Well, it depends. How mechanically inclined are you? There is mucho information on how to debug the 124 climate control system in the archives here. Use the search function, a few good keywords, and settle in with a cup of java...

Frankly, it sounds like you have multiple failures. The hot air problem sounds like the climate control unit shutting down to protect itself. My first suggestion is to unplug the auxillary hot water pump (hint: it's under the washer fluid reservoir) and see what happens.

- JimY