Trane central air unit quit doing its thing (recently made another
post about it) and I finally cracked open the housing.
Here are some pics - front and rear of a capacitor and a pano of the
electronics. Am I mistaken or is the cap leaking stuff out that it's
not supposed to be leaking? If so, under what heading in the yellow
pages should I be looking for replacement pieces?
Anything else you see that stands out as being obviously bad or
suspicious? I can take closeups of anything you want a better look at.
Thanks for all input.
5/370 should be the cap for the fan. Looks like the
terminals are pretty badly rusted. GE had a bunch of bad
caps. I'd be wanting to test that one for farads, and then
replace it regardless of the reading.
I notice you have a big round cap (can't tell if it's double
value, but at the moment it doesn't look like it) to the
You likely won't find replacement AC caps sold at retail.
Might try "capacitors" in the yellow pages.
Actually the big horizontal fan at the top runs, the basic problem is
the compressor isn't engaging. First noticed due to no "quish-quish-
gurgle" in the freon line inside going into the air handler as should
be happening. A few months ago when it was last fired up it was doing
I did find a couple of dessicated dead lizards hung up in the
How do you know it's the cap? You have to start with the basics first.
When you turn down your t-stat to turn on the A/C, the contactor
should click closed. If it doesn't, you have to look at that first.
With the power on and the thermostat set for cooling, get a volt meter
and check across the two bottom screw connections on the contactor ( the
brown and the red wires). If you are reading voltage, the contactor is
bad. There should be "0" volts across those two if the contacts are
closed. The set of contacts on the top of the contactor control just the
fan motor on that particular unit. (some of the older Tranes are wired a
little screwy) Larry
On May 3, 11:57 pm, email@example.com (Lp1331 1p1331) wrote:
My thoughs exactly. The contactor usually has 2 seperate terminals,
one for the fan and one for the compressor, so its possible for one
component to work and not the other.
If everything checks out, you could be low on freon, which will
prevent the compressor from turning on. To check, you can bypass the
high pressure switch for a few seconds to see if the compressor comes
How do I identify the high pressure switch and how does one bypass it?
Here's what I've found so far. The spade connector contacts on both
the capacitors were highly corroded. I used a Dremel to grind off rust
to get a clean contact surface.
The electromagnetic contact switch works, definitely engages. I hooked
everything back up, put the top of the unit back on secured it with a
few of the screws.
The top fan works so apparently that capacitor isn't bad enough to
prevent that. As I was sitting by the unit after a few minutes I heard
a humming noise that sounded like the compressor had momentarily
kicked in but then stopped.
Further, on that circuit board there's a red LED that flashes while
the unit is running.
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