21
6) BKP
TM
runs but does not dehumidify.
Follow the procedure in (4) "unit runs a short time then locks out" to observe sight glass while running the
BKP
TM
. Using thermometers and hygrometers, take the dry bulb temperature and relative humidity
readings at the air inlet to the BKP
TM
.
Possible Cause
Solution
High and low pressure gauges did not move when
the unit comes on.
Check compressor wiring, and capacitor. If compressor
is hot, allow to cool. OHM compressor to determine
winding condition. Replace compressor
If the compressor runs, but low pressure reads too
high and high pressure reads too low.
Check if the hot gas bypass is leaking by. Check if the
Reversing valve is leaking by. If both of these are OK,
replace compressor.
If the compressor runs, but both low and high
pressure reads low
Check if the evaporator coil is frosted up. If frost is
present, allow the frost to melt completely. Check hot
gas bypass
If pressures are still low, and there are bubbles in
the sight glass, the unit may have a refrigerant
leak.
Check for leak, recover refrigerant, repair leak, replace
filter dryer, evacuate and weigh in proper change.
If pressures are still low and there are no bubbles
in sigh glass.
Replace thermal valve and filter dryer.
If high press reads high and low pressure is ok or
high.
Check airflow through the unit. If it is low, check filter
and ductwork. External static should not exceed 0.5“
Check that air inlet temperatures are not too hot or too
humid.
For AC units, if a hissing noise can be herd from
the reversing valve, feel the check valve on the
small tube from the center port.
If the check valve is hot while running then the reversing
valve is leaking. Shift the unit from heating to cooling
several times and then retest. If it is still hot, replace the
reversing valve.
If no problems are found, unit may be overcharged. Recover refrigerant. Evacuate and weigh in proper
charge.
For BKP-AC
TM
7) BKP-AC
TM
runs in either dehumidification or cooling mode only but does not change mode
(reversing valve does not shift).
Remove the cover from the thermostat. Turn the temperature setting all the way up then all the way
down. Observe the mercury in the glass bulb. If the mercury does not move from one end of the bulb to
the other, replace the thermostat. If the bulb does not “rock over” at the current temperature, replace the
thermostat.
Remove either wire from the time delay to keep the
compressor from starting. With the thermostat all the
way down, check for 24 V at the reversing valve coil.
Do not run the BKP
TM
compressor without a cover.
If yes, then the reversing valve coil or the valve
itself is bad.
If no, check the wiring to the thermostat and to the
BKP
If you have voltage to the reversing valve coil, have
someone turn the thermostat up and down as you listen
for a definite "click" in the reversing valve.
If The valve clicks but does not shift, replace the
reversing valve
If the valve does not click replace the solenoid coil.
Summary of Contents for BKP 250
Page 12: ...12 BKP 250 350 450 and AC Wiring Schematic ...
Page 13: ...13 BKP 250 350 450 Wiring Diagram ...
Page 14: ...14 BKP 250AC 350AC 450AC Wiring Diagram ...
Page 15: ...15 BKP 250AC 350AC 450AC With Cooling Priority Wiring Schematic ...
Page 16: ...16 BKP 250AC 350AC 450AC With Cooling Priority Wiring Diagram ...
Page 17: ...17 BKP 250AC 350AC 450AC Remote Condenser Wiring Diagram ...
