On 8/24/2010 1:46 PM, cjt wrote:
On 8/24/2010 10:50 AM, jamesgangnc wrote:
On Aug 24, 12:31 pm, The Daring Dufasthe-daring-
wrote:
On 8/24/2010 7:18 AM, jamesgangnc wrote:





On Aug 23, 9:36 pm, The Daring
wrote:
On 8/23/2010 7:50 AM, jamesgangnc wrote:

On Aug 23, 6:47 am, wrote:
On Aug 22, 10:01 pm, The Daring Dufasthe-daring-

wrote:
On 8/22/2010 9:06 PM, ransley wrote:

My 1986 Lennox AC compressor unit just stopped running, the fan
isnt
running and no noise comes from the unit, I reset the breakers
and the
thermostat is the old round analog Honywell, its calling for
cooling.
Ive never worked on this but is there anything I can test with a V
meter before I call a pro. 3 weeks ago I lost all freon from a big
leak and had it fixed, all has been fine until today. I would
think at
least the fan would run.

If there was a thunderstorm, a voltage spike could have blown the
run capacitor. If your air handler fan doesn't run, it's a power
problem there because the 24 volt control voltage comes from the
furnace/air handler. Without the 24 volts AC, the condensing unit
where the compressor is will not come on. If you can push in the
insulated contact carrier on the condenser contactor and the fan
and compressor run, you'll know it's not getting control voltage
from the furnace/air handler.

TDD

What does the condensor contactor look like where do I find it, I
wonder if the tech left a wire loose since it seems like it just has
no power. I do know I dont think it was installed with proper gauge
wiring , Its about a 60 ft run of 2 pieces of 10 ga and it
rattles in
the pipe and at the breaker on turn on. All these years of rattling
could have loosened something.- Hide quoted text -

- Show quoted text -

I've never heard of a wire or a breaker "rattling". The freon lines
on some units can be noisy and that might be what you hear.

You can check for 240vac at the unit. It should be easy to trace to
the contactor (a big relay). The contactor is a 24vac activated relay
that supplies 240vac to the entire unit. The inside half sends the
24vac. It is possible to manually activate a contactor by pushing it
down carefully with something. The compressor and it's fan are both
activated by the contactor. If there are any additional controls such
as the startup delay board they will most likely be on the 24vac
side. Both the compressor and the fan will use run capacitors but
they may be combined in a single can. Ther may also be a start
capacitor on the compressor. Since nothing is running I doubt it's a
capacitor.

It's not unusual for wires to move or rattle inside a conduit even if
the wire is properly sized for the load. The starting current of an AC
compressor can easily be several time the run current of the whole
unit.
Wires can and will dance under the right set of circumstances.

TDD- Hide quoted text -

- Show quoted text -

You're an idiot. Wires do not move in this example.

I only have four decades experience in the field and I see it all
the time. In an industrial environment I've come across it a lot
where there are a numerous high current starting loads for motors.
The wire can actually change length under heavy load. I've seen
insulation rubbed of a wire because of this movement. The OP can
hear the #10 wires jump inside the conduit when his AC unit stars.
When you get your PhD in know-it-allogy, come back and call me names.

TDD- Hide quoted text -

- Show quoted text -

Go ahead give us the science behind it then?

High current -- wires heat -- heat causes expansion -- expansion
causes movement (not exactly "rattle" perhaps, but insulation sliding
against insulation could probably approximate a squeak)

Am I missing something? What's so hard to understand?

The inductive kick of a high current motor/compressor start can cause
wire inside a metal conduit to make noise. I've heard the telltale
racket a million times in many different settings. It sounds a lot
like somebody shaking a metal fish tape inside an empty conduit.

TDD