View Single Post
  #5   Report Post  
Posted to alt.home.repair
Bob
 
Posts: n/a
Default Heat pump defrost control board and thermostat reversing valve voltage level

The supply temperature of an air to air heat pump will feel cold because
it's lower than your body temperature. He has no back up heat, so the air
never feels warm. In a typical tract home where the builder hired the low
bid HVAC contractor, the duct work may be too small, so the velocity of air
coming out feels even colder because of a wind chill effect on the body.

"Dr. Hardcrab" wrote in message
news:2qPEf.70$0i1.22@trnddc04...

"Bob" wrote in message
...
A heat pump blowing cold air 24/7 does not mean it isn't working

properly.
It has nothing to do with the low voltage circuit.


Now bob, now *I* don't understand that one.....

'Splain, Lucy!



wrote in message
.. .

(Sent here from alt.hvac)

Does a heat pump's defrost control board change the voltage level
seen at the thermostat on the reversing valve lead?

When in heat mode but blowing cold air, the reversing valve
voltage at the thermostat is 0V as opposed to 26.6V when
working properly.

My heat pump puts out very good heat but it also seems to love to
periodically blow cold *far* more often and for *far* longer than I'd
expect to be due only to the defrost cycle. (The unit does not
have resistive heater strips).
Sometimes it seems to get "stuck" blowing cold for hours and sometimes

it
blows cold at least 50% of the time.

I'm trying to determine if the thermostat or the defrost control board
has gone insane.

A tech came out recently and could find nothing wrong with the heat

pump.
The refigerant level was perfect and its diagnostic board reported no
problems. It is a trane.
It was of course not misbehaving when he was here.

This is Arizona and therefore only about 50F with low humidity.

Also, the heat pump, during summer months, sometimes does the
opposite. It will blow hot air when it should be blowing cold.

Thanks in advance for any help.