The most common causes of a tumble dryer not heating up are either a faulty heating element, or a faulty stat (or TOC). A TOC is an acronym for thermal overload cutout and it’s essentially a heat activated fuse. Other common causes are faulty connections, and float switch or condenser sensor faults in condenser dryers.
What does a stat or TOC? look like and what do they do?
A TOC or thermostat should never be by-passed. They are there to stop serious overheating and a dryer could catch fire if run with one by-passed.
Where are the stats and TOCs?
Generally speaking if you can’t see one by removing a lid or back panel I’d advise not stripping it down – especially if a condenser dryer – as many dryers can be a right pain to strip and reassemble if you aren’t an engineer.
How to test a stat or TOC
They are tested with a simple continuity test meter. If there is no circuit from one tag to the other it’s generally because it’s failed.
Will replacing a TOC it fix the fault?
Not necessarily. Although these devices can fail for no apparent reason, they usually fail because of overheating due to another fault. In other words, a failed TOC could just be the symptom of an overheating fault in the same way as a normal fuse in a plug is the symptom of a different fault. If a TOC has gone you need to work out why..
Sometimes they can go for no apparent reason. On vented dryers a blocked or severely kinked vent hose can also cause overheating. Stopping a dryer mid-cycle can cause the overheating stats to fail on some dryers so don’t stop one mid-cycle (see don’t stop a dryer mid-cycle).
Some basic vented White Knight tumble dryers (and possibly others) have a red button on the back which can reset a cut out by pushing it in once it’s cooled down, (it should click when pressed if it has tripped). Again, if this keeps happening there must be something causing it, which needs proper investigation by an engineer.
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Faulty Heating element
Another cause for a dryer not heating is of course a faulty heating element. However, replacing an element in a dryer is often much more involved than most people would think.
Many tumble dryers would need completely taking to pieces. Some simple vented dryers though have heating elements that are more easily accessible by removing the back panel, and can be tested for continuity or checked for obvious breakage.
Some can just have a small compact heating element inside a metal housing, which slots in and out of the back easily – but most others have large heating elements inside, which aren’t accessible without stripping the dryer down.
A faulty element could be obvious by being physically broken or damaged, but if not, the only way to test one is with a continuity test meter to check that there is a complete circuit all the way through it.
To see what tumble dryer elements look like, and the variety of different types fitted, look at this Buy dryer elements and heaters
Micro switches and sensors
Condenser dryer float switches: If you have a condenser dryer it will be designed to cut off the heater via a float switch if the drawer or compartment holding the condensed water gets full. If the dryer stops heating check the compartment has been emptied of water – although most condenser dryers now should have some way of informing the user that the drawer needs emptying such as via a flashing light. It is possible for one of these float switches to go faulty, or stick, therefore triggering the warning when the chamber is empty preventing the heating element from switching on.
Summary of common causes of a tumble dryer not getting hot
- The heating elements can fail (open circuit) or have a faulty connection
- There are cut-outs and stats that can trip out or go open circuit (discussed at length above)
- Faulty connections and burned wires
- Condenser dryers can have float switches or sensors which cut the heater off if the water hasn’t been emptied out of the condenser drawer, check the water is emptied, these sensors and switches can also go faulty
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I agree it’s better to get an engineer in. Even if you found the toc’s you need to try and work out why they have tripped. There’s not a lot the average user can do on the DIY tumble dryer front in my opinion.
Hi I have a Lamona tumble drier which was not heating but still running. I have changed the heater , thermostat and PCB board yet it cuts out the heat when running, it seems to be when it reverses could it be the timer ?
I had a white knight vented dryer that is blowing cold air. I have pressed the red reset button and it did click…how long should I wait before trying it again?
Straight away Maggie. If it trips again shortly after it will be tripping because of a fault and needs looking at.
My indesit condenser dryer is only warm and not heating on full, any ideas what it could be please
I’ve seen cases where a dryer had 2 elements and one was working but the other not. That could explain getting warm but not hot Tracey. There are other potential causes though such as sensor faults.
Hi, would be grateful for advice. My White Knight c44a7w tumble dryer stopped heating. I have stripped the machine, tested the heating element ( by disconnecting all wires) – closed circuit. Tested both the thermostat and the safety sensor (with red button on it) – both are closed. To be absolutely sure I have short-circuitted both sensors but again the heater is not coming on. Visual inspection found no loose wires, broken or burnt parts , the machine is less than 18 months old.
The only suspicion i am left with is there is a control board with a couple of resistors, capacitor etc closer to the front panel – could it be that this board is not ‘sending’ power to the heater? I have even tested low/high button disconnecting one of the heaters – all seems to work.
Generally speaking, if the heater, stat and TOC are tested to be ok, where else should I look? Thank you
Hello Alan. White night tumble dryers always used to have a resettable stat with a big red button and it. Accessible from the back of the machine usually. The button reset when pressed. Does yours have this?
Andy, thanks for your response. The red button was the first thing i checked and it was not triggered. I have also tested the TOC and the stat – both are closed. Have short circuited them for a bit of time to be absolutely sure. Then tested the heater elements – both appear to be in order showing 44 ohm. So the only two options left are the pcb and the timer. But the motor is working fine so that makes me think the relay is ok as it is a single contact simple relay, so even the pcb could be ruled out. Any experience of timer contact failing the heater?
Hello Alan. Yes sorry about that but I needed to just double check the obvious which can occasionally get missed :-)
The switch on the timer can definitely fail. It is quite rare but I’ve definitely had that fault. The motor and the heating element will be supplied by separate switches. Essentially the dryer is a simple appliance.
With condenser dryers there is an extra possibility of a float switch or the switch that senses when the condensed water chamber is full that can cut the heat. But yours looks like a very basic dryer.
To test for this fault I would turn the dryer timer halfway round (don’t forget the last 10 minutes of the cycle cuts the heater out) then unplug the dryer and test with the continuity meter down the live on the plug to the heating element to see if it’s getting any power. The chances are it isn’t in your case because you appear to have eliminated the stats and the elements. If there is continuity there then you test from the element through all the stat’s and down to neutral. A fault on the neutral side can result in power running through all of the element and all of the stats but just not getting back down to neutral so everything is live but nothing works. Don’t work on the machine live.
If you engage the timer so that it’s definitely on a heating section and there is no continuity between the live on the plug and the heating element then you ideally need to trace the live wire back from the heating element to the timer or PCB. Make sure there are no connection faults or breaks in the wire. If there is proper continuity and the live heater wire all the way back to the PCB or timer then the only possible explanation for no power get into the element is that non-is been sent.