Friday, March 15, 2013

Front A/C Capacitor Replacement…

BCS 025When our front Coleman A/C/Heater unit went on the fritz less than a month ago we were worried that the compressor had gone out in it. We were also a bit concerned about how much this would cost us. You see one night after I had gone to bed Sharon switched on the front electrical heater unit and she heard a loud humming noise and noticed a bad smell that she thought might be something burning.

So she woke me out of a dead sleep, much to my dislike. However, smelling something burning is not something to take lightly in an RV. So after waking up a bit and trying to analyze the situation I had deduced that the heating unit was bad and that we likely lost the compressor. I assumed the hum was the compressor trying to start and the smell was it getting too hot. The burning smell reminded me of a smell I had experienced before when a motor had burned out.

BCS 028So the next morning I started reading the internet to see what I could do to further troubleshoot the situation. Everything I had read pointed to the start capacitor and not the compressor. Well if this were the case it would cost a whole lot less than replacing the compressor. I called a electrically astute buddy of mine and we climbed up on the roof and removed the A/C cover and unscrewed the 6 screws that were housing the start and the run capacitor’s (above left photo). Nothing appeared to be burned or scorched but after removing the retaining screw on the band that held the capacitors in place there it was… two burnt spots on the start capacitor (above right photo in the bottom right edge of capacitor and on the cap lower edge of it).

BCS 011   BCS 009

BCS 013A email to Tiffin verified that this was a 88-108 mfd start capacitor and the likely culprit and this replacement part from Tiffin was $36.00. A call to the only RV parts place in town resulted in them having one for $38.00 and it was in stock. I picked up the capacitor and my buddy and I replaced the suspected bad one in the front A/C, Thanks, Jimmy! Then with fingers crossed I turned on the A/C and viola…. no hum and no burnt smell. We now have a perfectly functioning front A/C just in time for the predicted 80’s temperatures forecasted for this weekend. After all that hard work Sharon and I paid a visit over to one of our favorite College Station restaurants, Los Cucos, to get our favorite Gallitos Fish Plate…. mmm mmm mmm mmm mmmm……….

NOTE: You must be careful some capacitors will require discharging before removal otherwise a jolt of electricity may be discharged through you when removing it. A useful document on Capacitors can be found here.


  1. Always nice when a repair can be made for $38 rather than for hundreds. Glad you are up and running again and hopefully you took Jimmy with you to Los Cucos!

  2. Great fix job, and good to post a pic and explanation and warning about the jolt! I love blogs like this... and the "happy endings" with a small price tag too. (better than the sorry stories about some disreputable repair place fleecing them for a whole new AC unit when it was only the capacitor!)

    Karen and Steve
    The USA Is Our Big Backyard

  3. Always good to fix it yourself and save some $$.

  4. Great job of deducing and fixing the problem. So glad it was a $36 problem and not the compressor. Thanks for the heads up on the discharge and the link. And REALLY nice to have knowledgable friends to help out.

  5. Which one of these did it look like (or was it rated like)?

  6. Glad you got that fixed. 80 degrees and no ac would not be good.

  7. Our starting capacitor did the same thing, and after doing some research, we went with a Supco replacement.

    It will start the compressor a little easier, and is much more durable than the 88-108.

    So far, so good. It is in the mid 90's right now in Palm Springs, so we are giving it a real good workout ... LOL.

    Take care ... TnT

  8. Good job on the repair.

    Every time I hear capacitor, I think of the flux capacitor in the "Back to the Future" movies.

  9. Nice to get the job done for a reasonable price, in time for the heatwave.

  10. Hello from another John & Sharon! I was going to contact you earlier, but since I already helped out over at TinyCamperBlog, I feel like I am on a roll to help out again with an electrical issue.

    First off I am a retired master electrician and robotics technician, and have taught troubleshooting classes. I always carry both a digital multimeter as well as an analog multimeter, as they both have specific uses. To test a large motor capacitor, an analog meter works best, even if it's a cheapy $10 one. Although your "blowout" was visually obvious, most capapcitors will simply fail with no visual indication. If ever in doubt, shut off the breaker to the unit, and once you get it open, first make sure the capacitor is discharged by shorting across the terminals with a screwdriver. A capacitor stores electricity, but only for a short time. Once shorted it's dead. Set your analog meter to a mid-range continuity setting. Then touch the leads to the terminals. If the capacitor is good, you should see the meter needle quickly rise and then slowly fall. Then reverse the leads and do it again. It should work both ways, but it won't work twice the same way.

    If the capacitor is shorted it will peg the meter and stay there. If it's open, the needle won't move. Either one is an idication of a bad capacitor. Even if good, this won't give the you the "value" of the capacitor (which could also be off tolerance) but it will give you an indication of whether it's working... and usually they either work or they don't. Better than 95% of the time, this quick check will tell you if the capacitor is the problem or not.

    Also, capacitors are a pretty generic breed of part. As long as the voltage and farad value is the same, any capacitor will work, so don't "assume" you have to get it from an RV dealer, which usually has higher prices, or even that it has to be identical in physical characteristics. Different manufacturers make them in metal as well as plastic cases and in both oval and round shapes. W.W. Grainger stores are located in nearly every major city, and some cities have more than one. Or you can order online, and they can match nearly any capacitor on any motor and even the motors themselves. Any HVAC repair facility can also come up with a match, so always check prices. There are very few parts on any appliance (other than the outer shell) that is proprietary to the manufacturer. Nearly everything on the inside is generic.

    Hopefully, this will save someone else a huge repair bill in the future.

    If anyone has any specific electrical questions I will be glad to answer free of charge.

    1. a lengthy reply but one with very useful information, thanks for the reply and hopefully it may help others...

  11. Oh, glad it was fixed immediately before the bad temperature hit you. I think we need to check our A/C unit in our RV, too, before this thing happens to us. I don’t want my wife to wake me up in the middle of the night just for this thing. Anyway, good job on the repair. You’re pretty lucky it wasn’t very expensive. ->Oma Gammel

  12. Whenever you heard a loud humming noise and noticed a bad smell that she thought might be something burning. keep it repaired. AC repair Magnolia

  13. You must be careful some capacitors will require discharging before removal otherwise a jolt of electricity may be discharged through you when removing it. Air Conditioning Repair Portland