So we bought an air conditioner that also has a dehumidfier in it to. My question is we have never before (last year) attached a drain hose to the back. This year I did and it pumps out water like crazy however in the book it says to only attach drain hose when using the dehumidifier. So am I overtaxing it by draining it I have no clue but hope you do?

Where was the water going that normally condensed on the cold side before? All air conditioners also dehumidify the air in the cooling process, and they all have water coming out in all but the driest climates. A dehumidifier just dumps the hot air in the same place as the cooler air. The air conditioner dumps it outside.

It is a floor model it has a drain plug I have no idea where the water went last year lol. It says in the instruction book there is a drain pan underneath but we have never had to drain it before. However the carpet was wet this year so I took the filters out to clean them and there was a brown paste type stuff and water so I assumed it neede to drain . So now I am confused

Yeah... it should have been drained before... that's mold and mildew from the water that collected before (it grew in the stagnant water). You must live in a real dry climate, you would have had a pool of water under it when it overflowed in most areas.

Nope very humid here now 40 to 90 % so do I leave the plug in or let it drain all the time Im running it in air conditioner mode

Drain it, or you will be inhaling mold as smoothy suggests. And take the bottom pan out and clean it.

Even window ACs get moldy in water in the tiny raised edge around the bottom. That's why they can get smelly so quickly.