McC,

1. I had similar problems with my '87 19016v. One of the techs on this site said the hot-air-all-the-time was a safety default so you would still be warm with a dry windshield if the unit failed.

2. After lots of research, i couldn't locate any troubleshooting for the unit. However, programma offers bench testing, core fees and have the best prices around. The "cheapest" way might be to take the box out yourself and send it to them for testing/possible replacement. Thats what happened to mine, it cost me 200 bucks and came with a 3 year warrentee.

cheers,
dan