Breaker tripping

I have 2 5000 BTU units and an 8000 BTU unit running which all are going to the lights breaker that’s a single pole double 15 amp breaker. The breaker trips when the temperature outside is above 80 degrees. So I have a question. Can I use an ac extension cord that’s 12 or 15 foot for the 8000 BTU unit to plug into the washing machine outlet as the washing machine is on a different breaker that’s a single pole 20 amp breaker.