Carrier 50TJQ012 heat pump

[boat racer]

can anyone explain to me how the defrost control board works on these? Looks essentially the same as the more recent 50TFQ

both are a mystery to me

[Hrdworkingacguy]

from the 50tfq manual...

"DEFROST (Sizes 004-007) — As frost builds up on the outdoor
coil, the coil temperature drops below 28 F. When this
outdoor-coil temperature drop is sensed by the defrost thermostat
(DFT) and the defrost timer is at the end of a timed period
(adjustable at 30, 50, or 90 minutes), the unit operates in a
defrost cycle controlled by the defrost timer and thermostat.
During this cycle, the reversing valve solenoid (RVS) is
energized and the outdoor fan shuts off. The electric heaters (if
installed) will be energized.
The unit continues to defrost until the coil temperature as
measured by DFT reaches 65 F, or the duration of defrost cycle
completes a 10-minute period.
At the end of the defrost cycle, the electric heaters (if
installed) and the reversing valve will be deenergized, and the
outdoor-fan motor will be energized. The unit will now operate
in the Heating mode.
If the thermostat is satisfied during a defrost cycle, the unit
will continue in the Defrost mode until the time or temperature
constraints are satisfied.
DEFROST (Sizes 008-012) — When the temperature of the
outdoor coil drops below 28 F as sensed by the defrost thermostat
(DFT2) and the defrost timer is at the end of a timed period
(adjustable at 30, 50, or 90 minutes), reversing valve solenoids
(RVS1 and RVS2) are energized and the OFC is deenergized.
This switches the position of the reversing valves and shuts
off the outdoor fan. The electric heaters (if installed) will be
energized.
The unit continues to defrost until the coil temperature as
measured by DFT2 reaches 65 F, or the duration of defrost
cycle completes a 10-minute period.
During the Defrost mode, if circuit 1 defrosts first, RVS1
will oscillate between Heating and Cooling modes until the
Defrost mode is complete.
At the end of the defrost cycle, the electric heaters (if
installed) will be deenergized; the reversing valves switch and
the outdoor-fan motor will be energized. The unit will now
operate in the Heating mode.
If the space thermostat is satisfied during a defrost cycle, the
unit will continue in the Defrost mode until the time or temperature
constraints are satisfied."

:eek:

[boat racer]

Thanks for taking the time to type all that out. It will be very helpful to me today

[Hrdworkingacguy]

Cut/paste FTW!!!! :eek:

[timebuilder]

...and you can get your very own pdf copy by going to the Carrier website and searching for literature under "commercial."

[boat racer]

...and you can get your very own pdf copy by going to the Carrier website and searching for literature under "commercial."

Tried that and could not get anything to come up even when I shortened it to "50"

[timebuilder]

http://www.docs.hvacpartners.com/idc/groups/public/documents/techlit/50tjq-1w.pdf

[boat racer]

;)