Ok I believe that a transformer changes voltage from x to y, either
raising or lowering the voltage as required for the application. For
example, the a/c charger for my phone lowers the voltage, and an
inverter (like to power my laptop in my car) would raise it. If I am
wrong please set me straight.
Now to the big questions . . .
Is there a transformer located in the condenser (outside part) of a
central air conditioning system.
Is there a condenser unit manufactured in the last 15 year that
requires replacement of the condenser if the transformer fails, as
opposed to just replacing the transformer itself.
I am asking because my friend was told her condenser needed
replacement because the transformer was bad. Yes she did have it
replaced. I am asking because this sounds "suspicious" to me. I
imagine that it should be relatively easy to procure a replacement
transformer and install it, instead of replacing the whole condenser.
She has gone to sleep so I do not have specific brand or type info
except that it is what most people would call "central air" in a home
about 15 years old.
I am by no means an expert so hopefully more knowledgeable people can
Thanks in advance,
On Sat, 12 Jul 2008 22:13:20 -0700 (PDT), firstname.lastname@example.org
You may believe that, but home repair is not built on faith.
An inverter changes DC to AC. Another part of the circuit might
change the AC voltage.
Do you mean the entire condensor box with everything inside? That's 2
feet cubed or so?
Or is there any chance your talking about the capacitor (which in
radio is often called a condenser)? Which is about 8" by 4 inches,
usually with 3 wire connectors on one end.
But you mean the entire box or you wouldn't be posting, right?
I don't think there are any transformers in the condenser cabinet, in
any unit I've seen.
OBSOLETE paragraph: Isn't there a wiring diagram on the inside of the
cover panel? Or maybe a manual folded and stuffed in the cabinet
under that panel? Oh, I was thinking the other meaning of condensor,
and her outside unit has been replaced by now.
I have only experience with oil and gas heat with electric AC, and
there's a small transformer inside the house, in the furnace, that
provides 24 volts for the control circuit (thermostat, furnace relay,
Most failures are "opens" and that woudln't damage anythign, and even
if the voltage were too high, it wouldn't damage the whole outside
unit because it only powers the solenoid in the outside unit. It
woldn't even hurt that.
However condenser units do fail sometimes of course. Why did she
call a repairman in the first place? How old was the system? Did it
work at all?
I am an amateur too. And might be wrong in almost anything I say.
Friends of mine are selling their home and they had a guy who fixed up
another home for sale (and did a good job according to the friends of
my friends who first hired him) come over, and one of the things he
said was that they needed interconnected smoke alarms in every bedroom
to comply with code, and that he could get wireless ones so they
didn't have to run wires.
Turns out, they only need one battery powered smoke alarm on their
first floor and one in the basement (no other floors) People do lie,
We are in different cities (5 hours away). I wasn't there, and she
wouldn't have a clue about a manual.
From our conversations it sounds like the entire outside unit was
replaced. We also talked about making sure both the interior and
exterior units matched in tonnage
Ok that akes sense.
Problem was no cold air from the system, blower worked. About 15 yo
worked since she bought the house in May.
Sound as if you are a better amateur than I
That last line is my concern, of course.
There may be some semantic/communication confusion with the fault
described but if indeed the only fault with the unit was a transformer
then it could have been replaced as a component. I would perhaps re
examine the information you have received, then again there are many
sharks around in the service industry who seem to home on on female
On Jul 13, 2:16 am, email@example.com wrote:
I wouldn't call that a lie. That is required by current code for new
construction, but not necessarily if one is selling an existing
structure. Remodeling, well, that is a grey area likely depending on
the extent of the remodeling, and the interpretation of the AHJ.
As a relatively new HVAC tech, I've installed equipment for a couple years,
and trying to get started as a service tech. I've mostly worked on central
AC, where the heat is natural gas, or oil. Serviced very, very few heat
That said, I've never seen a transformer in the outdoor unit. And
transformers are easily replaced. There is typically a transformer in the
furnace. The thermostat calls for cold, and the circuit board sends a 24
volt signal out the small wire, to the outside unit. This low power signal
activates a contactor, which connects the 220 volt power to the outdoor
It sounds like there is a communication error going on, here. It's possible
she remembered the wrong word (transformer, instead of compressor or
contactor) or that the guys on the job were less than honest with her.
I think the tech turned his meaning around. What he thought was: "I want to
replace the condensing unit, so let's claim "X" is bad."
The outside condensing unit is made up of several components: Compressor,
coil, tubing, dryer, electronics, wiring, fuses, etc. None of these
components is a "transformer."
The only possibility that comes to mind is the "transformer" on the utility
pole. If the light company's equipment went really bad, it is conceivable
that fatal damage could be done to the outside condensing unit. If that was
the case, the utility company would cheerfully pay for any damage.
Sounds most likely to be a scam artist. There is typically no transformer in
the outdoor unit, and should there be one.....certainly replacing it, rather
than the entire condensing unit, makes much better sense.
It is fair to offer the opinion that a 15 year old condensing unit may
indeed need replacement, and the choice of descriptions given by the repair
guy as interpreted by your friend may have become a bit confused in the
I certainly does sound extremely suspicious as you describe the situation.
Lots of good advice in other posts. In short, there is at least one
transformer in the AC system and it is commonly in the indoor unit. It can
be in the outside unit and there can be one in each unit. You can hold it in
the palm of your hand. It is a common failure item, can be replaced easily,
and is inexpensive. A complete outside (condensing) unit should not be
replaced if only a transformer is bad.
It is a different story if the bad part is a "compressor".
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