I'm going to throw out another possibility that may, or may not, help. From my previous ownership of a Mazda, the only way the defroster would defrost was to have the A/C turned on (it made no difference whether the recirc button was activated or not). By turning the A/C on, the drier would start to work immediately, and clear the windows. It took the service manager a long time to convince me of that, but it worked like a charm ever after. Of course you can run the temp control ***** up to wherever, but the key is the drier absorbing the moisture.

If it works, let us know. Mine stays in the garage and has not been driven in climate weather...yet.