AC Start Capacitor

[chocolatelab]

uggg

Its hot and the ac went sideways yesterday.

Happened to catch an AV service guy in the neighborhood.

Start Capacitor bad.

Replaced said start capacitor.

Service guy recommended hard start in addition.

I turned this option down thinking the first lasted at least 8 years why do I need it.

Welp.

24 hours later the new capacitor just took a crap.

What causes capacitors to go bad?

[Baz]

Not an expert but you may want to check out your compressor.

Mine took a dump earlier this year and I replaced the whole condenser unit.

Also, I installed a small 110v window unit years ago that I can use for "emergencies". When an AC issue comes up with my central air....it buys me some time to figure out a game plan or do diagnostics.

There's a lot of info on You Tube plus some really great folks here who know their stuff and can help.

Good luck!

[chocolatelab]

i suspect thats where I am heading.

Old system. Gonna have to swap all kinds of stuff out.

[chocolatelab]

i suspect thats where I am heading.

[campbellcj]

I went through something similar earlier this summer. Our tech said the motors get harder to start when they get old, and eventually they won't start at all. In our case they replaced the motor and credited us back for the new cap as they realized the old one may have been OK and the motor was the culprit. So far so good.

[chocolatelab]

Interesting. That makes sense.

[1990C4S]

I found a nice compressor in the garbage a few years back. Start capacitor was toast. $5 and a few years later it still runs like new.

I have read that the capacitors are all made in China and are supercheap. I suspect it is true, as the failing capacitor syndrome is new phenomenon. Ten or twenty years ago it was unheard of.

I would look around for a very old capacitor on an old compressor. Odds are it will last a lot longer than a new one.

Maybe Billybek will chime in....

[red-beard]

The capacitor in an AC unit is a RUN capacitor. Most do not have start capacitors. You definitely want one. Only get the 5-2-1, aka a 3 wire start capacitor.

[javadog]

Don't use one that was made in China. Try to find one that was made in Mexico, if you can't find a US product. I haven't used a Chinese cap that lasted any time at all.

JR

[stomachmonkey]

Originally Posted by javadog

Don't use one that was made in China. Try to find one that was made in Mexico, if you can't find a US product. I haven't used a Chinese cap that lasted any time at all.

JR

My AC guy confirms that.

Says you'll spend 3 times as much for the cheap Chinese caps because you keep replacing them.

He only buys and uses US made.

[billybek]

Replace the starting relay when you replace the start capacitor.
Usually the capacitors last a very long time but can on occasion go bad. Quite often the starting relay is the problem.
There are two types. Current relay where the start capacitor is connected to a normally closed switch.
This gives the motor a kick in the butt to get it rolling. When there is current draw through the windings the switch opens and the start capacitor is out of the circuit.
The second is a potential relay. These are position sensitive and must be mounted in the direction indicated. These relays are normally open and close with the high starting potential between start and common to put the start capacitor in the circuit. When the compressor amperage drops to its RLA from its starting current the start capacitor is taken out of the circuit.
When I did do some work in the residential side of HVAC I would always replace the starting gear with the factory relay and capacitor.
With compressor on the way out I would try one of the kits just for the heck of it. Sometimes they work and sometimes the compressor is too far gone. YMMV

[chocolatelab]

AC guy came back out and replaced capacitor.

Reported rest of the system is operating properly and that the one he put in was bad. Chinese made he said.

My suspicion is he put a used one he had in the truck in and crossed his fingers it was good.

Anyway. 1 year warranty is nice to have.

The reality is I really need to look at replacing all 3 units. Almost 20 years old.

ill save that for another day.

[ShakinJoe]

Originally Posted by red-beard

The capacitor in an AC unit is a RUN capacitor. Most do not have start capacitors. You definitely want one. Only get the 5-2-1, aka a 3 wire start capacitor.

This is the correct answer and the 5-2-1 is a great product and easy to install. The capacitors from China are horribly made and should be banned from entering this country.