Capacitors! Yikes!

[hvacmike85]

Yeah and it's gonna heat up a whole lot faster when the voltage drops. Probably have compounding problems.

Good point though, is like to be there with a meter when one blew, we would all prob learn somethin

[hvacmike85]

I read somewhere that if you gang up caps if you don't have the right size to get the correct capacitance then you are actually better off because of more surface area to dissipate the heat.
But there never seems to be enough room in the smaller condensers.

Good theory, i worry if one dies the unit runs starving for that juice and ends up burning up instead of just quitting when its blown (single cap)

[ICanHas]

Where do you get the idea that voltage drops are causing it? Do you guys have any data showing higher failure rate at apartment complexes and light commercial than houses?

They get 208Y/120v service and run the compressor on 208v.
There are 200v motors meant for 208v service and 230v motors for 240v, but most are 208/230 approved, so apartment complex condensing units are running dual rated compressors at 208v nominal.

Single houses get 120/240 and run on 240v.

Condensing units are almost always rated 208-230 and its a sure bet that 240v service seldom drop below 208v.

[hurtinhvac]

Swelled caps sometimes three calls in a row. More and more CF motors and now blower caps as well (two this week). Heat and continued use. I am only carrying 440 where possible. The left hand side of my truck quickly becomes a graveyard of swollen, leaking caps and I like to point them out to the hovering HO who just got hit with a $ bill for trip and a new cap.

It is to the point, on that last call of the day (the one where they say "the outside fan is not spinning and pumping cold air"), I'll walk up and hold my breath as I grab my long skinny screw driver and give the fan blade a twirl. And let out a sigh of relief if it spins easy. Bad cap - home only a couple hours late.

We have not had a stretch like this in this area since the 30's.

BTW..you guys been seeing really...really high pressures while still maintaining decent SH and SC readings? I know very well the pressure temp. relationship - but...wow.

Interesting cooling season for a newer tech, if nothing else.

[anthonyac1]

i also stock only 440V last time i went to the motor supply house. after i was leaving i asked about capacitors they showed me run caps that are made in japan
it looks just like a start cap black and in a plastic housing with a tab to put a screw in it to hold it to the housing upon installation, they stressed how much better but wondering if anyone tried them out yet.

[fs1]

Here is a nice link for the guys who haven't been to/or its been a long time since schooling. About 7 minutes in is very helpful....Most of your questions are answered in this video......ENJOY

[midhvac]

Just hit me that during this heat wave, I've seen no failures of capacitors that are mounted through holes in the bottom of the electrical compartment, like on the Rheem & some other units i.e. the ones where the entire outer perimeter of the cap is down in the condenser area, where the condenser fan is pulling air across it.
Seems like more evidence that the heat is the culprit. It would also explain why it doesn't help to replace the combo ones with separate comp. & fan caps or parallel wire the caps. They'll still hit the same temp in the same location.

[mark beiser]

Good theory, i worry if one dies the unit runs starving for that juice and ends up burning up instead of just quitting when its blown (single cap)

I imagine the compressor would be a lot better off with an under value capacitor than, for instance, a compressor that has a bad run cap, but starts and runs anyway because it has a start kit.

Just hit me that during this heat wave, I've seen no failures of capacitors that are mounted through holes in the bottom of the electrical compartment, like on the Rheem & some other units i.e. the ones where the entire outer perimeter of the cap is down in the condenser area, where the condenser fan is pulling air across it.

While I believe this point has merit, I still find plenty of Rheem/Ruud units with bad caps.
It is actually quite annoying having them mounted like that, because it can be very difficult to get the capacitor out if it swells at all when it fails.
i've had to poke holes in capacitors to relieve the pressure so I could get them out of the mounting hole.

[Glennhvac]

Just hit me that during this heat wave, I've seen no failures of capacitors that are mounted through holes in the bottom of the electrical compartment, like on the Rheem & some other units i.e. the ones where the entire outer perimeter of the cap is down in the condenser area, where the condenser fan is pulling air across it.
Seems like more evidence that the heat is the culprit. It would also explain why it doesn't help to replace the combo ones with separate comp. & fan caps or parallel wire the caps. They'll still hit the same temp in the same location.

I think that may just be a matter of statistics as Rheem/Ruud are one of the very few units that I run across that mount them that way. If anything I would bet the ambient temp is higher in that location simply due to the fact you are adding heat from air pulled across the condensor.

[mike dixon]

hey hurtin,, i see you are in st louis, $ for a cap change out, my god, you must work for jerry kelly lol

[Glennhvac]

Here is a nice link for the guys who haven't been to/or its been a long time since schooling. About 7 minutes in is very helpful....Most of your questions are answered in this video......ENJOY

Great link! Thanks. I can see why those old caps that were bigger than house bricks lasted so long. Besides the fact that they were probably ten times the quality they also had far more surface area to shed heat. Might be why some of those 30+ year old Lennox units with three and four caps still have the originals.

[hurtinhvac]

hey hurtin,, i see you are in st louis, $ for a cap change out, my god, you must work for jerry kelly lol

No...I haven't screwed up that bad yet - but point taken.

I have to admit to wincing now and again as I fill out the bill.

"Our price book is based on a national average...blah...blah...blah...."

"It cost a fortune to have them on the truck and installed within a few hours...yada...yada...yada..."

'Bout how much do you get for a trip and...say a 40/5 440?

[timebuilder]

You guys realize that this is a open forum, right?