A dryer that tumbles happily while the clothes stay cold is one of the more confusing faults, because the machine looks like it is working. The explanation differs depending on whether yours is electric or gas.
Electric Dryers: Half the Power Can Be Missing
An electric dryer runs on a 240-volt supply made of two legs. The drum motor and the controls need only one of them; the heating element needs both. Lose one leg and you get exactly this symptom: a dryer that runs, lights up and tumbles, and never warms up.
That is why the first check is the breaker. An electric dryer normally sits on a double breaker. Switch it fully off and back on rather than glancing at it, because these can fail in a position that still looks on. If it trips again immediately, stop and have the circuit looked at rather than resetting it repeatedly.
Gas Dryers: Ignition
On a gas dryer, no heat usually means the burner is not lighting or not staying lit. Confirm the gas supply valve behind the machine is open and that other gas appliances in the house are working normally. Beyond that, the igniter, the gas valve coils and the flame sensor are involved, and gas components are not an owner repair under any circumstances. If you smell gas, do not operate the dryer or any switch; leave the house and call your gas utility from outside.
Both Types: Check the Vent
A restricted vent makes the dryer overheat, which trips a thermal fuse or a limit thermostat, and some of those are one-shot devices that leave you with a tumbling, non-heating dryer. Pull the machine out, disconnect the duct and check it and the wall outlet for packed lint and crushed sections. A flexible foil duct squashed behind the machine is a classic cause. Clearing the vent is essential anyway, because a replaced fuse on a blocked vent simply blows again.
What Needs a Technician
Heating elements, thermal fuses, thermostats, igniters and gas valves all sit inside the cabinet around high current or gas. Book a Whirlpool dryer repair visit and say whether the dryer is gas or electric and whether the vent has just been cleared, because both change what we bring.