I have a code of 1 short blink and one long blink which is what I think is code 12 witch says: BLOWER ON AFTER POWER UP (115V or 24V) - Blower runs for 90 seconds, if unit is powered up during a call for heat (R-W closed).

What does this mean and can I fix it myself?? Help I'm COLD

Now it's been running okay but just went off again with a different code # 33?