Why does my home Air Conditioner smell sweet?

The drain is clogged and there is water and crap fermenting in the bottom. I have a trane in the garage and it was also making a sweet nasty odor throught out the house. I turned the unit off in the house and I got a ladder and clean out the drain from the garage used Q-tips where the bleach did not get to and I put 1/2 cup of bleach in the drain. I let it sit for 10 minutes. Then I got the wet dry vac and went outside to where the drain is suppose to drain and I sucked out the drain. I repeated this step again in an hour. I changed all the filters and sprayed lysol in the return air. I turned the unit on again and I went to a motel for the night. Next morning the house was fresh and the garage was dry.