Heatpump Help

I noticed today one of our heatpumps wasn't working. The air handler fan turns on fine but the compressor and fan won't turn on outside. The last time I had this issue it was just the fan and I could jumpstart it by spinning the fan (because the compressor would still turn on) and a new capacitor fixed that problem very easily. This time neither the fan or compressor will turn on, though I can hear a single click when turning the unit on or off via my Ecobee app.

Anyone have an idea how I can troubleshoot this?

Comments

  • rpf65
    rpf65 Posts: 2,127
    Probably a capacitor again.

    You could have a high pressure that needs to be manually reset, or a safety switch in you drain line/pan tripped because the drain line is clogged.

    These are the most common problems.
  • Airplay355
    Airplay355 Posts: 4,298
    Worth it to just grab another capacitor and try it out? It was $11 last time (about a year ago).

    I checked the drain pan and it's dry as a bone. There was some blown in insulation in the pan and around the sensor. I thought maybe if the sensor was messed up then the air handler wouldn't turn on either, is that right?

    I haven't checked the drain line. I also assumed that would be fine since is seems like there's never any condensation in the drain pan. Maybe I need to stick a shop vac on it and try clearing it out just in case.
  • rpf65
    rpf65 Posts: 2,127
    Drain line will have a cap on a bushing with 2 wires coming. Not all systems have installed. Recommend pouring a cup ov vinegar down drain line once a month during cooling season to keep clean.

    Some condensers, outside unit have a manual high pressure switch that can only reset manually. That could be tripped.

    You may also want to check breaker box for a tripped breaker, and you may also have a fused disconnect.
  • Airplay355
    Airplay355 Posts: 4,298
    Breakers weren't tripped but I reset them just in case. I poured vinegar down the drain line and it came out fine outside. Discharged both capacitors with breakers off and then turned everything back on. Now it's running and blowing cold. So strange. Gremlins?

    I ordered new capacitors just in case. I forgot there were two in there and I only replaced the fan capacitor last year, not the compressor motor capacitor. The motor one looks like it's been replaced before and is a no name made in China one. Who knows how old it is, but how long do these last? Couple years? The unit is 11 years old.
  • mrbigbluelight
    mrbigbluelight Posts: 9,199
    With someone inside the house at the Tstat and you ouside at the condenser, have them cycle the unit on while you watch the contactor outside.
    Does it pull in ? You might have to wait a minute as I'm sure your unit has an "Anti Short Cycle" control on it.

    If the contactor doesn't pull in, can you manually push in the contactor ? If so does the unit fire up ? If it works manually, it might be that the coil is bad.

    ......stay cool B)
    Sal Palooza
  • rpf65
    rpf65 Posts: 2,127
    Depends. Some will last close to forever, and others will blow up in 6 months. The ones I use off the work truck have a 5 year manufacturers gaurentee, and seem to be pretty good.

    Could be you just had a glitch in the defrost control board, and cycling power reset it, like every other microprocessor based thing on the planet. Glad it worked out. I tell my customers than one reset once in a great while is a glitch, two or more is a problem.
  • JimKellyfan
    JimKellyfan Posts: 696
    That click, is there a relay in the set up that could have gone bad ?
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  • Airplay355
    Airplay355 Posts: 4,298
    I suppose there could have been but it seems to work fine now. The only thing meaningful that I did was discharge the motor capacitor. It blew up and melted the connector a little. I was expecting more of a quick zap as opposed to a loud pop and some melting. Is it possible for those to overcharge?

    After I did that everything went back to normal. Very strange.
  • rpf65
    rpf65 Posts: 2,127
    Heat pumps have a defrost control board that the signal from the thermostat must pass through before the unit will start. Since it restarted by cycling power, it’s unlikely that a pressure switch is defective or sticking.

    A weak capacitor could have caused the thermal protection switch is the compressor to trip, and it went into lock-out mode. Most units have a 4 hour lock-out, unless it is reset, usually by turning the power off. Many defrost control boards are powered by the indoor unit, so cycling power to the air handler could also reset it.

    Others still while being powered by the indoor units receive a few signals from the outdoor unit’s components, and while being a passive signal can cause a glitch in the control board unless power is removed. Lennox had a big issue with this on one or two series of 2 speed condensers about a decade ago.

    Considering that the unit restarted after cycling power, and it isn’t a frequent condition, I wouldn’t worry about it too much. In the most common order that I have personally experienced a recurring issue like this is:

    1. Drain line that is partially clogged causing slow drainage. Trips the safety switch located in the drain line.

    2. A weak capacitor. On hot days, even with the built in delays, the compressor could be restarting before it cools down sufficiently. Compressors draw a lot of current on start up. A weak capacitor will cause even larger current draws, and could potentially destroy the compressor.

    3. Bad breaker. It happens.

    4. Bad defrost control board, heat pump specific but many of the higher end condensers also have control boards. The primary job of the control board in any out door unit is to protect the compressor. When in doubt no start condition.

    5. The compressor is ready to die. This condition will cause frequent no start conditions. A hard start kit can sometimes by you a little time to decide if you want the compressor replaced, the condenser replaced, or a system replacement.
  • Airplay355
    Airplay355 Posts: 4,298
    Thanks very much for all the help! I’ll make sure to keep checking on things and hopefully can get a few more years out of this system. It’s 11 years old and isn’t exactly top shelf stuff. Fingers crossed :)