Re: Odd new record high ambient temp behavior, Trane XR12

Many outdoor units have a high limit switch, that helps
protect the equipment. Some high limit switches sense excess
temperature, and some sense excess pressure in the discharge
line. Trane probably has both.

Sounds like your unit is "tripping off" at exactly the time
when it's needed the most. I'd suggest to have the outdoor
unit professionally cleaned. Dirty fins hold the heat in.
Even coils that look clean, often can benefit from the
cleaning chemicals. I've done this more than a couple times,
clean looking coils can have enough dirt to screw up the
performance.

Depending on who did the service, and what's his training
and attitude, you might also have too much freon in the
system, whic will also help to trip off with high pressure
switch.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"John Tessler" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
I have a 7 year old 3 ton Trane XR12 heat pump unit (2-stage
heat, 1 cool)
servicing a 1500 sq ft single story house in North Texas.
The outside
compressor is located in a western alley where it gets
direct sun about
2:00 pm for a couple hours but is otherwise shaded by my/my
neighbors
houses.

I like my AC cold, and have run this unit at 70 F for the
past 7 years
without a hitch. The one air filter is changed monthly, anf
the outside
coils are clean. Sight glass shows everything clear. The
unit has performed
flawlessly, like a champ.

Recently, though, corresponding with some record high
temperatures

07-31 105
08-01 108
08-02 110
08-03 111
08-04 109
08-05 107
08-06 106
08-07 106

beginning about the time the sun hits the outside
unit/and/or the outside
temp hits 101-102 the unit stops produding cold air. Up
until that point,
works perfectly, hits set point 70 with no problem. Just
updated thermostat
to Honeywell 7-day, same behavior, that is, later in the
evening, about
8m or so, when the outside temp drops down below 100, the
cold air starts
up again and the house cools down as set on the thermostat.
Ice cold, so
freon seems good. Rinse and repeat with each 102-3+ F day so
far.

Is the unit, which outside of these extremes seems to work
flawlessly/no
differently than last 7 years, protecting itself somehow
with some type of
automatic limiting switch? Or is this indicative of some
breakdown that
would require technician service?

Thanks for any insights. In the meantime, I'm warm now, I'll
be cool
tonight and tomorrow morning, and mid afternoon forward
tomorrow I'll be
warm again, unless something changes.