I am not sure on your model but, the transmission pump is probably or more then likely a charge pump for your main pump hooked to your crank shaft. It may have a seperate feed for like power steering from the transmission pump. The transmission pump would be open center.
One clue to a closed center is the accumulater.
I would suspect you are right that filter was removed on account of cold weather.
One clue to a closed center is the accumulater.
I would suspect you are right that filter was removed on account of cold weather.