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cannesdo's avatar
cannesdo
Explorer
Oct 20, 2016

Aaaaa...Now the main A/C is out....

I have two A/Cs...the one in the living room (Duo-Therm -- ducted) turns completely on and then completely off throughout the day. The bedroom A/C (Mach 8) sounds like it's on all the time but the compressor cycles on and off, you can hear it starting and stopping.

Well, the living room A/C just made that sound but it's not a sound it's ever made, and after that it was just blowing like a fan even though it was set on A/C. The air is not cold. What are the possible causes? Does the compressor sometimes just die? It's 15 years old. Any suggestions about what to check and how would be appreciated. I'm pretty mechanical and don't want to pay for any more labor than I have to. I've replaced the motor in my furnace.

It was just running on low when it happened. Sort of a clicking sound, like the other one makes when it's cool enough inside and the thermostat tells the compressor to shut off. But I knew immediately it's a sound the main ducted A/C doesn't ever make and shouldn't be making.

Thanks!

Ok, wait...now it's blowing cold air again. For about 10 min. it wasn't.
  • j-d's avatar
    j-d
    Explorer II
    Oct 24, 2016
    Any progress? I saw the references to Harbor Fright above. I carry their cheap AC clamp-on ammeter. Not the best, but it has been very satisfactory. Any DVOM will help in troubleshooting, but one with Capacitance is really helpful for A/C. I'm blessed to have a Fluke 12 as a gift from a friend. With that, I can check capacitors without having to get one, substitute one, etc.

    HF has meters with that feature and more. There are also some All-In-One meters, mostly from China, that can do ordinary DVOM functions plus AC/DC Amps, Capacitance, Frequency (nice for your generator) and more. $50 or so there.

    To do any of this testing, you have to climb up onto the roof, take the cover(s) and internal shielding off the A/C, and have somebody on the ground to turn power OFF while you work then ON for your testing. If you aren't comfortable with that, PLEASE don't jump into it. Service calls are way cheaper than injuries.
  • sdianel_-acct_c's avatar
    sdianel_-acct_c
    Explorer
    Oct 21, 2016
    You can first try a thermostat reset. If that doesn't work, our AC's both started acting up in hot and humid temperatures. We called the tech who was booked up for 2 weeks. His wife told us to turn both AC's off for awhile, then turn them back on with both AC fans on HIGH. She said leave them on high. She said that in humid conditions the AC freezes and shuts down. Since we have followed her advice our AC's have worked perfectly. We did have to replace one of our AC's at 11 years that had a leak in the refrigerant tube (small hole underneath that wasn't found by 2 other techs).
  • cannesdo's avatar
    cannesdo
    Explorer
    Oct 20, 2016
    time2roll wrote:
    I would get an amp draw reading and compare to specs.
    15 years is a good run for a compressor.


    Ok, any chance you or anyone could talk me through that?

    Thanks...
  • doxiemom11's avatar
    doxiemom11
    Explorer II
    Oct 20, 2016
    You may want to set your fan to "hi" instead of low. From all I've read, it will freeze up easier/faster on the low setting especially if it is humid outside.
  • time2roll's avatar
    time2roll
    Nomad
    Oct 20, 2016
    I would get an amp draw reading and compare to specs.
    15 years is a good run for a compressor.
  • cannesdo's avatar
    cannesdo
    Explorer
    Oct 20, 2016
    It was doing great in 100+ temps. Why would it freeze up now that it's 90, and the day after I put insulation in the windows, helping it out even more?
  • cannesdo's avatar
    cannesdo
    Explorer
    Oct 20, 2016
    Thanks for your help. It just did it again. It was on high for a while. Turned it down, and after about 20-30 min I heard a little knock, then immediately felt the air turn from cold to a warmer air, but not necessarily warm, just not cold.

    Wouldn't the high setting make it even icier?

    No hum, no burning rubber smell... I guess compared to the A/C cold air this other air might smell a little musty.
  • down_home's avatar
    down_home
    Explorer II
    Oct 20, 2016
    If it was operating and then stopped especially on low and air smells musty and damp perhaps water dripping from it, it frozen up. If it keeps running trying to cool bu not quite getting the job done ice will form around the condenser.
    It should be set on auto or high and if the problem persist the unit may need a good cleaning.
    If you smell burning rubber whe you try to start it and hear a humm or the fan tries to start or runs but the compressor doesn't, check the run start capacitor.
    Most shops have them in stock and different kinds can work. Try not to buy a Chinese unit. They do make American condensers too. Run maybe up to ten bucks more but they last longer.
    If you can sometimes get the unit to start by turning off the switch at the thermostat it may be the sail switch, of the thermostat. They plug in easily.
    Most RV and RV mobile Techs have them all.
    If you are in a large or maybe even small RVing community you may have everal RV Mobile Techs around. They have seen it all and can get it fixed in a minute or two. That is experienced Techs.

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