Results 1 to 14 of 14

Thread: Capacitors on Home A/C unit

  1. #1

    Question Capacitors on Home A/C unit

    What do you kids know about A/C capacitors? I've had them pop the top in the past but do they slowly fail?

    The A/C here at the house seems like it has to work to get the compressor up to speed. But everything is functioning as normal.

    Do capacitors slowly fail?? If you have a drop in Capacitance wouldn't it affect the ramp up of the A/C compressor??

  2. #2
    Team Cheap Bastard
    President & Founder
    sammm's Avatar
    Join Date
    Jan 2004
    Location
    NRH, TX
    Posts
    6,127

    Default

    I know my pool pump capacitor will act up before it fails totally. Electric motor getting noisy is the first sign.

  3. #3

    Default

    It is hard to describe but it sounds like the A/C compressor is working a bit longer to get up to speed. But after it gets up to speed it sounds normal and the house is cooling as it should.

    I may also just be paranoid.

    I plan to give the outdoor unit it's biannual cleaning this weekend. Wondering out loud if I should toss in a new Capacitor and Contactor.....

    I don't have a capacitance meter that reads high enough to test the Capacitor.....

  4. #4

    Default

    I have had 2 capacitors go bad (house has 2 AC units). Both looked like coke cans left in the freezer, and there was no intermittent issues. They worked until they didn't.

    The compressor is slow, or do you mean the condenser fan? I had the condenser fan go on me once and it was slow starting, then would take a hand start to get it going. I found one locally on a Saturday that I got for about $150 w/ a new capacitor and it took all of 15 minutes to install.

  5. #5

    Default

    I've had the Capacitors do the frozen coke can trick. I've also lost condenser fans and the contractor over the years.

    The compressor is what sounds like it is starting slow to me fan seems normal(ish).

  6. #6
    Team Cheap Bastard
    President & Founder
    sammm's Avatar
    Join Date
    Jan 2004
    Location
    NRH, TX
    Posts
    6,127

    Default

    I've had cap's go bad and did not swell up at all.

  7. #7

    Default

    Quote Originally Posted by sammm View Post
    I've had cap's go bad and did not swell up at all.
    ^ Lies!

  8. #8

    Default

    Given Caps are cheap and will go out eventually anyway, I would go ahead and get a new one and see if it helps. If it is the compressor, I think you need to pay a pro to come out as it would involve disconnecting the refrigerant lines. A $30 cap replacement gamble seems worth it to possibly avoid stupid service call fees.

  9. #9
    Team Cheap Bastard
    President & Founder
    sammm's Avatar
    Join Date
    Jan 2004
    Location
    NRH, TX
    Posts
    6,127

    Default

    ^Good call. Cheap enough to swap the cap and see if it acts any differently. If it's not, you have a spare for next time.

  10. #10

    Default

    How to change the capacitor? Just pull it out and push the new one in?
    Gabriel

  11. #11
    Team Cheap Bastard
    President & Founder
    sammm's Avatar
    Join Date
    Jan 2004
    Location
    NRH, TX
    Posts
    6,127

    Default

    ^Yep. Turn off the breaker first, then jump the 2 terminals with a screwdriver or something to totally discharge it. Then unplug the leads, and pop a new one in.

  12. #12

    Default

    Quote Originally Posted by sammm View Post
    ^Yep. Turn off the breaker first, then jump the 2 terminals with a screwdriver or something to totally discharge it. Then unplug the leads, and pop a new one in.
    Yea don't forget the part where you strip down the A/C unit so you can get to the electrical panel.

    I wished I had a way to measure the Capacitor but I don't... I'll give the outdoor unit a clean up first thing in the AM and see if can grab the specs of the prints or the cap itself. I think it is a 55/5 cap. May just replace both the capacitor and contactor.

  13. #13

    Default

    Yes they can slowly fail. You can test it with a meter. I just replaced one on my downstairs unit yesterday, took 10 mins.

    I would pull the outside fuses for the unit before proceeding. Make sure you get the right capacitor for your unit, they are labeled in MFD, should be something like 35-5 and if you have a 440 volt currently don't downgrade to a 370 volt.

    https://www.youtube.com/watch?v=c8YPHLxzzCA&t=288s
    VW Bug in running shoes
    M Porcupine sedan
    M Porcupine coupe
    Crusty old e46 beater
    Battery Powered appliance car

  14. #14

    Default

    I woke up at the crack of Dawn on Saturday and cleaned out the outside unit. It was a touch dirtier than I figured it would be but it cleaned up nicely. (I try to clean it out 2 times a year)

    Got a couple pictures of the Capacitor and the Contactor and pulled the original documentation out of the unit.

    Figured out it has the wrong Amperage Contactor in it 30A should be a 40A and no telling how old the Capacitor is so I plan to Amazon up the parts to refresh everything.

Similar Threads

  1. Sony CD unit
    By jelliott25 in forum dfwMiata.com Classifieds
    Replies: 0
    Last Post: 11-25-2015, 03:15 PM
  2. WTB: OEM stereo unit 90-97...must be working :-)
    By Bob_MX5 in forum dfwMiata.com Classifieds
    Replies: 5
    Last Post: 04-06-2015, 10:55 AM
  3. Portable A/C unit?
    By POS Racing in forum Bull
    Replies: 87
    Last Post: 08-02-2011, 01:54 PM
  4. Need some info on SC unit
    By IPRESS in forum FI Miata Tech & Chat
    Replies: 4
    Last Post: 05-21-2008, 07:31 PM
  5. oil sending unit
    By doc in forum Miata Tech and Chat
    Replies: 1
    Last Post: 08-20-2004, 05:35 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •