".... will having a fan running caused a drop in the relative humidity level? No The molecules in air vibrate at a frequency based primarily on temperature. The warmer it is, the faster the molecules vibrate and the farther apart the molecules are, which is why gasses expand when they are warmed and contract when they are cooled. We can imagine this property at work if we imagine a given number of molecules of air trapped in a balloon. Stick the balloon in the fridge and it shrinks, yet the number of molecules of air remain the same, they just become closer together. Think of air as a sponge that can only hold just so much water. When molecules are warm and excited, there are larger spaces between the air molecules that can hold more water. When the air cools, it 'squeezes' the molecules together, which literally forces the water out - just like squeezing a wet sponge. Now to what happens in the winter: The cold air outside your house, because the molecules are vibrating slowly, is incapable of holding much water; but as that cold air finds its way into your home, it warms up, molecules become farther apart, and it suddenly becomes thirsty for water. Water evaporates quickly to fill the large, dry spaces with moisture. THEN, some of this moisture-laden air finds its way to the outside, through little openings in your home. This carries moisture OUT of the home. As this occurs, more cold air is coming in, picking up moisture ...... In a continuing process, it is: cold, dry air in, air warms and absorbs moisture, moist air moves to the outside, relative humidity falls dramatically. Simply moving the air with a fan won't have an impact on this process unless the air movement pressurizes air against an opening and it forces more moist air outside (which would cause more cold air to come in to replace it) than would normally occur. IF the moving air is passing over a moisture source, it will upset what is called the boundary layer of moist air that surrounds the moisture source and actually slows evaporation. Upsetting this boundary layer causes more rapid evaporation, which INCREASES humidity, so having a moisture source in front of the fan is a very good thing when trying to raise humidity. I employ this strategy in my basement grow room to help save on the cost of running humidifiers to keep humidity in the 55% range. Al

you can get rectangle window fans pretty cheaply at Walmart. They either have a reverse air flow switch, or you just turn them around. we use them in the evening to bring in the cool air. They work pretty well. You don't need a fancy one, about $20. (you can also blow the hot air OUT of one window and cool in thru another)

They're selling snake oil. There are so manys thing wrong with this proposal. First off, why do you feel you're not getting enough airflow? Is the room they used for their demo hard to heat or cool? If the existing 370 cfm is enough to keep that room comfortable, then there is no reason to pay money to increase the airflow. "More" is not always better. Your air handling system was designed to move air as an enclosed system. OF COURSE it's gonna move more air if you rig it to operate with the fan cover door opened. But again, more is not always better. I'll bet you could stand in that back room and *hear* the air rushing and whistling out of that vent after they took the blower door off. Your system should be set up to move the required amount of air as quietly as possible. You're also risking damage to the blower by making such a drastic change to the static pressure. The fan is designed to work against some amount of resistance. Lessen or remove that resistance and you could burn your fan motor out. A return in the basement is going to bring extra humidty and musty odors into your home. The air conditioning unit would have to work harder to remove the extra humidity. It could actually cost *more* money to operate. And if the unit was not capable of removing the extra humidity, you end up with damp air in your living quarters. This results in a cold, clammy feel that makes you feel uncomfortable. If you have some rooms that are hard to heat or cool, have a reputable HVAC company *calculate* how much air needs to go to each room. It's not a guessing game, and more is not always better. I noticed that you called the original installers and they blew you off. Forget them, they don't sound very professional. Try asking some of your neighbors for referrals, or check something like "craig's list". There has to be a reputable company in your area.

Yes, an ice block can stop air flow. A fan cant push air through a wall of ice. Have it looked at by a pro. There are multiple things that cause ice. And that is not a normal amount of ice btw. http://www.calldougs.com/article/what-causes-an-air-conditioner-to-ice-up