In 1989, his wife Tudi convinced him that they should move to Los Angeles. He found a place for them to live by managing an apartment complex, and catered events at a Jewish synagogue on the side. After receiving a traffic citation, Karn attended a traffic school and sat beside an agent who told him about casting for the new television show called Home Improvement. The role of Al Borland had already been given to Stephen Tobolowsky, but when taping was scheduled, Tobolowsky was busy with another movie and the role had to be recast. Karn was a guest star in the pilot episode but became a regular cast member when the show was picked up by the network.