Blower fan won’t come on in “auto” mode but will in “on”

I have a Honeywell model number NHGK076AF01 propane furnace. It is about 15 years old. The problem started when I noticed the breaker had tripped and I had no heat. After resetting breaker, I tried again. Everything goes as it should except when time for blower fan to come on. It doesn’t come on if in “auto” mode but if I put it in the “on” mode, the blower comes on and I have heat.

I replaced the limit switch L170-40 and still have the same problem. There is another limit switch in the blower area L140-40. I checked this one with ohm tester and it seemed OK – it was closed tester beeped. I am scared to let it run too long – two minutes maybe – and when the blower doesn’t come on, I set to “on”. Another thing is I’m not sure if it would trip the breaker again if I didn’t turn the blower on instead of limit switch turning everything off. I’m not sure what else to try. Funny the blower works in “on” position and not “auto”. Thank you for taking the time to read.