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Good afternoon all,
I’m struggling to diagnose the above dishwasher fault.
On a wash cycle the heater is not being supplied voltage, thus not heating.
The heater itself gives a good Ohms reading, but I haven’t removed it to Megger it yet.
I have checked the wiring from the control module to the heater, which is fine, and thought the module was the culprit, even though there was no obvious damage to it.
However, having renewed the above the fault remains.
I wonder if the heater may be shorting, and has blown the new module too?
Any help much appreciated.
jontyRe: Bosch SGS45C12GB/16 Dishwasher Not Heating Problem
jontymox wrote:The heater itself gives a good Ohms reading, but I haven’t removed it to Megger it yet.
You don’t have to remove the heater in order to Megger it. If you tested its resistance in ohms why didn’t you check its earth resistance while you were at it?
jontymox wrote:I wonder if the heater may be shorting, and has blown the new module too?
I’ve not come across a control module that has been blown by the heater. Why did you change the control module incidentally, I’m curious to know?
And have you checked the thermostat/NTC on the heater unit.
Re: Bosch SGS45C12GB/16 Dishwasher Not Heating Problem
Hello again,
I can confirm that I tested the thermistor, which is fine.
I didn’t Megger the heater for two reasons; there is no voltage being supplied, and I’m unsure how to Megger the element without connecting one of the test leads to the element itself.
The related wires from the module to the heater are fine, so I deduced that there was a module fault.
jon
Re: Bosch SGS45C12GB/16 Dishwasher Not Heating Problem
jontymox wrote:I didn’t Megger the heater for two reasons; there is no voltage being supplied, and I’m unsure how to Megger the element without connecting one of the test leads to the element itself.
You’ve been in the trade at least 6 yrs and you don’t know how the Megger a heater?
I appreciate your honesty and might I therefore offer you some help in how to Megger anything, including heaters, explained in detail from the link below. Contained in that link is a .pdf file I created a few years back for those that needed that extra help in Basic Electrical Safety Testing……….. 😀
Re: Bosch SGS45C12GB/16 Dishwasher Not Heating Problem
Dear Martin,
I am looking for constructive assistance in this matter, which you may feel you are offering.
I am not seeking insults and/or mickey taking by an “Appliance Master.”
In fact, I certainly do know how to Megger test a heater.
I did not Megger test the heater largely due to the fact that there is no power being supplied to it!
This remains my problem in diagnosing this fault.
Kind regards,jon
p.s. it may make you feel superior in highlighting various sentences, and try to undermine other members, but in my view it does not.Re: Bosch SGS45C12GB/16 Dishwasher Not Heating Problem
So let’s recap on your problem.
You changed the control unit (though haven’t said for what reason as yet)
You measured the resistance of the heater yet didn’t Megger it. (If there were any problems with the heater the Megger test would highlight it)
Yet because you realised no power was going to the heater then testing its insulation potential was unnecessary. (Although you did ask us if the heater could have blown the Control unit).So now we know the connections between the two are in order and the control unit is new. So please allow me to ask : When you were live testing for power to the heater, did you have it set on ‘Quick Wash’ where the heater would be live the moment the water starts circulating or was it set on ‘Normal Wash’ where there would be no supply unless you waited 20 minutes into the cycle?
😀
Re: Bosch SGS45C12GB/16 Dishwasher Not Heating Problem
Good evening,
I have ascertained that the heater is fine, as is the related wiring to and from the control unit.
As damaged heater relays etc in the above are not unknown, I took the risk of ordering and renewing the module.
Alas, the problem remains.
Yes, I did carry out a live voltage test at the heater unit on the quick wash setting, and monitored it for at least ten minutes.
The customer had confirmed prior to my visit that the water was not heating, as I’d suggested this was the case for the reported fault.
As I was/am struggling with diagnosing this fault I did ask if the heater could short circuit, and damage the module… I was concerned it may have also damaged the new one, so yes, I should have carried out an insulation test on the heater first too.
Back to the drawing board.
jontyRe: Bosch SGS45C12GB/16 Dishwasher Not Heating Problem
There are 3 main reasons for no heat faults on these appliances. Low water level is the main culprit due to blocked pressure chamber/fill hose. Dry heater relay joint is second favourite followed by open circuit heater. If all of those are ok then you have to look at the ntc on the heater or maybe low water pressure due to a blocked circulating pump/broken impellor.
Re: Bosch SGS45C12GB/16 Dishwasher Not Heating Problem
Thank you nomadPaul,
The water level is fine, and I’ve ruled out the heater relay/joint after renewing the control module, and the NTC gives a good Ohms resistance reading.
I’ll investigate low water pressure, and hopefully identify the problem.
Kind regards,
jon
Re: Bosch SGS45C12GB/16 Dishwasher Not Heating Problem
Does this machine have a micro switch adjacent to the heater terminals? If so then this microswitch will only close when the wash pump creates sufficient water pressure, and thus switch on the heater. However if you say you have no voltage at all at the heater then in my experience it is always the relay on the control board that switches on the heater. Normally a dry joint is visible on the control board and can be repaired with a soldering iron provided you clean everything thoroughly at the joint. However this is not possible on some of the newer machines and only a new PCB will solve the problem. I hate to say this but there is a good chance you have been sent a duff PCB as I have had this happen to me. You might be able to get a second hand one on eBay just for testing purposes.
Good luck!
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