This is tough. I've called a few and have gotten a few responses that have read "I don't really know you so I don't know what to write." Not surprising since it's been a few years and I only had you as a professor for 3 weeks.
I'll keep trying but it looks like I'm out for the count this round. Just a few schools ask for at least 1 science LOR so perhaps I'll try there and then try again next year.
Hmmm, these post-bacc classes for 2010-11 are expensive.
Don't call, that will creep them out! Nothing beats knocking politely on their door, greeting them with a friendly smile, warm handshake and act like you're happy to spend a few minutes with a former professor.
If they don't recognize, surely they can get clues from your body language right? Tell them you took their class, planning on med school, and needed a LOR from them if they're willing to write one for you.
I tell you this advice seriously and ask you to think about how much of a faux pas it is to do it over the phone. I also imagine you may have had a creepy/awkward voice because the phone call was definitely a bad idea.
If there are a couple science professors you haven't called yet, then go drive there in person. Nobody is going to tell you "yes" over the phone, especially when they're squirming in their seat and being made to feel uncomfortable. Do you see the viewpoint from their perspective? You are some worried student looking for help for his problem.
Since you probably ruined your best candidates, what you need to do now is own up to the fact you ruined your best candidates. The full list of teachers who are now to be considered your candidates are:
EVERY SCIENCE PROFESSOR YOU HAVE EVER HAD, WHO YOU HAVE NOT YET CALLED
Exhaust this list of candidates until you get one LOR that you need, and you do accurately
need a LOR from a science prof, given your facts proffered in this thread. If you exhaust this list (in person) then you should try one final chance at the professors who you have already called.
C'mon, you can do this! If you have any more questions, I've added this thread to my watch-list!
