Replies

1. 
   CapnMac | May 02, 2003 12:46am | #1

   Get the local Trane service tech on it.  Some compressors use a "motor starter," which is a big capacitor which helps the motor get started without dimming the lights so much.  If the unit is designed for a motor starter, and it is bad, there is only enough juice to run the fan, but not enough to start it--thus the hum.  The hum sould just be a relay holding open waiting for the fan to start, too.  The tech ought to be able to give you a diagnosis.

   Hopefully, it will be something simple like a fan relay or the motor starter.

1. 
   stanleyj2 | May 03, 2003 02:48am | #8

   Thanks,

   Your diagnosis was right on the money!  The capacitor had leaked oil and had a grey susbstance oozing from it.  I replaced the capacitor for $25 and it now runs like new.

2. 
   Len | May 02, 2003 01:40am | #2

   Stan,

   My neighbor had a Trane unit do the same thing at six years. After testing all the connections and the signal from the thermostat. I opened the side and found the wire nut had rattled loose. Some melted insulation and a burn mark. Fixed the wires and wrapped the wire nuts with electrical tape.

   Hopefully it's as simple as that. If your uncomfortable with electrical, call a service tech.

   Len

1. 
   DaveRicheson | May 02, 2003 04:52am | #3

   Loose wire, maybe, but the hum you here could also be a burned up contactor trying to pull in. Maybe a bad capacitor, but most of the time it is the start contactor. Take the cover off of the contactor ( with the power off at the disconnect) turn the unit back on and watch the contactor pull in. Chances are it has already arced enough to have burned up most of the points of contact. Good place to start. I get five or six of those every spring. They set there all winter and corrode what if left of the scortched points. First time they are started in the spring...poof.. they are toasted.

   Now if you don't know what any of us are talking about.....call Trane. No point in putting yourself or an expensive piece of equipment at risk.

   Dave

1. 
   NickNukeEm | May 02, 2003 04:13pm | #4

   Same deal last fall, only my Trane heat pump is 10 years old.  Burned contactor.  I've found you can only order parts through an authorized distributor, which there are none in this neck of New England, so I had to call the service tech to do it.  The visit and contactor cost about $150.  It took all of 10 minutes, as Dave described.

   I never met a tool I didn't like!

3. 
   BillHartmann | May 02, 2003 07:10pm | #5

   "The fan motor on the compressor unit outside is not turning and is making a humming sound."

   I think that all of the others missed the point that it is FAN MOTOR that is making the humming sound.

   If that is true and you can varify it by disconnecting the fam motor. If it is the fan and if you disconnect it the humming will stop.

   Of cousre you might be confused about where the humming is comming from.

   If it is the fan then the bears are frozen and it needs to be replaced.

4. 
   FrankTate | May 02, 2003 07:39pm | #6

   I have an old heat pump on a rental townhouse and had the same type of situation.  It sounded like the compressor was running but the fan was not turning.  Called the Service Co. (I have a service contract) and when the tech came out, he said that there is a defrost cycle  where the unit hums and the fan does not turn and that is normal.  So, for $45 I learned something new.  I hope your problem is as simple as mine!

   Frank
1. 
   DaveRicheson | May 03, 2003 01:49am | #7

   As Bill mentioned, do check the fan first. Turn the disconnect off, pull the grill cover and spin the fan blades. They should spin freely and coast to a stop. Hear a grinding noise, hard to spin, no spin at all, or stopping abrutley indicates a bad motor, before you dive into disconnecting the motor. If none of that happens, now is a good time to oil the motor bearings if there are ports for oil.

   Dave