My A/C just died. The A/c guy came and said the capacitor is bad. He said my old capacitor is 35+5 but, he doesn't have any in his truck. He replaced it with a 40+5.

He said he'll come back to change the capacitor back to 35+5.

The A/C is working now after USD350 charge but, I wonder what's the difference between 35+5 and 40+5?

Will my A/C unit or my house blow up?

Will my A/C unit or my house blow up?
No. A capacitor works by creating a difference in the timing the current gets to the start windings and the run windings. This is necessary to get the compressor started. Also creates a difference in the timing between the windings when compressor is running.
Oversizeing the capacitor by 5 microfarad is not much.
About like putting a hard start kit on it. Probably not quite as efficient energy wise as it could be but should be all right for short time.

About like putting a hard start kit on it. Probably not quite as efficient energy wise as it could be but should be all right for short time.

Besides the energy efficiency, will it do any harm to the A/C unit?

They have not come back to switch it out. I'm concerned it'll hurt the unit with the extra hard start "kick"?

As long as it's temporary, no harm will be done.

As long as it's temporary, no harm will be done. How long is temporary? I have a new question - another tech "supposedly" came out today to replace the capacitor. No one was home, so, not sure if he actually did. He claimed that he replaced it with a dual run capacitor. I went to look when I got home and it still looks like 40+5 with 440VAC. When I called the company, the operator claimed that was the part that was needed. I requested the tech to call me back... and he did. He claimed that part was what the manufacturer recommended and that was the reason our old capacitor blew out. The problem with that statement, the old capacitor was working fine for the last 10 ++ years. So, is he feeding me some BS?

What's the difference between dual run capacitor and capacitor?
Edit: Based on http://www.hvacpartsoutlet.com/troubleshootacapacitor.aspx ; my original capacitor was a dual run capacitor.

My A/C unit make and model - carrier 38tkb030320

This is my old capacitor model
http://i61.tinypic.com/fvbg45.jpg

This is the new capacitor the techs installed
http://i62.tinypic.com/1yju4y.jpg


Anyone can tell me if these are comparable / interchangeable?


Thank you very much

To make sure what size you need, take a look at the compressor label. It will tell you the MFD. A dual cap is just 2 caps in one housing.