A/C Issue

[Ranger_Smith]

Have noticed that I have 1 of my 3 AC units that the compressor only has been shutting off after about 15 minutes blower fan and upper fan outside will stay on.. It will then come back on in about 10 minutes or so and keep doing that cycle. Took off top cover and cooling coil inside is clean. Unit was not freezing up. Re sealed unit as I thought air might be getting in. Possible thermal shut down of compressor??? Dealer is aware of problem with the unit.

[DFord]

Bulging is the SURE sign of failure when it comes to all capacitors. No need to replace them all. You could have purchased a meter and saved some money.

I've personally seen scam artists dressed in HVAC uniforms find "bad" capacitors on residential furnace/air conditioners while performing seasonal checks of the equipment - in this case the equipment was under an inexpensive service contract and the outrageous price to replace the capacitor was all money in the pocket for them. Beware!

If the label on the capacitor says it's supposed to be rated at 7.5mfd and the tester says it's only good for 6.5mfd or 8mfd, don't sweat it. The important thing is can it start the motor or not. 10% tolerance is acceptable. In the case of a bulged capacitor, I'm sure it wouldn't come close to its rating on the label if it registered anything at all.

As I said earlier, in my world, start kits are must for RV air conditioners. They'll start the compressor in less than the blink of an eye before the power pedestal breaker knows what happened.

[Ranger_Smith]

Replaced the 40uf capacitor and all seems to be well. The top of the capacitor was starting to bulge on the bad AC unit. Got 3 from my AC guy for $50 and changed them in all of the AC units. Was original from 2010

[DFord]

I've never seen or even heard of "shared" start capacitors. You must be referring to run capacitors where are often shared. It that is all there is there must not be any start capacitor for the compressor. Start capacitors are never used for the fan motor because the sudden start would damage the fan blades which should come up to speed slowly compared to the compressor. If it were me, I'd leave the "softstart kit" on the system. All RV air conditioners used to come standard with start kits (a start capacitor and relay) but from what I'm hearing, mfgs have stopped doing that - bad idea in my book.

The only way to know if a capacitor is "weak" is to have it tested with a meter - about $15 and up on Amazon: https://www.amazon.com/s?k=capacitor+tester+meter&crid=X01HAKMEMSRY&sprefix=capacitor+test%2Caps%2C2...

[wa8yxm]

chuckftboy wrote:
A weak run capacitor could cause the amps to go up and open the thermal switch (klixon) when it cools and resets the compressor would start again. Just a thought.

The unit can have up to 4 caps (RUN and Start. Times Blower and Compressor)

I have an advent air (just start caps no run) and the compressor half of the start cap is "Weak" the result is when I turn it on it runs fine but when the compressor attempts to restart after it cycles it goes CLICK at the breaker and I then wait and reset and it does it all again.

I finally installed the softstart kit (Diagnostic in this case) and it's just comleted 27 hours witout clicking the breaker off.

New cap goes in next week.

[Ranger_Smith]

Fans are running fine. Checked evaporator and condenser coils. All are clean. Did a search and several threads came up about weak capacitor. I have 2 ordered and they will be here today from my AC guy that handles the AC in our rental units. He said that is probably the problem.

I'll let everyone know what I find.

[DFord]

It sounds like the internal thermal overload inside the compressor. BTW: The inside and outside fans are on either end of a double shaft motor. If one's turning, the other end better be!

If it was mine, I'd turn it off until it was fixed.

[chuckftboy]

A weak run capacitor could cause the amps to go up and open the thermal switch (klixon) when it cools and resets the compressor would start again. Just a thought.

[wa8yxm]

Did you check the condenser coils as well. they get clogged with all sorts of debris since they are not filtered.

[Lwiddis]

“Dealer is aware of problem with the unit.“

Hopefully your do it yourself repair attempt won’t void the warranty.