HVAC question again (capacitors this time)

Rich

Rich

Asshole at large
Joined
Mar 17, 2005
Location
Central PA
So the cap blew in our downstairs one yesterday. Went to the only supply store in Raleigh that's open weekends (Thank goodness it is open on Saturday at all!)

Old cap was a 370v, 35uf + 5uf. (1.5 ton unit)

The closest one they had was a 370v 40uf + 5uf.

I bought it, the counter guy said "it's not good for the unit, but it'll work"

My question is - how bad is it for the unit?
 
only difference is when it fires it will release 5 micro farrads more.

Im no HVAC guy but on any electric motor I would rather give it a touch too much juice than a touch low.

Certainly wont hurt between now and monday
 
SkyHiK5 said:
Certainly wont hurt between now and monday
Click to expand...

What about between now and... next year.. Basically, do I need to go get a 35'er, and keep this as a spare? Or did I basically put one of those "Super Start" caps on there..
 
well aren't you getting ready to move?
If you knowingly leave the wrong cap in there I think you would open the dorr for non disclosure if anything ever went wrong...

For $20, I buy then right one when available....lot cheaper than a compressor.
 
Don't get me wrong, I'm not trying to screw the buyer, just wondering if it's really a big deal. If anything, this will make a good spare..
 
How do you suppose a "Super Start " capacitor works ?
 
It must be capacitor week. I just replaced ours this week too. I work for a HVAC company ( I personally don`t know crap about HVAC) One of the guys handed me one that was 5 microfarads under my old one. He didn`t really explain why, but said it`s better to be 5 under than 5 over. Next time I see him I`ll get him to explain.
 
http://forum.allaboutcircuits.com/showthread.php?t=1223

It sounds like you have a two-part cap. The start/run style they talk about in that article. I would be more concerned about the run portion than the start portion. (The 5uf portion of the cap.) The start section is only used for a fraction of a second, and it's only intended to induce a lag in the current to an alternate set of windings to allow the motor to self-start. And difference is really within the tolerance range of most electrolytic capacitors. I personally wouldn't worry about it, but if it makes you feel better, get the proper size. Your comfort is important, too.
 
hvac dude here. its a dual capacitor, for the compressor and outdoor fan motor. they combine them instead of having 2 separate ones. they just share the comman. the 35 mfd is for the compressor, the 5 goes to the fan. i wouldent lose any sleep over it. itll be fine, no problems. your cap will be labeled fan, comman, and herm(or comp).
 
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