Single fan chiller capable of cooling...?

I've got a 20x20x8' room that I currently use a small area of for a few reservoirs. Room generally stays on the cooler side as its concrete on all sides/floor.

I don't have the ability to vent this room but want a way to cool the room as I want to dry bud in there. Can a single fan chiller cool this room down to low 60's. I think ambient in there now is in the high 60's.

There no gear in this room except for a dehumidifier which puts out some heat.

Why not just use the dehum to do that job. Cooler temps won't help dry it. As long as the room stays nice n warm n dry you'll avoid any mold. A couple fans moving air never hurts to keep it moving over your buds.

I'm actually trying to cool the room down to prolong the drying time. I want it to dry minimum 14 days on the vine. I need to get in the real low 60's for both humidity and temp to achieve this. I run a sealed veg room upstairs and also want to use the drying room like somewhat of a lung room... chill the air in the drying room and draw the cool air into the veg room if needed and exhaust hot air into the lung/drying room.

I got a 70 pint dehum and the sucker puts off some hot air. It's welcomed on the first 2 days after chop, but once I get the initially dampness off of fresh chopped plants I really want to do everything I can to slow down the dry. Actually if I can maintain a 60/60 environment the entire room turns into one big mason jar. I can leave those plants hanging for a month or more and they will literally just cure on the vine.

Imo your asking for mold. What purpose does drying them slowly serve?
All you do is risk mold in the inner parts of the buds. Each to his own but for me drying fast is fine and preferred. If I want moisture in the weed I can add it back in later. But at least I know it's all free of mold.
If it's a cure your trying to do I don't think this is a wise way to do that. I could be wrong and hope it all works well for you though.
Nothing wrong with drying them on the vine as you said, just make sure they are dry inside. 60% humidity is too high for my liking.

You need to do a BTU calculation. It will depend on- the ambient room temperature and volume, the output of the dehumidifier and the cooling rate of the chiller. Does the chiller have a rating(it will change with water temp of course)? You can probably get the rating for the dehumidifier.
About 10,400 btu will drop your 20x20x8 room by 25f (from 85-60f) add 900 for the dehumidifier. 11,300 btu 0.9 ton of chilling.