When a parallel circuit becomes a series circuit ... Hmmmm
Model
ED27DQX series
Uses Adaptive Defrost Control, p/n 216926
Symptoms
Very poor cooling
if thermostat OFF:
compressor OFF, as expected=> good
condenser fan OFF, as expected=> good
evaporator fan ON! Huh? -----> they're all wired in parallel!! How can this be true???
if thermostat set for ANY cooling setting
compressor ON, as expected=> good
condenser fan ON, as expected=> good
evaporator fan OFF! -----> Huh? they're all wired in parallel!! How can this be true???
ANALYSIS
The defrost heater and the evaporator fan return path share a crimp connection going into the wiring harness connector on the neutral side. The connector pin has oxidized and created on open circuit condition between the two sides of the wiring harness connector. This changes the circuit, which normally has the evaporator fan in parallel with the condenser fan and compressor motor, such that the evaporator fan is now in series with the defrost heater and compressor//condenser fan motors. The resistance of the compressor motor and defrost heater is much lower than that of the evaporator fan. The result is that the evaporator fan runs when in defrost mode, but not in cooling mode!! Ahaah!
