Miele T8322 No Heat

[isodev]

My T8322 does not heat up. I have checked the front and rear NTC and they meter out to the correct resistance. I have not checked that they change with temp. The heater element is fine back to the pcb with 35 ohm on one circuit and 70 on the other.

When you power on the dryer it spins of about 1.5 mins then one of the relays clicks and 240v is applied to the heater coils. But relative to ground 240v is applied to all 3 wires (one common and the other two feeding the two coils). I am assuming that as there is no potential difference between the common and the other end of the coil then no current can flow so the relay card must be kaput. If you meter between common and one of the coils then you only get 2 or 3 volts.

After about 5 mins the beeper sounds and the cooling down light flashes continually.

I have read off the error code by pressing the start button 3 times and it repeats 1315-.

Does it sound like the pcb as I don't want to spen over £100 if it sounds like something else.

best
paul

 

[tonto33]

if vent is all clean think these ones have thermal fuse near rear exhaust duct

 

[DJB2]

Is the overheat stat ok? It sounds like it has tripped. You sound like you know a bit about the workings of the dryer but you didn't mention the stat. It's a metal disc close to heater (about 2cm with 2 terminals). If working should read near zero ohms. If tripped it'll be open circuit and heater won't run. Can be reset by throwing on the floor (hard). If you change the resistance to zero then you've been successful. This doesn't address the underlying cause though.

 

[isodev]

Hello and thanks for the response,

the electrical diagram does not show a thermal fuse on the outlet.

the thermal cut out is fine.

i have narrowed it down to the driver board. i disconnected the power connection, leaving the control logic from the main board connected.

Switched on the dryer, after a minute the relays were activated by the main board. Tested the relays had operated and found that the relay feeding from the neutral ( or 0v) had not closed. This meant that the 240v relay had closed and fed the heating coil with 240 v, but as the neutral line relay was o/c it left 240 v on all three of the heater wires.

i have checked online for the board and it is around £109. There is a service on ebay that repair them for £29 plus £5 carriage.

I studied the circuit diagram and discovered that the PCB is merely a dumb current switching device. So i looked up the relay and found that they are £4 on RS. Order one it will be here tomorrow.

Hopefully it will work when I have replaced the relay.

 

[isodev]

Have just changed the relay and bingo it works.

The only other problem is the residual moisture sensor has work away so that each rotation causes a noisy click as the plastic that hold the metal brushes hits the drum casing.

Does anybody know where to buy spares.

thanks
paul