Doesnt heat, or only works intermittently. - Frigidaire Electric Dryer

The intermittent nature rules out the thermal fuse (which is either burned out or not).
Take off the panel so you can watch the burner. If the ignitor comes on for a minute (you will see it glow), but then turns off with no gas igniting, the problem is probably the gas-valve solenoids.
If the ignitor heats up only once in a while (like after the dryer has been off for a while), but the gas consistently is released and the fire lights whenever the ignitor heats up, the problem is the thermistor (thermostat in the blower). The second thing is actually the easiest to fix, and cheapest. You my find that simply cleaning the thermistor probe will fix it. For my kenmore, the part has been updated from the original to limit the degree to which it gets fouled up with gunk. I can give you links to parts and/or instructions if you like.

Hi,

If you are having problems with your gas dryer not heating the most common problem is that the ignitor goes bad. Even though it glows sometimes it is still not working properly.

if you dryer is gas check out this gas no heat tip....

If you have an electric dryer, you can have many different things that can go wrong causing the dryer not to heat.

check out this electric no heat tip...

heatman101