How to troubleshoot Dryer not heating?

It could be a broken heating element:





However it might be a safety limit. Don't Assume you need an expensive element till you do some checking. In my neck of the woods electrical components ain't refundable. If you have air restrictions that would block airflow from the machine that could cause one of them limits to trip to avoid damaging anything. If those don't trip then thermal limits are in place on the ducting to melt and kill the dryer till remedy's can be done.



No heat could also be a control Klixon problem:


No heat could also be a dang burnt contact inside the timer
or that fancy logarithmic driven wonder of yours done took a dump.

It could be a bad breaker. Dryers motors here in the US operate on 120 volts or neutral and one hot leg. The heater needs 240 volts and 2 hot legs to get it's 5000 watts of heat a goin.Ya might think you have power to the machine when the breaker could be bad on the heat load side. It is IFFY when it starts to go out too.
How it works:
A heating coil or a gas flame is used to warm the clothes as they get tossed gently inside the drum. A blower mounted on the motor pulls heated air into the drum and out the exhaust. The element gets old and brittle with use and eventually needs replacement. That is what you check first. On gas dryers vibration and age will cause the ignitor to crumble and fail.

How it all goes down:
The drum temp control for cotton is 160f. A limit on the heater housing is 250f. If it fails another smaller limit is mounted on there which trips at 300f. If that drum temp exceeds 350f rapidly ,a duct fuse mounted on the blower housing opens and kills most dryers. On gas dryers the duct fuse will kill the gas assembly however, the dryer will still run. If all of those safety's are good, the timer could be the problem. The timer has a terminal on it that runs down to the heating element. If you suspect it is bad you can check it with a meter. That leg of the timer should have continuity with other terminals on the timer at different spots on the timer. Turning the timer and checking for continuity will give a clue. If you cannot get continuity with any other terminal on the timer at any position on the dial then you have a burned contact in the timer. If that turns out to be good, you would need to inspect the electrical outlet for proper power to the machine.

That is old school dryer what about them new fangled dryers? The ones with all of the fancy smancy controls that is supposed to save shocktricity? I have news for you the innards of these dryers for the most part is the same as above pictured. The only difference is fancy electronics. Today's modern wonders are subject to spike, lightning, and human error. What do I mean by human error? Tennis shoes in the dryer, not enough clothes, too many clothes, too much fabric softener. Today's dryers might look like the power laundry matt models that are built like tanks but they a severely lacking in stamina and strength. They are not the coin operated beast the salesman wants you to think they are, you cannot beat it up like one of these machines and expect it to perform. If I wanted a laundromat type appliance, I would order one for my home. If you got the kinda money they want for these new wonders then you ought to go all out and buy a laundromat model. LOL.These dryers are pretty, they have expensive electronics, but the basic innards are the same as they have always been. Most of these newer machines have moisture sensing bars on them. Right below the filter inside, these bars pick up the wetness from the clothes. As long as them clothes is wet, the dryer keeps a going. When them clothes get dry the sensors no longer detect moisture and send the dryer towards cool down and off. So what goes wrong on these? The dryer sheets and fabric softener builds up on those bars and moisture can no longer be detected. The dryer thinks the clothes are dry. It shuts down thinking all is propah. Get some Windex and clean the junk off the sensors and check.