Hi rkymthi,
Welcome to the Heartland Owners Forum. There's lots of useful information here along with a great bunch of friendly and helpful people.
If the furnace blower doesn't start, it won't allow the gas valve to open to light the furnace. The blower has to get up to 75% of normal speed to trigger what's call the sail switch. After that, the furnace will try to light.
When the thermostat calls for heat, it signals a relay to turn on the furnace blower and signal the furnace control board that heat is needed. You should hear a click, probably overhead near the air conditioner air return. If you don't hear a click, either the relay is bad, or it's not getting the signal from the thermostat.
Low battery voltage could be responsible, but presumably the service center was able to run the furnace successfully while connected to shore power. You should also be able to.
Suburban Furnaces usually have a 2 year warranty from Suburban. Even if you're just over the 2 year mark, Suburban customer service might still cover another service call since you had the earlier service call.
We have an owner-written heating and cooling guide that has some additional information you might find helpful.
Here's a link.