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keiths5n10 · May 14, 2013, 12:57 PM

Replaced blower motor last winter now with AC needed blower volume is weak! Direct drive blower & wired right! Can I tweak a fan limit switch? Honeywell incased type as I remember. Thanks Keith

mygirlsdad77 · May 14, 2013, 03:45 PM

The limit switch doesn't have anything to do with blower speed. And you are not to alter a limit switch in any way. I would start by checking/changing filter, then you may have to gain access to the bottom side of the evap coil and check to make sure it isn't plugged up. Also, if your unit is a high eff unit, you may want to remove the blower assembly and check the secondary heat exchanger (looks kind of like a car radiator) to make sure it isn't also plugged up. These things will dramatically lower cfms. Good luck and please let me know what you find.

keiths5n10 · May 15, 2013, 07:42 PM

First off thanks for your time & input!
This is an older unit Snyder, the filter was fine , cleaned A coil, not too bad.. seen a lot worse. I had replaced motor ( replacement a bit higher HP) this last winter, seemed to heat OK but now with ac season- It's just not pushing enough air, I pulled blower out & took to the elec. Shop I bought it, they said it was wired right! There must be something in the furnace elec. Workings I can tweak , if it wasn't direct drive I would change the pulley. About to give in to a HVAC tech.. Thanks Keith

mygirlsdad77 · May 16, 2013, 07:05 PM

Is this a multi speed motor? How many wires on the motor and what colors are the wires? If it is a multi speed motor, you may have a shot here. If a single speed motor, you won't get it to run any faster. Is the ac system "freezing up"? If not, is the air coming from the registers cold (take a reading with a thermometer).
Just one more question. Did the ac seem to work fine before the new motor was installed, or has this always been an issue? I hate to say it, but getting an onsite tech in to check out the system may be your best option. Just make sure to pick an experienced/reputable one. I wish you the best of luck with this.

Oh, one last thought. Look closely at the veins of the blower wheel. Believe it or not, if the veins get a buildup of dust of even a 16th of an inch, it can cause the cfm's to be cut by as much as 20 percent, or even more with more buildup. You can clean every vein one by one (very time consuming) or just remove the blower wheel from the squirel cage and pressure wash it. May or may not solve your problem.

Take care,

Lee.