hvac motor current draw

hvac motor current draw
Posted: Fri Jul 10, 2009 9:24:45 AM

I have a  2004K.W. T800 daycab w a C-12 cat, my question is:the blower motor has been repl. twice witrh a dual shaft bergstrom motor and I still open the circiut breaker(30amp) if I run it on high speed..the low speed draws 7.9amps/med speed 11.7amps/ high speed 22.9 amps and the 30 amp breaker gets HOT and opens till cooled off I have hooked the blower motor up to my battery charger and used the breaker and still have the same problem, I have replaced the breaker,the relay checked the connections on the resistor card mounted on the passenger side behind the dash,I was told that paccar sends pwr. to the fan directly and grounds back through the speed sel switch, also I have reversed the squirrel cages around and it only draws 15.6 amps on high and breaker holds,but with redeced air flow to the cab.dont know what else to check any ideas would be appreciated.  thank you   daniel

RE:hvac motor current draw
Posted: Fri Aug 7, 2009 3:48:43 PM

popular mechanics did a article recently on blower motors and recomends replacing both the transistor and blower at the same time.a bad transistor can shorten the life of a blower.I had too replace a blower on a jeep and blower did not work right until i replaced the transistor too.......good luck