HVAC experts - capacitor question

[sciphi]

The condenser fan motor on our 15 year old central A/C condenser went out over the weekend. I replaced the burned-up motor with a new motor and new run capacitor sized for the new motor. The capacitor I was sold a 35+7.5 MFD capacitor since the new fan motor needs a 7.5 MFD run capacitor to work. The old capacitor was a 30+3.0 MFD capacitor. Neither I nor the local warehouse that sold me the new motor and cap caught the discrepancy in the cap size for the A/C compressor run cap. The A/C works very well for the moment.

My question is: How long do I have to get a replacement capacitor of the correct size? Or, is it even an issue?

 

[Quest]

the difference between your old one(30+3.0uF) vs the new one came with the motor (35+7.5uF) is miniscue, and minimal difference during operation.

So long as their operational voltage ratings (in terms of VAC) are same or higher for the new one, you'll be in ship shape.

No need to fuzz over that extra couple of uFs.

Q.

 

[Leo99]

My AC unit likes to blow up capacitors. I keep a couple spare on hand. The first time it blew, I had to call in the HVAC professionals to troubleshoot it. Cost me a few hundred dollars. Second time I ordered the capacitor off the internet for about $50. Then I found a local store selling them for $8 each.

I recommend you shop around and keep a spare just in case.

 

[bullwinkle]

In compressor run caps, a little too big is better than too small-it'll eventually start to dry out & the capacitance will actually drop into the correct range.

 

[sciphi]

Not an issue, in other words. The motor part of the cap is sized correctly. The compressor side sounds like it's within range of error.

 

[Donald]

So this is two capacitors in one can?

 

[HerrStig]

Originally Posted By: bullwinkle
In compressor run caps, a little too big is better than too small-it'll eventually start to dry out & the capacitance will actually drop into the correct range.
+ 1

 

[DBMaster]

Originally Posted By: Donald
So this is two capacitors in one can?


Yes, that is correct. I bought a capacitance tester on eBay for about $14. Not a bad investment for the future. It is very easy to use.

 

[sciphi]

Originally Posted By: Donald
So this is two capacitors in one can?


Yes. About 4" high and 2" in diameter.

 

[coolbird101]

As others have mentioned, you are fine with the slightly larger run capacitor, a slightly larger run capacitor actually increases starting torque and lowers running amperage.
I should mention that the industry is now flooded with capacitors made in other countries, these capacitors fail often. Make sure you buy capacitors that are made in U.S.A. , as they are much more robust and reliable.

 

[DBMaster]

The OEM capacitors used in the units made by my employer are pretty much all made in China (Sheng Ye) these days. The one in my 2005 vintage Rheem unit is made in Mexico. OEM caps are generally required to last through more cycles than cheaper aftermarket replacements.

You CAN get good caps from other countries IF you maintain good specs and don't look at cost as the #1 driving factor in purchase decisions.

But, I have heard from a number of techs that capacitors do fail more frequently than they did a decade ago. Keeping a spare around is not a bad idea.