here's an issue i am trying to figure out as it all doesnt make sense to me. my hvac (heater & air handler in attic) keeps blowing edison fuse every few months. couple of years ago the control board fried, had ac guy come replace it, he said the motor might be on its way out. this time around i was digging in myself to see what the heck was going on. 1st was to measure the current in this York unit, with my General Instruments clamp meter i got the inrush and running amps. 30A inrush and then 14.8A running. these #'s match up to the two motors in the unit (an inducer for heat, and a 1hp blower motor). the motor is rated 1hp @ 14A 120v 60Hz. thats crappy efficiency, but nonetheless all the #'s seem to be on par with labels and what i measured.
the unit is fed via 10/2 romex to a Bussmann fuse socket.
ok, so i start looking and notice the Bussmann edison fuse socket with outlet is rated just 15A, the hvac unit has a 8ft 14awg cord/plug. doesnt seem so good for 14.8A running unit. i looked around inside the unit doors and found a few burnt wires at the crimp connectors (its all MIC stuff). i replaced the edison socket with a Eaton fused hvac disconnect, did hardwire using 12/2 cord (from disconnect directly to the control board, no wire nuts except for the gnd wire). i replaced the burnt wires (which were only 18awg) with some of the 12awg from leftover cord. cleaned connections, etc etc. everything went back and when the call for blower came on it just didnt go, about 0.2sec of starting and then quit. turns out two pins of relays basically vaporized.
ok, so, i look at the board and note the path of the switched 120vac (see pic). oddly the fan blower is connected on the 10A relay side. this i just cant figure why. the motor is rated 14A, so why does it connect to a 10A relay?
the burnt wires were a line-in wire, and a neutral wire to blower motor. burnt so bad i suspect they were restricting current during startup, and now that i fixed all that the current was allowed to move and the pins on the board fried off.
i am wondering if they wave solder these board but if the solder time is low due to the small parts i am wondering if just not enough solder to wick onto the larger pins? to me the board design and wiring is just poor.......
here's the pic (path of 120vac across the relays to motor)
1 is the 30A relay contacts (SPST NO)
2 is the 10A relay (SPST NO)
3 is (WTF) a hair thin jumper, about the size of the wire on 1/4w resistor
4 is the terminal to motor hot
the PCB trace that is on the 30A pin burn, that goes to a "EAC" terminal, so wondering if i should connect motor here since its handled by the 30A relay.
i am attempting to fix this board, new relays from Mouser just $5. a new board will be around $100 !!
the unit is fed via 10/2 romex to a Bussmann fuse socket.
ok, so i start looking and notice the Bussmann edison fuse socket with outlet is rated just 15A, the hvac unit has a 8ft 14awg cord/plug. doesnt seem so good for 14.8A running unit. i looked around inside the unit doors and found a few burnt wires at the crimp connectors (its all MIC stuff). i replaced the edison socket with a Eaton fused hvac disconnect, did hardwire using 12/2 cord (from disconnect directly to the control board, no wire nuts except for the gnd wire). i replaced the burnt wires (which were only 18awg) with some of the 12awg from leftover cord. cleaned connections, etc etc. everything went back and when the call for blower came on it just didnt go, about 0.2sec of starting and then quit. turns out two pins of relays basically vaporized.
ok, so, i look at the board and note the path of the switched 120vac (see pic). oddly the fan blower is connected on the 10A relay side. this i just cant figure why. the motor is rated 14A, so why does it connect to a 10A relay?
the burnt wires were a line-in wire, and a neutral wire to blower motor. burnt so bad i suspect they were restricting current during startup, and now that i fixed all that the current was allowed to move and the pins on the board fried off.
i am wondering if they wave solder these board but if the solder time is low due to the small parts i am wondering if just not enough solder to wick onto the larger pins? to me the board design and wiring is just poor.......
here's the pic (path of 120vac across the relays to motor)
1 is the 30A relay contacts (SPST NO)
2 is the 10A relay (SPST NO)
3 is (WTF) a hair thin jumper, about the size of the wire on 1/4w resistor
4 is the terminal to motor hot
the PCB trace that is on the 30A pin burn, that goes to a "EAC" terminal, so wondering if i should connect motor here since its handled by the 30A relay.
i am attempting to fix this board, new relays from Mouser just $5. a new board will be around $100 !!
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