He charged me 168. But at least I have ac!!! I really wished I had that damn volt meter.

 

Still curious why my capacitor keeps blowing. He suggested that it was the compressor but would charge more to look at it.

 

Well I would start by looking at the capacitor and see if it is a 370 volt or a 440 volt. If it is a 370 volt buy a 440 volt. You can always go up on voltage of capacitors but never lower. Also, never use a different microfarad rating. Only use what is called for by the motor manufacturer. If it takes a 30/5 dual, get a 30/5. For instance a 35/5 or a 30/7 will work but will also cause problems with the motor that has the wrong capacitance, some people say you can go 2% difference, but I don't recommend that, in a pinch on a weekend when the wholesaler is closed, yeah maybe, but only until you can get the right cap. You also don't need to get a dual, you can get separate caps for the compressor and fan but much more convenient using a dual, also saves space.

Again, if you have a 370 volt cap, upgrade to a 440, but keep the microfard correct. Caps are manufactured cheaply, they are probably one of the most common problems for peoples systems not working and motor failures. You could ohm out your compressor and fan to see if you have high resistance values, you could megohmmeter to check for winding insulation is starting to go, but that is a something that really needs a baseline at new or over time to see if there is a change.

This is dangerous and should only be performed by someone who is qualified to do so. If you feel you are capable of doing this, go for it, keep in mind this can kill you if you don't do it right. Check the voltage at the capacitor terminals to see what you are getting back. This will be somewhere in the 350-440 volt range. If your cap is a 370 volt and you are measuring 400 volts, you need to get a 440 volt cap. If you have a 440 cap and you are measuring over this then I would get a qualified HVAC technician to your house to diagnose the issue. Keep in mind these capacitors I am speaking of are run capacitors, not start capacitors.

 

I took my old one to grainger and the matched it up. The tech told my wife that the compressor could be starting to go sending a spike in amps to the capacitor. He also said it would cost more to look at. I wasn't home and could be getting a different story from tech to wife to me.

 

Old capacitor

 

 

I would check voltage to cap at start up between c terminal and herm terminal to see if you are going over 440 volts. I would also check amp draw on compressor to see what locked rotor amps and full load amps are.

How old is the system? How often are you replacing caps?

 

Unit is 10yrs old and this is the second time in 3yrs I have replaced caps

 

I would also try a different manufacturer of capacitors, seems like the original lasted a normal life span and it was replaced with questionable quality caps. Not saying those caps are junk, but I would try a different manufacturer.

I would try going to a wholesaler or calling them, they probably wont sell to you, but they might, and give them the model and serial number of your condensing unit and ask them if they can verify what size capacitor needs to be in unit. Just as a verification that you have the right size cap for the compressor.

If it is the right size, and this one fails, I would ask them if they would sell you a cap preferably from a different manufacturer. Also if it fails again, I would look at some of the other items already discussed. Amp draws, voltages on start up and running, ohm out the compressor, or megohmmeter the compressor, and another thing I would look at for preventative measure would be the contacts on the contactor, look for pitting on the contacts and signs of arcing. If you are getting this far into it, unless you know what you are doing I would call a service tech.