Most problems with tumble dryers not heating up is the Thermostats, they act as switches cutting off/on power to the heater elements. Most dryers have two of these components, you can test it with a circuit tester, but make sure the power if off and you disconnect the terminals on the thermos. Even if they seem to be okay they may be ceased and giving a false reading, my advise is to changed them in any case. Help this helps. Hotpoint engineer.
John Bowley, June 2004