Replaced heat pump cap. does it need to charge?

Discussion in 'HVAC Heating & Cooling' started by digdugger, Aug 12, 2016.

  1. digdugger

    digdugger New Member

    Joined:
    Aug 12, 2016
    Location:
    Arizona
    Last year I replaced a messy, leaked capacitor that goes to the exterior coils big fan on my 30+ yr old Trane roof heat pump. Oddly enough, the wire connectors on the old cap were both wired to the same terminal side. For the new cap I put one wire on each terminal. (not both on one as it was before). The fan would not run though when the A/C turned on. So I put them both on the same terminal and it began working. I know this is wasteful for energy though and its not using the cap at all in this case, the electricity is just using the terminals on the one side to pass through to the fan (basically one long wire).... Does the cap need to charge for X number of minutes first? That's the theory I have (but don't know if it's true) and I plan on climbing up there to try it again but thought I'd ask the experts. I just bought a cap meter too to check it. (it's not an ESR meter though).
     
  2. WorthFlorida

    WorthFlorida USCG escorting cruise ship leaving Port Everglades

    Joined:
    Oct 28, 2009
    Occupation:
    Retired
    Location:
    Orlando, Florida
    How about a picture to see these terminals and the cap. What I'm reading is both leads of the cap are on the same terminal, that means tie together? Is is a two or three terminal capacitor. Many systems will used the same cap with three terminal with two different values. One is for start up and the other is for run. This cap is not doing anything and no there is no charge up time on any cap other than a few micro seconds and there is no energy being wasted. As old as this system is, is there any wiring diagrams left on the inside of the covers to the condenser/fan relay and cap.
     
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  4. digdugger

    digdugger New Member

    Joined:
    Aug 12, 2016
    Location:
    Arizona
    See attached pictures. There are no caps with 3 terminals. The cap that won't work right unless both wires are on same terminal is a 7.5uF (pic 0503...same cap is shown in pic 0504 in bottom right..i know you can't see the wires, sorry). I did try it again by the way. When I put one wire on each terminal, the condensor fan makes a loud noise and moves very slowly. Move both wires back to same terminal it comes on immediately and with full force. By the way I just went thru and replaced all caps in this unit, except the one in question which measures at its rated farads. But the problem with this cap existed before and after.

    I'm also posting pics of ALL caps... First of all, what I think is the model # of the Trane is pic 0498. I found no schematic inside anywhere. Pics 0504 (left side) show two caps that are jumped together with a red wire. Pic 0505 is a close up. The one with a resistor is a 135-162 MFD. The other it's jumped to is a 40MFD. Pic 0501 shows a 10uF cap thats wired in line (well has connectors but is zip-tied to wires) to the condensor fan motor. Pic 0495 shows squirrel fan motor cap 12.5uF. I asked the HVAC store lady (she admits she knows little but her husband works in the field) why the one cap was jumped to the other and she said some repair people will put another cap in to help an old motor? She had no clue why the one cap wouldn't run cond fan motor without being on same terminal.

    I suppose it's possible that one or more of many different repair people over the years have screwed with (or screwed up!) the caps wiring. (several families have lived in this house before us). AZ has some fame for attracting a fair amount of shady contractors.
     

    Attached Files:

    Last edited: Aug 23, 2016
  5. WorthFlorida

    WorthFlorida USCG escorting cruise ship leaving Port Everglades

    Joined:
    Oct 28, 2009
    Occupation:
    Retired
    Location:
    Orlando, Florida
    You're right about it being hack up a bit. Someone may have added a kick start set which includes an additional cap. Without a wiring diagram, if it sis running, leave it alone but you should seriously look into replacing the unit. Your efficiency will jump up quite a bit, save your electric bill and be more comfortable and it will not fail the day before your daughter's wedding or some other important event.

    Check with your power company for any rebates. Now a days almost all utilities companies have some kind of rebate incentive to upgrade A/C units. Also some manufactures might have a rebate program.
     
    Last edited: Aug 24, 2016
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