Fan is turning on air conditioner but no air movement

Question

A few weeks ago I changed the outside unit's starting capacitor and that got the fan on that unit to rotate and the air conditioning on the enclosed back porch started working.

Today I came home and the main part of the house was hot. I turned down the thermostat in that zone but I still didn't feel any air blowing out of the registers. I changed all the air filters but still didn't feel any suction at the filter housing or any air coming out of the register.

I had my wife turn on the air conditioning via the thermostat while I was downstairs listening at the inside unit. I heard a sound like a refrigerator or dehumidifier kicking in and then a few seconds later I heard the sound of a fan starting up.

I removed the cover over the fan and taped the safety switch and turned on the air conditioning and I can definitely see the squirrel cage fan running and it looks and sounds normal.

For what it's worth the fan on the outside unit for this zone seems to be spinning normally as well.

How on earth can I not feel any air coming out of the registers or feel any suction at the air return? The only thing I can figure out is that the fan seems to be running normally, but is actually at a lower speed than normal. It sure looks normal. I don't see any gaping holes in the ductwork or anything.

I've changed the fan on my furnace in a previous house a few years ago, so I'm somewhat familiar with what they should sound like. The inside unit is a York affinity 9.V series

Here's a video of the fan running.

Answer 1

That video sure looks like rotation is backwards [it should be spinning clockwise as seen based on the scroll/label], but... could be strobe effect from camera rate? I can't think of how to switch rotation on an ac motor run by a simple contactor but by rewiring the motor leads - racoons aren't that clever [yet]. If it's fooling us, then look at ductwork: if you have flex duct which had an internal collapse, air flow could be blocked. Another option is your dampers used to balance distribution out of the air handler came loose and the butterfly is closed. If it is in fact running backwards, then does it use some solid state controller [pwm, or other variable speed type drive]? That would be the culprit.

Answer 2

If your main Squirrel cage blower for your vents is spinning, ( blowing air ) you should feel air.

Answer 3

In my case the fan started working normally after I turned off my AC for 24 hours or so. My problem was that my coolant was leaking out, causing my coils to ice up. The iced up coils blocked air from flowing through the system. Hence my fan was spinning but no air was recirculating.