Home AC Not blowing

Ok HVAC experts, I have a problem with my home AC. forgive my novice terminology but here goes: suddenly today, I noticed there was no air/breeze coming out of my vents. First thing I did was change the filter, which was probably 2-4 weeks overdue (that’s normal for me). The filter change did no good. Next, I took the two front panels off and tried to observe any abnormalities. I saw none. For what its worth, the unit “sounds” normal. The rotor is spinning and generating a strong breeze. When I close the compartment however, I can easily manipulate the filter. Typically the filter cannot be moved because of the strong vacuum inside the compartment.

The unit is as old as the house, 1996.


Are you saying no air movement at all or just no cold air?

Have you tried several vents? Remember some are air intake vents and not exhaust. Its possible you ight have a blockage somewhere so figure out which air vents have air blowing from them and which dont.

How frequently do you have the unit serviced? I’m thinking the evaporator could be dirty.

By rotor do you mean the fan inside the evaporator housing (the inside unit) or the condenser fan,. (the outside unit)? If the condenser fan is running, but the evaporator fan is not, it’s a problem with the evaporator fan. The evaporator could also be dirty, preventing airflow even if the fan is running. It could also be clogged with frozen condensation, which would jibe with reduced airflow caused by a dirty filter.Try turning the system off for 1-2 hours then turning it back on. Either way, sounds like your due for a service and need to change your filtermmir often.

From what you describe it seems the Indoor Fan is not operating. You did not specify the type of system you have (Gas heat, Oil Heat, Heat Pump) but the indoor part of your setup contains the Indoor Fan Motor with its associated circuitry. The thermostat energizes the Fan in the Cool mode through the G terminal on your thermostat. The G terminal is connected to the Fan Relay and the fan relay energizes the fan motor. Check for 24 volts from G to common. Find the fan relay and check for voltage at the output terminal. The unit wiring diagram will identify the components, terminals, and wires you are looking for. The wiring diagram will be located on the inside of a panel or on the blower wheel housing. If it’s missing, Google the brand and model, you may get lucky.
If the relay is not passing voltage, it should be easy to get from any electrical or HVAC supplier

If the fan motor has voltage and it is not operating, one of two things has happened. Either the fan motor is dead or the start capacitor is dead. Here’s how you tell the difference. As mentioned above, check the fan relay and make sure you have full voltage to the motor. 115 or 230 depending on your system. Being very very careful, try spinning the fan wheel by hand. If the motor starts spinning and there are no odd noises, the motor run capacitor is probably bad. Get a new one.

If you need a capacitor, they are rated in microfarads @ Specified Voltage. Worry about the mircrofarads, not the voltage. Fan motors run 5 to 10 microfarads but may be different.

If the motor hums, just sits there, just sits there and heats up, shakes, vibrates, or gets really hot and has proper voltage, then it’s bad and needs to be replaced.

If you need a motor, you can get a direct replacement from the manufacturers’ rep or a dealer by model and serial number. Or you can get one from a motor supplier. (Grainger, Johnstone, Etc.) You will need to furnish the Horsepower, RPM., Voltage, Amp rating, mounting style, drive type, and motor shaft diameter. Typical ratings are from 1/6 to 3/4 HP, 115 or 230 VAC, 825 to 1800 RPM, belly band or cradle mount (some type of band around the motor shell or clamped down at the end bells), belt drive or direct drive, 1/2 or 5/8 diameter shaft. This covers 98% of applications, yours may differ.

Good luck.

If the fan is running, but no air out the vents, the “cold part” (evaporator) inside the house AC unit could be a frozen block of ice - preventing any air flow.

  1. Turn off AC for 24 hours.

  2. There is a water drain for the inside unit. Be sure it is not clogged.

  3. Replace air filter more often.

  4. If you live in a REALLY hot climate, get a window air conditioner, then you will have at least one cool room for now and will have a backup should your AC break again.

Plan on replacing it soon. Possibly even now – any major repairs are inadvisable. It’s not worth investing in a unit this old, when new ones are so much more energy efficient.

My 2¢: My 18-year-old unit went on the fritz a few weeks ago. I was prepared for the worst, but it turned out to be just a blown capacitor. While it wasn’t a “cheap” repair, spending $300 on replacing the capacitor versus about $4K to replace the unit was worthwhile in my opinion.

The really depends on what the problem is.
A frozen set of evap coils can be caused by something as ‘cheap’ as a dirty air filter (that the homeowner can fix, if they know what to look for) or even a refrigerant leak, which, if they’re ‘lucky’, and everything else is in good repair, hardly warrants replacing the entire system.

That’s a tough one, I always feel bad when it’s just a cap. If you know what you’re doing, it’s like a $30 part and probably two hours from the time you start poking around to the time the new one is in, including going and getting it*, but it’s still expensive if you have to call someone in. HVAC labor isn’t cheap. It’s one of those ‘well it cost $1 to turn the screw, and $299 to know which screw to turn’ things. Well, it’s more than that, but still, there’s a lot of education and experience priced into that labor charge.
*A few summers ago I was at my parents house and a shushed everyone and said 'do you hear that…(of course, no one did)…what is it…it’s…it’s a motor trying to start…don’t you hear that buzzing every few seconds…there’s a motor, somewhere, trying to start" When no one but me could here it, I told them to call me when they figured out what was broken and I could fix it. A day or two later they called to tell me their AC wasn’t working (they have two, so it took a while before they realized it). That bzzzzt…bzzzzt, is pretty recognizable as a motor with a bad cap. Luckily, their condenser used one cap for the compressor and fan (so I didn’t have to figure out which one was bad), I grabbed one from Grainger for $30, put it in and they were back up and running.