Indesit IDC75 condenser dryer not stopping

[notallbad]

I have an indesit IDC75 condenser tumble dryer and everything appears to be working ok
press start button and it starts spinning
does it reverse tumble at periodic intervals
heats up ok (heat switch toggles between high and low heat and working ok)
timer switch rotates as time passes by

However, there is one issue, it does not switch off when the timer goes back to "0', or 'off' if you like. Just keeps going. It will only stop if the door is opened, then closing the door requires the 'start' button to be pressed again to get it started.

I dont know the history of the machine so unsure if its a genuine fault with the timer switch, which I believe is the issue, or perhaps previous owner maybe changed the wiring to the timer switch.

Any ideas? thanks

No other electronics involved (so no relays) only the basic components:
water pump, flood switch and neon lamp
motor and run start cap
heating element with thermostats
door interlock bitron type switch
drum vent thermostat
heat hi/lo switch
momentary start button
timer switch

Photos of door switch and timer.

[notallbad]

I did think perhaps the control knob had been put on upside down or replaced with the wrong knob and that the timer function was 180 degrees out of sync but sadly not.

[stj]

i dont understand the "start button"
normally you just rotate the timer.
i wonder if the start button latches a contact that gets released by the timeswitch at the end of the cycle?

[petehall347]

does it have a cool down period at end of cycle ? if so it could be a heat sensor gone bad .

[notallbad]

Originally Posted by stj

i dont understand the "start button"
normally you just rotate the timer.
i wonder if the start button latches a contact that gets released by the timeswitch at the end of the cycle?

The start button is a momentary switch needed to start the cycle and the door switch possibly has a latch, its not a simple on/off switch with 2 wires, there are 3 wires.

[R_J]

either the switch in the timer is bad or more likely it is wired wrong, OR it's the wrong timer?
The manual for a IDC75UK has a C00269365 as the timer part number, it does not look the same

[notallbad]

Originally Posted by petehall347

does it have a cool down period at end of cycle ? if so it could be a heat sensor gone bad .

There is a 10 min cooling down period at the end, there are only 3 temp sensors, 2 are located on the heating element and the other on the front drum housing. All 3 are temp stats, on/off. Not NTC's!

[notallbad]

Originally Posted by R_J

either the switch in the timer is bad or more likely it is wired wrong

As the process appears to be working correctly. i.e drum turns and reverses, heater warms up, and the timer advances I would think it more likely faulty contact within the timer or wonder if the door lock is 'latched' on permanently? not sure how to test the door switch.

However, the heating element has been replaced and not professionally.

[petehall347]

Originally Posted by notallbad

There is a 10 min cooling down period at the end, there are only 3 temp sensors, 2 are located on the heating element and the other on the front drum housing. All 3 are temp stats, on/off. Not NTC's!

no idea how these work but i was thinking it might be similar to some diesel powered blow heaters . i know with those they wont turn off automatically if a certain temp sensor is bad . maybe check the drum one .

[notallbad]

all 3 stats have continuity.

If the door switch is a latched type I would have thought the dryer would start running as soon as the timer is set and no need to press the start button.

[notallbad]

So I.m guessing the way to go forward with this will be to bypass the start button and the door switch to eliminate them

[R_J]

Originally Posted by notallbad

So I.m guessing the way to go forward with this will be to bypass the start button and the door switch to eliminate them

This is not the way to go. When the timer comes to the end, the switch contacts need to open to stop the dryer. I suspect someone used the wrong timer or is using the wrong terminals on this installed timer

[petehall347]

some good tips here . and i might be onto something .. but i am often wrong .. anyway here goes ..
https://applianceexpresstx.com/dryer...clothing%20for.

[R_J]

I found this, it might explain some of the issues
The door interlock wire colors match the numbers

If you look at the eaton timer, my guess is that the switch between B1 and B3 is bypassed and the wire (pink/white) is connected direct to B9/10.

B11 and B12 must be ok if the motor is reversing
A11 is likely ok as well
I can't tell which terminals are used on the A side, It may be that there needs to be an additional jumper wire needed

[notallbad]

Timer connections

[R_J]

If you look at the diagram I posted, there is a switch between B1 & B3 that should close when the timer starts and opens when the timer ends. this turns off the heat, the motor and the timer itself. There must be one switch you can identify on your timer that switches when the timer is at 0 and when it is turned on.

This switch should be between the start relay/door switch pin 5 and mains neutral that supplies the rest of the timer switches.

Where does that wire pink/white wire from the door interlock pin5 go? is that it connected to A12 on the timer?

[stj]

thats what i'm thinking,
the run switch on the cam/timer has stuck contacts

[notallbad]

yh, I have come to the same conclusion as cant see how it would shut off otherwise. I felt that the wiring to the timer was as original due to the fact the wiring is so tight they couldnt have connected any other way really and just looked untouched, just intuition!
I have contemplated disassembling the timer but perhaps should wait until I have found a replacement first as at least its working at the moment and wont matter if things fly around the room like a firework display.The bbrass/copper dowels will need drilling out and replacing with nuts/bolts I guess.

As per photo A12 is mains 'L' via start button/door lock and B1 is mains 'N'.

[R_J]

I assume you have a meter, so check the switches without taking it apart

So the pink/white wire from the door interlock pin5 goes to A12 on the timer? correct?

It might be that there are switch contacts between A12 and A9 and they are stuck closed?

[R_J]

This diagram seems to match you configuration, and there is a switch between A9 and A12

On your timer I suspect it is not switching, (contacts may have arced closed or the plastic actuator is broken) Give it a couple lit taps in the off position to see if the contacts open.