Who sang i want to know what love is on modern family?
No context provided
What character sang I want to know what love is on Modern Family?
Harold Grossman
No context provided
What actor sang I want to know what love is on Modern Family?
Rick Cowling
A Fair to Remember (Modern Family)
https://en.wikipedia.org/wiki/A%20Fair%20to%20Remember%20%28Modern%20Family%29
Phil manages to keep Claire at the fair till the time that he would get on stage and sing for her, but his surprise is ruined when their pharmacist, Harold Grossman (Rick Cowling), gets on stage right before Phil is supposed to get and sings amazingly. 
A Fair to Remember (Modern Family)
On Modern Family, Harold Grossman, played by actor Rick Cowling, sang "I Want to Know What Love is."