If there is no heat during drying cycle, it is usually either the heating element, or a thermal fuse.
See the following suggestions from repairclinic:
If your dryer doesn't heat, check these:
Heating elementThermal fuseWiring
Heating element
Often
a dryer heating element burns out, but doesn't trip the circuit breaker
or blow a fuse. The heating element is simply a long coil of special
wire. You can check it for continuity with an ohm meter. No continuity
means the element is bad and you need to replace it--electric heating
elements aren't repairable.
Thermal fuse
On
many dryers, there's a thermal fuse mounted to the exhaust duct inside
the back cover panel. The fuse--which is about an inch long--is usually
embedded in black resin and mounted in a white plastic housing. If the
fuse has blown, you need to replace it. (You can't re-set it.)
Wiring
A
common problem is for the main wiring connection from the house, at the
dryer, to burn and break its connection. Because the dryer can still
tumble with partial power, the connection may be only partially
defective. You may need to replace both the power cord to the dryer and
the terminal block inside the dryer that the wire is attached to.