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Capacitors
Posted on 7/15/21 at 9:12 pm
Posted on 7/15/21 at 9:12 pm
Followed advice from many members here and ordered some spare capacitors for my AC units. Came in handy tonight as I went upstairs and it was 86 degrees. My condenser fan wasn’t running but my air handler was, so I pulled the breaker and looked at the capacitor. Didn’t look all the old abs wasn’t bulged but since I had the spare I went ahead and changed it out. Replaced the breaker and she fired right up. Saved my wallet from a service call and wife can still work in her office tomorrow. So a toast to the advice I received from members here.
Posted on 7/15/21 at 9:20 pm to Perrydawg
I have said it numerous times, get a spare capacitor and switch for your condenser.
Posted on 7/15/21 at 9:23 pm to WPBTiger
Yep yep, very common failure, very cheap part, very easy fix. No brainer to keep around.
Posted on 7/15/21 at 9:33 pm to Perrydawg
I got a spare last week per advice here.
Posted on 7/15/21 at 9:33 pm to Korkstand
Yep had two Chinese made capacitors but ordered some AMRAD’s to keep on hand because the one I changed was made in China as well.
Posted on 7/16/21 at 6:35 am to Perrydawg
Are capacitors all the same or specific to the unit? Can I just buy any capacitor I find online and use that as a spare?
I know very little about HVACs.
I know very little about HVACs.
Posted on 7/16/21 at 6:49 am to TDsngumbo
Each unit will use different rated capacitors (some still have separate caps for the compressor and fan).
There are maybe half a dozen different caps that are extremely common at best. The values are printed on the side, just match the values and you should be golden. Take a pic of the values and the wiring and keep it (it can/will save a lot of hassle later).
EDIT: Forgot, grab one for (each) air handler blower motor as well, should only need to remove a few screws to gain access to the squirrel cage, cap is often fastened to the outside of the blower.
There are maybe half a dozen different caps that are extremely common at best. The values are printed on the side, just match the values and you should be golden. Take a pic of the values and the wiring and keep it (it can/will save a lot of hassle later).
EDIT: Forgot, grab one for (each) air handler blower motor as well, should only need to remove a few screws to gain access to the squirrel cage, cap is often fastened to the outside of the blower.
This post was edited on 7/16/21 at 7:26 am
Posted on 7/16/21 at 7:46 am to dakarx
quote:
Forgot, grab one for (each) air handler blower motor as well, should only need to remo
Just a note/add on, PSC blower motors found in “older” or many “base” model air handlers do have a run capacitor, but EMC blower motors found in variable speed, constant torque, or newer HVACs do not have a capacitor. As I recall, as of 2020 PSC motors are no longer used in new HVAC air handlers, only EMC motors.
This post was edited on 7/16/21 at 7:25 pm
Posted on 7/16/21 at 10:32 am to TDsngumbo
quote:
Are capacitors all the same or specific to the unit?
they are like car batteries in that the voltage and capacity must match the application.
max voltage # needs to match
uhf # needs to match
size and shape often needs to match but these are pretty standard
finally if it needs to match if its a single or dual capacitor
so no, you cant just put anything in it
fan motors can use 5uhf, 7.5uhf, or 10uhf sizes
whereas a compressor could be 30uhf, 35uhf, 40uhf, or even 45 uhf
most, but not all, use the 440 max volt size
This post was edited on 7/16/21 at 12:02 pm
Posted on 7/16/21 at 12:46 pm to TDsngumbo
quote:
Are capacitors all the same or specific to the unit? Can I just buy any capacitor I find online and use that as a spare?
I know very little about HVACs.
I have always kept a spare. A couple years ago my old split unit died and I replaced. The new unit had a different capacitor than my "spare". I just got the installer to swap them for me. He said he uses the one I had all the time and there was no reason for me to just toss it...
He was making good money on the unit and it didnt really cost him anything to swap since they all cost about the same amount.
But Ill remember what he did when it comes time for more work or if I can recommend him to people....
Posted on 7/16/21 at 7:02 pm to keakar
quote:
max voltage # needs to match
Just to clarify, you can see some capacitors that state 370V-440V. What that really means is it is a 440V Max volt capacitor and it will also replace any other AC condenser fan capacitor under 440V. A 440V Capacitor can replace a 370V capacitor, but if a system really needs a 440V capacitor, then a 370V capacitor cannot be used to replace a 440V capacitor. It was confusing to a lot of people in the past that a 440V capacitor replaces 370V capacitors so some manufacturers stamp 370V - 440V on what is essentially a 440V capacitor.
It is critical to match the microfarads for a replacement capacitor and to get a protected capacitor if the one you are replacing says it is protected. A capacitor that is stamped +-5% is better than one than one that says it is within +-10%. In fact if you test a capacitor you should replace it if it is outside of a 10% range. They usually lose capacitance over time, so as an example a 40 mfd run capacitor that drops to under 10% (under 36 mfd) should be replaced as the capacitor is now providing less current to the condenser fan and compressor than is in a normal range. I just recently replaced a 40 mfd run capacitor that was the problem. My multimeter measured the existing capacitor at 35.2 mfd which is too low. I replaced it with a new capacitor that measured 40.7 mfd with my multimeter. That fixed my problem.
Capacitor size and shape do not have to be an exact match although generally if you have a round cylinder shaped capacitor you would replace it with another cylinder shaped capacitor that otherwise has the same specs. If the diameter is larger or smaller you will have to adjust the bracket or galvanized pipe hanger strap that secures it.
It is also nice to have a decent multimeter on hand that tests capacitance so that you can test existing and new capacitors to make sure that they are in +-10% of stated value. As always, treat any capacitor like a loaded gun and make sure you know how to safely handle them and discharge them or get an HVAC Tech to do the work.
This post was edited on 7/16/21 at 7:27 pm
Posted on 8/31/21 at 8:14 pm to Perrydawg
quote:
Followed advice from many members here and ordered some spare capacitors for my AC units. Came in handy tonight as I went upstairs and it was 86 degrees. My condenser fan wasn’t running but my air handler was, so I pulled the breaker and looked at the capacitor. Didn’t look all the old abs wasn’t bulged but since I had the spare I went ahead and changed it out. Replaced the breaker and she fired right up. Saved my wallet from a service call and wife can still work in her office tomorrow. So a toast to the advice I received from members here.
+1
Same thing happened to me this afternoon and was able to change capacitor and bypass my ac breaker until I get a new one tomorrow.
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