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Hi folks,
As per the title, 5 y/o slim dishwasher, completes all cycles of all washes, does not heat. Generic heat pump 651956 replaced upon an almighty Google search, still the same. Basic continuity test of heating element didn’t suggest it was knackered when I took it out before ordering a the pump.
What constitutes the thermostat, is it built into the PCB? I was hoping it was a separate unit, but now I’m assuming something in the white box is kaput, anything common on these machines?
TIA
Re: Bosch sms40t32uk/01 not heating
A thermostat has to be able to measure the water temp so has to be in contact with the water. Don’t know for sure as tech info is sketchy with Bosch but the motor heater unit has 2 sensors on it and I am assuming they are the temperature sensors.
So if you changed the motor you have already changed the sensors. If you got a good reading on the heater why did you swop it?
Other possible fault is on the pcb there will be a relay that switches on the heater. That relay could be faulty or have a dry solder joint
Unless anyone else with more Bosch experience can think of anything elseDave
Re: Bosch sms40t32uk/01 not heating
I swapped the pump only on the basis that the thermostat appeared to be a part of it, and I wasn’t 100{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} on the resistances the entire circuit should have, but nothing jumped out as burnt and OC.
There were never ending posts and videos on the heater pump so I took a gamble since anything else would be more involved.
I will take it apart again and get a good look inside the box, just wanted some info in advance due to the faffing involved.
In hindsight I should have just taken the box to bits and looked inside. Been a busy few days though and what’s left of my brain is exhausted.
Re: Bosch sms40t32uk/01 not heating
Ok, so I’ve had it apart again. Continuity test between all wires to and from the heating element/thermostat are OK. Pulled the pcb out and on inspection, it looks as new as the day it was manufactured. No scorch marks, no busted caps, no blown chips, no cracked Solder, nothing. Aside from sticking it in the oven for a reflow, I’m out of ideas.
Locally there’s nothing else that can affect this. Regardless I did inspect all the other wires as far as reasonably practicable.
Gave the relays a good tapping to see if any were stuck, I have my suspicions about which one is the heating element relay.
Observations: upon powering the machine, the middle red wire to the element receives 125v, this does not change during a cycle and stays till the machine is switched off. Is this a nominal voltage or should it get the full 230 when signalled to?
It appears to be component failure on the pcb, but what?
I refuse to have my ass handed to me by a dishwasher!
Re: Bosch sms40t32uk/01 not heating
looked at the pert diags again to try to get any hints but no
it is doing a wash programme and not a rinse isn’t it
set a programme and listen for the soap draw to open you can then be certain it should be heating
my first though would be the heater relay failed. not had one go on these yet but there is always a first time
Dave
Re: Bosch sms40t32uk/01 not heating
Yep, it runs, opens the soap after a minute or so on quick, carries on, goes into the rinse cycle, I watch arm let the rinse aid out, drains, then turns off. All as normal, with no heating.
Running an eco cycle right now to double confirm.
Which one is the heater relay on the board?
Re: Bosch sms40t32uk/01 not heating
Ran the eco wash, same, draw opens after 14 mins, continues cycle, rinses, drains, turns off as normal.
Re: Bosch sms40t32uk/01 not heating
cant get that sort of info from Bosch
you can find the heater relay as it will have bigger connections and heavier wire than most connections to the board
Dave
Re: Bosch sms40t32uk/01 not heating
there is more info about the relay at the ‘stuck on one minute” thread. Mine didn’t show the burn marks on the boards but still had failed. I replaced that, cleaned out the matrix, reset and was good to go.
Most of the boards are similar i think. This is mine – the relay was the left hand one. OUr machine is the SRS45E42GB. I ordered mine from China – it’s cheap but takes a couple of weeks to arrive. You can probably check the specs and get en equivalent from Maplin. the board isn’t that compact so it’s quite easy to change.
Re: Bosch sms40t32uk/01 not heating
Final update, it’s fixed!
Desoldered the two largest relays and replaced em, good now. One of them I’m sure is functional, but I haven’t tested them yet, best replacing both for the sake of a couple quid.
Now anyone want a fully functional heating pump?
Hi, I wished I’d read this before I replaced my heat pump also although mine was registering open circuit across the two red wire oontacts, can’t seem to get the HF7FD0121ZPTF576 relays please?
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