This summer I was running the a/c and one day it tripped the breaker. I checked the thermostat and the a/c unit itself but both seemed fine. It trips the breaker as soon as it starts to blow the air out. Now when I run the heat it does the same thing except now it gives me a code to check the limit switch. Could the limit switch cause the breaker to trip? I tried removing the filter in case it wasn't getting good air flow. And I checked the breaker. It's a 1998 lennox furnace/ac. Any suggestions?