im_dragon
29-10-2009, 12:40 AM
My Amana SRD25S5W stopped cooling a couple of months ago. Armed with component specs, schematic and wiring diagram, I spent the last month trouble-shooting it on and off, with countless hours learning about refrigeration systems from the Internet. Here's what it comes down to:
The compressor windings resistance, and ground isolation all check out. The evap fan, condenser fan, overload ckt breaker, run capacitor, adaptive defrost control board, adaptive defrost, all work properly. The condenser is relatively clean. PTC relay is solid (doesn't rattle when shaked), looks new, and seems to work. It's barely warm when running with the compressor.
The compressor starts and runs fine, with or without the PTC relay connected (I removed the relay and use jumpers to bypass it). The compressor, rated at 1.6A underfull load, starts at 2-3A, then drops to 0.8A steady state. Frost starts to form on the evap coils at the entrance to the coils only. This could indicate low *****, but there's more ...
After 3-5 minutes, the frost melts while the compressor runs under full voltage (120VAC, I'm in the US), with the current drops to 0.5A. The fridge is confirmed not in defrost cycle, as the defrost heater is cold, and compressor is still running.
Occasionally and randomly, the frost starts to form again at the avp coils entrance for no reason (current increases to 0.8A), then melt again after a few minutes, with the compressor never stops running from the very beginning. 120VAC measured at the C terminal of the compresor (after the overload circuit breaker) at all time.
The PTC relay for some reason does not make any difference here. The resistance checks out OK (5.6 Ohms at room temp, specs is 3-12 Ohms). I test it on the bench with a 100W light bulb. The bulb does go off after a while, once the PTC relay is warm. The resistance increases whith high current passing through, and decreases during cool down when current is removed. So PTC relay seems to function OK.
The compressor runs cool to the touch with normal sound that I hear from those of other fridges, again, with or without the PTC relay. This is very strange because I thought the PTC relay is needed to start the compressor. In my case, the compressor starts and runs fine with just the 15uF run cap connecting between the start windings (compressor S terminal) and L2 (AC neutral).
What could be wrong here? Thank you very much.
The compressor windings resistance, and ground isolation all check out. The evap fan, condenser fan, overload ckt breaker, run capacitor, adaptive defrost control board, adaptive defrost, all work properly. The condenser is relatively clean. PTC relay is solid (doesn't rattle when shaked), looks new, and seems to work. It's barely warm when running with the compressor.
The compressor starts and runs fine, with or without the PTC relay connected (I removed the relay and use jumpers to bypass it). The compressor, rated at 1.6A underfull load, starts at 2-3A, then drops to 0.8A steady state. Frost starts to form on the evap coils at the entrance to the coils only. This could indicate low *****, but there's more ...
After 3-5 minutes, the frost melts while the compressor runs under full voltage (120VAC, I'm in the US), with the current drops to 0.5A. The fridge is confirmed not in defrost cycle, as the defrost heater is cold, and compressor is still running.
Occasionally and randomly, the frost starts to form again at the avp coils entrance for no reason (current increases to 0.8A), then melt again after a few minutes, with the compressor never stops running from the very beginning. 120VAC measured at the C terminal of the compresor (after the overload circuit breaker) at all time.
The PTC relay for some reason does not make any difference here. The resistance checks out OK (5.6 Ohms at room temp, specs is 3-12 Ohms). I test it on the bench with a 100W light bulb. The bulb does go off after a while, once the PTC relay is warm. The resistance increases whith high current passing through, and decreases during cool down when current is removed. So PTC relay seems to function OK.
The compressor runs cool to the touch with normal sound that I hear from those of other fridges, again, with or without the PTC relay. This is very strange because I thought the PTC relay is needed to start the compressor. In my case, the compressor starts and runs fine with just the 15uF run cap connecting between the start windings (compressor S terminal) and L2 (AC neutral).
What could be wrong here? Thank you very much.