Hotpoint WD865 - dryer thermostat tripping

[^woody^]

I have diagnosed a tripped thermostat to the dryer, and replaced this, but it seems that the dryer heater is heating up, getting too hot and then tripping the stat.

The thermistor, element, dryer fan etc all seem fine.

Considering an airflow issue, I have looked elseware for air blockages to the condenser unit etc, but I can't see anywhere likely to be blocked.

What could be the cause of the heater element getting too hot? Its getting up to 120 degrees, and then the stat trips

 

[jj4091]

I am not familiar with that particular model, but o/h problems can only be caused by 2 problems, either poor air flow or heat control. You will have 2 thermostats one to control tempereture & the other(probably the one you have replaced) to detect o/h condition. They are usually near to each other & replaced in pairs.

 

[^woody^]

Thanks.

This one, as far as I can tell has only one thermostat, and a thermistor. The thermistor is working OK (ie it changes resistance to heat), but the thermostat trips.

What I cant understand is that the element is getting too hot and so tripping the stat. You say that one thermostat may control the element, but I cant see another one in circuit.

The only other thing before the element is a circuit board, so unless there is a controller on that board, I don't know why the element is getting too hot

 

[jj4091]

I am not 100% sure but I would guess that if you have a thermistor controlling the temp, rather then a thermostat, it is more likely to be the control pcb at fault.

 

[Sleepyhead]

Unfortunately there have been several modifications to these machines. Some have thermostats, some have thermistors and the heater boxes have been modified too. There are different elements so it's not easy to work this one out. A common problem if you have the plastic fan is the motor runs but the fan doesn't turn.