Problem (I think)
I have a 3000 S/F ranch with central A/C. The A/C is controlled by the same
thermostat as my heat.
It's the standard issue Honeywell t-stat, round with A/C and Fan switches at the
11:00 and 2:00
positions. Heres the thing thats strange. When I set the temp to say 80, the
A/C comes on but
doesn't shut off until the temps down around 70 - 72. This is according to the
thermometer on the
t-stat, as well as a digital thermometer I have on the other side of the room.
This same t-stat is
spot on in the winter months when used for heat. Why is there such a wide swing
in tempurature on
A/C but not with heat ???? When I pop the cover off the t-stat there looks to
be an adjustment
pointer on the bottom. what does this adjustment do ???? I'm stumped here.....
Thanks for the
This is Turtle.
Pull the ring cover and see if any wires are hanging up on the mercury bulb
going to the subbase. If not change the thermostat for you got a bad cooling
antipistator in the sub base and getting a long range on cooling.
1) The t-stat is out of calibration. What does the temperature rise back
up to before it calls again for cooling?
2) The t-stat may have a worn-out bimetal (that's the ribbon spring
looking thing behind the bulb assembly). No problem in heat mode
because it wasn't bad during winter.
3) Short, causing current to flow through the heat anticipator or
cooling compensator during call for cool. This will fool the t-stat into
thinking its warmer inside than it is.
This is a typical problem in older Honeywell rounds when they pass about
20 years in age. How old is this stat?
In any case the t-stat seems to be the defective component. There are
other possibilities, but most would cause erratic cycling which you
didn't report. Given that this is a common fault for this t-stat odds
are its due for replacement. HTH.
It rises back up to the set temp before it comes back on.
Whats that slide adjustment thing on the bottom of the t-stat ????
Actually, this problem started at the end of last summer but I had forgotten
about it. The heat was
ok this winter though.
Just about 20 years old............. Now i'm noticing it's 12 degrees colder
than it's set for
and the A/C is still running........ Maybe it's time for a digital
t-stat............. Are they
any good ????
That has no effect on cooling whatsoever. That's a heating element
that's inline with the heating circuit only.
It's has little numbers on it. 0.2, 0.4 etc. These are the current draw
of the 24volt heating circuit, and it should be set to match that
current. Anyway, not your present problem.
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