wasn't reaching the motor even after the water had heated up. Furthermore, the horrid plastic clip-in strip which presses the thermostat in place wasn't all that well fixed either (one end having popped out due to a broken plastic fitting at one end).
There are THREE thermostats in this machine, and no doubt many similar models. Two are affixed through the base of the machine and are thermally linked with the element - these are presumably used to control drying temperature and also - as a back-up, hence the sencond thermostat - to prevent overheating. Contrary to what some threads suggest, NEITHER of these is anything to do with the timer problem! Don't make the mistake I made in removing them to test them, only to discover that the twist-fix tab on the top isn't designed for multiple insertions and removals, and one broke off when I tried to straighten it to replace the otherwise perfectly-functioning thermostat!
The culprit in my case was the WATER thermostat which is a small button-type device fitted inside the door. The inner surface of the door of course "sees" the water spray, and the thermostat gets warmed by contact with the outside surface of the inner door. Replacing this part means removing the door cover only -- no need to turn the machine on its side, remove base or any of that stuff. Just take the six short countersunk screws out of the door sides (three on each side) and gently lift off the plastic door cover. (Be careful - some wires are captive to the cover but there's enough length to not need to remove anything if you're careful.)
Voila - the thermostat is in the middle, just under the opening for the door handle. In my machine the thermostat was clipped and pressed into place by a simple plastic push-fit strip - yuck! The press-fit fixing of this had cracked at one end, so the strip wasn't pressing the thermostat all that firmly against the door. I don't think this was the cause of my troubles, but it can't have helped. Removing this strip is a nerve racking business; yes, it IS a press fit and therefore has to be pried off. Some plastics - especially when aged - break with a gut-rending crack, don't they...
Anyway, fortunately managed to remove the original water thermostat without further damage, tested it using a multi-meter and kettle, and found it definitely suspect. Then a replacement was found on good old eBay for a few quid. (Incidentally the proper price for a button-style thermal switch like this is a less than a tenner. RS or Farnell stock similar ones, and if I hadn't had success on eBay I'd probably have tried to fit a generic replacement from one of these suppliers (50 deg C, normally-open contact). Thirty or forty quid from a "genuine spares" stockist = typical British rip-off.
As luck had it, the model of machine I have seems to have a spare thermostat position on the door - I assume two might be fitted in a more sophisticated version of the same machine, so as to offer multiple temperature options. So with a bit of slackening of some wires from the timer, I was able to fit the replacement in the adjacent position to the original, so making use of the other intact side of the plastic clip (it has three anchor points, fortunately the central one and the other end were OK).
Still awaiting a replacement for the needlessly-busted 85 deg C thermal cut-out in order to complete the job, and praying that the replaced cut-outs don't leak around their grommets. Incidentally, these cut-outs not only have a grommet to seal them but also have a square plastic "rain canopy" (about 3 inches square, with a round hole in the middle for the thermostat to fit through) - these are fitted between the thermostat and the underside of the machine, presumably to ensure that any seepage doesn't get on to the electrical terminals at the back. Needless to say - good ol' Hotpoint again - these don't appear in any spares listing I can see, and of course after a few years of heat the originals aren't in great shape. Might try to make replacements out of a sheet of silicone rubber, or perhaps just apply a smear of RTV (silicone sealant) around the thing before I fit it. Yes, I know that will make replacement more difficult.... ...does anyone know what these parts are called and where I might get "the real thing"?
Not exactly rocket science, but do hope this saves someone somewhere some work in future - it's the thread I was looking for but couldn't find! Good luck in your endeavours whatever they may be!
Mike
Finding service information for these machines on-line seems downright impossible - nothing out there at all so far as I could see, so had to surf the net for quite some while before concluding - correctly it turns out - that the problem was due to a faulty water thermostat. Is there really no service info in the public domain? Shame on you Hotpoint.
It turns out that what was happening is as follows:
Just after the start of each hot wash or rinse cycle, the mechanical timer in these units advances to the point where the timer motor gets its AC power ONLY through a normally-open (that is, open-when-cold) thermostat. This means that if the water is cold, the machine cycle doesn't advance; the machine waits - because the timer won't move on - until the water has warmed up before it allows the programme to proceed. All well and good provided that the water thermostat is in good order, is in contact with the door surface (of which more anon) and is properly wired into circuit.
In my machine's case, the water thermostat contact appeared to be only intermittently closed even when the thermostat is hot (50 deg C or more), so presumably current wasn't reaching the motor even after the water had heated up. Furthermore, the horrid plastic clip-in strip which presses the thermostat in place wasn't all that well fixed either (one end having popped out due to a broken plastic fitting at one end).
There are THREE thermostats in this machine, and no doubt many similar models. Two are affixed through the base of the machine and are thermally linked with the element - these are presumably used to control drying temperature and also - as a back-up, hence the sencond thermostat - to prevent overheating. Contrary to what some threads suggest, NEITHER of these is anything to do with the timer problem! Don't make the mistake I made in removing them to test them, only to discover that the twist-fix tab on the top isn't designed for multiple insertions and removals, and one broke off when I tried to straighten it to replace the otherwise perfectly-functioning thermostat!
The culprit in my case was the WATER thermostat which is a small button-type device fitted inside the door. The inner surface of the door of course "sees" the water spray, and the thermostat gets warmed by contact with the outside surface of the inner door. Replacing this part means removing the door cover only -- no need to turn the machine on its side, remove base or any of that stuff. Just take the six short countersunk screws out of the door sides (three on each side) and gently lift off the plastic door cover. (Be careful - some wires are captive to the cover but there's enough length to not need to remove anything if you're careful.)
Voila - the thermostat is in the middle, just under the opening for the door handle. In my machine the thermostat was clipped and pressed into place by a simple plastic push-fit strip - yuck! The press-fit fixing of this had cracked at one end, so the strip wasn't pressing the thermostat all that firmly against the door. I don't think this was the cause of my troubles, but it can't have helped. Removing this strip is a nerve racking business; yes, it IS a press fit and therefore has to be pried off. Some plastics - especially when aged - break with a gut-rending crack, don't they...
Anyway, fortunately managed to remove the original water thermostat without further damage, tested it using a multi-meter and kettle, and found it definitely suspect. Then a replacement was found on good old eBay for a few quid. (Incidentally the proper price for a button-style thermal switch like this is a less than a tenner. RS or Farnell stock similar ones, and if I hadn't had success on eBay I'd probably have tried to fit a generic replacement from one of these suppliers (50 deg C, normally-open contact). Thirty or forty quid from a "genuine spares" stockist = typical British rip-off.
As luck had it, the model of machine I have seems to have a spare thermostat position on the door - I assume two might be fitted in a more sophisticated version of the same machine, so as to offer multiple temperature options. So with a bit of slackening of some wires from the timer, I was able to fit the replacement in the adjacent position to the original, so making use of the other intact side of the plastic clip (it has three anchor points, fortunately the central one and the other end were OK).
Still awaiting a replacement for the needlessly-busted 85 deg C thermal cut-out in order to complete the job, and praying that the replaced cut-outs don't leak around their grommets. Incidentally, these cut-outs not only have a grommet to seal them but also have a square plastic "rain canopy" (about 3 inches square, with a round hole in the middle for the thermostat to fit through) - these are fitted between the thermostat and the underside of the machine, presumably to ensure that any seepage doesn't get on to the electrical terminals at the back. Needless to say - good ol' Hotpoint again - these don't appear in any spares listing I can see, and of course after a few years of heat the originals aren't in great shape. Might try to make replacements out of a sheet of silicone rubber, or perhaps just apply a smear of RTV (silicone sealant) around the thing before I fit it. Yes, I know that will make replacement more difficult.... ...does anyone know what these parts are called and where I might get "the real thing"?
Not exactly rocket science, but do hope this saves someone somewhere some work in future - it's the thread I was looking for but couldn't find! Good luck in your endeavours whatever they may be!
Mike
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