We have replaced all heating elements, fuses, thermostats, etc... We have checked all wiring with the relay switch and still only blows cold air. We have the Kenmore 80 series. Can someone please help us?:(

Check the fusebox.

A dryer will turn with only 1 leg of the 220 line working. It won't heat, however.

If you have fuses, replace them both with the same size fuses.

If you have a circuit breaker, turn it off, and back on.

If this doesn't work, you may need an electrician, unless you're handy with a voltmeter, you can check you are getting 220 V at the outlet.

Stew

Diagnostic Guide Link
I found service tech diagnostic guides (PDF format) during an online search. This includes instructions on putting the dryer into test mode in order to check switches, etc. Here are the links:

Gas Dryer:
http://www.servicematters.com/docs/wiring/Tech%20Sheet%20-%203980053.pdf

Electric Dryer:
http://www.servicematters.com/docs/wiring/Tech%20Sheet%20-%203979705.pdf