On Thursday, November 28, 2019 at 8:11:12 PM UTC-5, trader_4 wrote:
On Thursday, November 28, 2019 at 12:28:16 PM UTC-5, Ralph Mowery wrote:
I have a Trane heatpump that is about 12 years old. In the summer it
cools fine.
Last winter the house was about 2 deg cooler than the thermostat was
set for. Noticed the inside air handler was running,but the outside
unit was not.

Checked and had power. The relay that puts power to the compressor and
fan was not pulled in. The coil did not have any voltage on it. The
circuit board has a led that blinks once per second like the paper in
the pump says it should if everything is ok.

I cut it off by the thermostat and then 5 minuits later turned it on.
Everything is working fine now. The heatpump did that to be about 3 or
4 times last year. I don't recall the temperature then,but today it was
about 40 deg F outside. It was 66 inside instead of 68 like it was set
for.

I don't mind calling a man for service, but there would not be anything
I know of for him to find. Any ideas on why the outside unit will not
cycle off and on like it should ?
Maybe it goes into the defrost mode and gets hung up ?

IDK how heat pump systems call for heat. Is there one wire that says
make heat, another one that turns the blower on? Or does one wire say
make heat and the system turns the blower on? If it's the latter,
then since the blower is running you can rule out the thermostat.
If it's two wires, then it's possible it's a thermostat problem.

I agree that calling for service on something like this is really bad.
They won't see it happening and even if they do, probably won't have
any more idea what to do that you do.

Another question, what does it do when it's 66/68 and you just leave it?
Does it eventually come on? Does it go back on when it drops to 65?, etc.
Or does the compressor just stay off indefinitely? What was it doing just
before, was it maintaining 68? If so, then you'd think it must stay off
a long time when it's 40 outside for inside to drop two degrees.