I have a new Salem travel trailer with Dometic products. Everything appears to work fine, but when I run my furnace and it turns on, my fan blows from my AC unit. I have owned 2 other RV's but have not had this problem. When the furnace shuts off due to temperature being met, my fan continues to blow and does not shut off. Does this sound like there is something wired incorrectly?

Not wired wrong..if furnace runs through thermostat..make sure fan is in auto position.. fan being on low ,med or high.then fan will run

Yes it sure does sound like something may be wired wrong, Could you please reply with model number of your AC unit as well as thermostat model? To find your AC unit model number if you don't already have it, remove your ceiling air filter assembly, and it should be on the base of the roof unit, facing you.
The base of the roof (upper) unit will have a model and serial number, and if you see a control box where all the wiring attaches as well, get model number from that too if you will. Those numbers should make it easier to determine exactly where the problem is. Thanks.