When I turn on my air conditioner at the thermostat the vents kick on but nothing outside. Also the last time that it worked it took a few minutes to get going and was pretty loud. I checked the electric all the way from the breaker box to the outside fuse box for the air conditioner and everything was good.

The unit is about 3-4 years old. When I took off the side panel I noticed a lot of rust and found that some of the electric tabs were ready to fall off.

Here are some pictures:

  1. Capacitor

  2. enter image description here

  3. enter image description here

There was a yellow wired that just crumbled when I touched it. I am guessing that was the culprit but could be any or all.

So questions are...

Is this a normal amount of rust for the inside of an air conditioner after a few years? The outside looks brand new, it sits under and overhang, and the area where the compressor is looks brand new.

All of the connections to both of these pieces is heavily rusted. What is the suggestion to fix? Where can I buy the items and all that good stuff? I am good with electric, just have never used caps or worked on air conditioner.

And lastly - how can I keep this thing from rusting out so fast in the future?

  • The black thing (relay/breaker not sure the name for it) and the capacitor are the source of the rusting problem. Their tabs are heavily heavily rusted. I know I have to replace these. Do they come with the unit or could have technician put his own in? Also this was COMPLETELY closed with no gaps... not really sure how moisture is getting in. I guess I will call goodman and see what they think. I will say this - one screw for the cover was also heavily rusted.
    – DMoore
    Commented May 1, 2013 at 14:04
  • You may find sourcing the replacement parts difficult, unless you have a local electrical/HVAC supply shop that is willing to deal to non-professionals. Though the internet often makes locating parts a bit easier.
    – Tester101
    Commented May 1, 2013 at 16:23
  • Do you think any of the issues fall on the manufacturer? As in will they ship me out some replacement parts. I know this stuff shouldn't cost much but I have a week or two before I can expect to use it. Not really even looking for freebies just want the right parts that won't start rusting so easy. I am also wondering why the tabs on the black thing and the capacitor rusted out way before anything else including the electrical connectors... I am seriously confused because this whole area of the unit is closed. It is like the installer put in old crap that was already rusting.
    – DMoore
    Commented May 1, 2013 at 19:05
  • Look for a sticker from the installer. Most companies that install these things will slap a sticker with their contact info on the unit. If the unit is still under warranty, claims and repairs will likely fall to the installer. It's not likely the manufacturer will want to deal with you directly, they'll likely shuffle you off to a local dealer.
    – Tester101
    Commented May 1, 2013 at 19:22
  • Also, it's not likely the dealer put bad parts in. The only thing the installer did (electrically), was connect power and signal wires. The contactor is simply not designed to be in a moist environment. The connectors are designed to work in a wider variety of locations, so they are a bit hardier.
    – Tester101
    Commented May 1, 2013 at 19:27

3 Answers 3


I would strongly encourage you to replace this unit (the Siemens component, not the entire AC) and replace the ends to those electrical wires. Simply put if the rust situation is that terrible I wouldn't be at all surprised if the integrity of the unit is already compromised, i.e. ready to fail you at any time. Your yellow wire is almost certainly why it's not working now, but it's a pain to fix it, and then have to fix it again only a few days/weeks later.

This is not a normal amount of rust; a great deal of humidity is getting to it, more than usual. I'm a Florida resident who had a 12 year old AC unit at one point that had been through a number of hurricanes and tropical storms, and it was only slightly oxidized, no rust. (Though I had to regularly open it for service because for whatever reason ants loved to commit suicide by throwing their bodies in between the electrical contacts)

To fix the rust you'll need to find where it's getting exposed to so much humidity from. Likely a seal or gasket is bad. You can either replace the broken seal/gasket or there are after-market products used as essentially spray on sealants. I recommend fixing it properly and replacing whatever seal or gasket is broken, but in a pinch squirting some sealant into the location that's leaking (with the AC OFF and given enough time to dry) will resolve minor leaks (depending on the severity).

  • Where does a non-pro get replacement parts for everything?
    – DMoore
    Commented May 1, 2013 at 14:09
  • there are a number of online suppliers (if you're lucky you can find a local hardware store that deals in such things but they are getting rare) try sustainablesupply.com I've not done much business with them, but I have no complaints about the results. Commented May 1, 2013 at 14:16
  • Replaced ends and contactor. Pretty sure whole thing was due to HVAC guy leaving tab open on the bottom and dryer exhaust blowing in there... So cost about $40 and duct taped the open tab.
    – DMoore
    Commented Nov 14, 2014 at 21:06
  • That'll probably cover it for you, just as a precaution I would check in on from time to time to watch for early signs of rust. Just incase the dryer Exhaust was not the culprit. Commented Nov 14, 2014 at 21:17

IMO that amount of rust is not normal. I live in Texas and it gets really humid sometimes. I've repaired both my last unit that was 8+ years old and my new unit that is 4+ years old and neither had any rust whatsoever inside the enclosure. Just ants and spiders for me.

I'd imagine that your relay is having trouble closing. After turning off the power you could use WD40 on it and manually push the relay in and out a bunch of times to work it in. Or you could go buy a new one. I think the part# is 45DG10AJA for your unit. That part is a single pole but you probably want to find out the double pole equivalent so that if one poles foobars down the road the other has a chance of continuing to work.

Most enclosures have a gasket around the edges that fit snugly against the cover. You can just use good 'ol weather stripping if yours is damaged or not there. It wouldn't hurt to use that foam in a can product at the top of the inside of the enclosure to prevent any water from leaking in up there too.

  • OK this is my being HVAC stupid. But why is one of my power lines going to where ever and the other to this contactor? If I get a DP contactor both go to it right? I think it is funny that the inside of this was as clean and dry as can be other than the contactor and capacitor. The residue at the bottom is just from me messing with the rust... It is like someone sabotaged this - I know they didn't but seems like it.
    – DMoore
    Commented May 2, 2013 at 6:20

I don't have HVAC experience but here's a few ideas you could investigate


For the wires, it might be best to cut off the corroded connectors strip a short part of insulation and crimp on new connectors.

For the spade terminals on the various devices you could use a wire brush to remove as much corrosion as possible.


To prevent future corrosion, I would try to identify the source of moisture and see if it can be excluded. Otherwise I'd use a corrosion inhibitor, perhaps WD40 would help (but I guess you'd have to regularly re-apply it) or maybe use something like petroleum jelly (vaseline).

  • 1
    Some Ox-Gard or similar anti-oxidant compound, would be better than WD40 or vaseline.
    – Tester101
    Commented May 1, 2013 at 16:19

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