Installed it all and charged it on Sunday. Coil is 2" above furnace, called a guy to braze pipes and check pressure. Said all was fine and good. Air was good and cold but it was clear some ductwork needed to be done so I am planning that, but I got plenty of return air and now I also got an inch of ice on my big copper line. Could duct restrictions on the output side of the system cause this much freezing? I still got a hot small line so I assume the freon is good, but I guess there is no way to tell without calling the service guy back out? Any input is appriciated.

PS, 4 ton 12 seer goodman split system with matched components.

I would recheck the pressures and if they are OK, perhaps speed up the fan or reduce the restriction in the duct work if you can.

Found one MAJOR problem, but no real solution short of a new furnace. It has a 3 ton blower in the furnace (Brand new 2005 Goodman) but my new system is 4 ton, oops. I was thinking of a new blower motor with like twice the rpms, but how well will this work? Any other options besides a new furnace?

Anyone know how much CFM airflow over the coil I need for 4 tons?

Most of the newer blowers have several speeds available, depending on which windings are connected. If you have the installation manual for the furnace, figure out how to use the highest speed, and see how it does. There may be a limit to the speeds available. There may or may not be room for a physically larger blower. Perhaps you could even add an auxiliary one in a duct. Most control are set up to use a faster blower speed for A/C than heating. Sorry I don't know more details.

So far I gathered it is about 400cfm per ton. As for aux blower, that is what I was thinking, I got a huge blower from an evap cooler, I was going to try it out, it moves about 4000 cfm so it may work OK.

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Originally Posted by Socrates

Installed it all and charged it on Sunday. Coil is 2" above furnace, called a guy to braze pipes and check pressure. Said all was fine and good. Air was good and cold but it was clear some ductwork needed to be done so I am planning that, but I got plenty of return air and now I also got an inch of ice on my big copper line. Could duct restrictions on the output side of the system cause this much freezing? I still got a hot small line so I assume the freon is good, but I guess there is no way to tell without calling the service guy back out? Any input is appriciated.

PS, 4 ton 12 seer goodman split system with matched components.

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You need more freon