Turn on my A/C and it just goes hummmm...

BE CAREFUL capacitors are used to store voltage that remains in the capacitor even with power removed. They can give a very nasty shock.

Use pliers with an insulated handle or gloves to pull the wire lugs from the capacitor.

To discharge a capacitor use a screwdriver with a plastic handle and use the shaft of the screwdriver to short (touch) the metal prongs on the capacitor to each other.

MEXICOWANDERER wrote:
I wonder about having to remove the top shield

Then climb down and start the machine

Climb back up then...

Then climb back down to shut it off.

A seized fans motor can be detected by (not) spinning the evaporator fan from below without playing the part of a spider monkey. And seized motor tun time is reduced to seconds not minutes. To each his own...

By careful observation the condition of fan motor bearings by hearing and by feel of roughness in the hand spun fan.

JMHO

While true, it take MORE effort to remove the inside plenums to access the Evap impellor. Some ducted you CANNOT access the Impellor from inside at all. So, the best result for a novice is to go on top and spin the fan blade of the condenser. While up there, you can also see if insect mud nests are the cause of the fan motor not turning. Doug

I wonder about having to remove the top shield

Then climb down and start the machine

Climb back up then...

Then climb back down to shut it off.

A seized fans motor can be detected by (not) spinning the evaporator fan from below without playing the part of a spider monkey. And seized motor tun time is reduced to seconds not minutes. To each his own...

By careful observation the condition of fan motor bearings by hearing and by feel of roughness in the hand spun fan.

JMHO

OP here. Thanks for all your suggestions. Right now we're getting a hearty rain (7" in two days) so I can't go out and get on top to follow your tips. I will when able...

marcsbigfoot20b27 wrote:

Charlie D. wrote:

down home wrote:

Just ahuuuuummmm the fan is not running and the compressor is not running. They are both on the same shaft.

Compressor is driven by the fan motor shaft????

Negative. The evap fan and the condenser fan are on the same shaft. Compressor is its own sealed unit.

I knew that. Just playing the devil's advocate

MEXICOWANDERER wrote:
Remove inside fan shroud. You have to do the following using a LOT of care and concentration...

With the TIP of your finger, spin the fan blades ONCE to help get it started. Does the fan then start? Wait for yes or no cold air output if fan starts. I've had three A/C fans fail and all three had burned motor winding segments as well as a blown capacitor. Be suspicious of replacing the cap then a slow windup on the fans.

BEFORE you do this. Have NO Power to the AC and go on top and spin the fan blade. IF it spins freely, then do the above. But if it drags or sticks, the fan motor is BAD. No amount of bearing lube will fix it. Doug

Remove inside fan shroud. You have to do the following using a LOT of care and concentration...

With the TIP of your finger, spin the fan blades ONCE to help get it started. Does the fan then start? Wait for yes or no cold air output if fan starts. I've had three A/C fans fail and all three had burned motor winding segments as well as a blown capacitor. Be suspicious of replacing the cap then a slow windup on the fans.

Damdifino wrote:

marcsbigfoot20b27 wrote:

Damdifino wrote:
I've been having A/C anomalies this summer, which I thought I'd fixed. First, it tripped the breaker, so I cleaned the coils, changed the circuit breaker, and it ran good for a couple of weeks. But now, I turn it on and it just hums, like it's struggling to start up. What should I look at?

Not enough info.

Does it hum and no air blows?
Does it hum and air does blow?

No air blowing.

At least now we know where to start. Most likely the fan run cap.

marcsbigfoot20b27 wrote:

Damdifino wrote:
I've been having A/C anomalies this summer, which I thought I'd fixed. First, it tripped the breaker, so I cleaned the coils, changed the circuit breaker, and it ran good for a couple of weeks. But now, I turn it on and it just hums, like it's struggling to start up. What should I look at?

Not enough info.

Does it hum and no air blows?
Does it hum and air does blow?

No air blowing.

lostbytes wrote:

ScottG wrote:
Exactly what mine did when the start cap died.

Yup. You not getting enough help from the capacitor. You'll need an soft start capacitor. It used to be you'll need an hard start capacitor but the newer soft are a little easier on the motor windings. Older ac usually needs some extra help because they wear out and need more wattage to get going. Just get one and hook it up piggy back to the original capacitor. Look up on YouTube/Google search about how to hook one up on an RV ac.
https://www.loveyourrv.com/installing-hard-start-capacitor-into-my-rv-air-conditioner/
Here's one on hard start.

If one of those original caps is bulging then it need to be replaced first. Then try ac. If problem not solved, then add soft start.

I have a MicroAir EasyStart installed. It's functioned perfectly for two months. Part of its "brain" includes a start capacitor. So far I've heard check the hard start capacitor, run capacitor, and fan motor. Fan turns easily, if that's any indication.