Vintage 1950s Lennie Lennox Heating & Air Conditioning Advertising Hardboard Sign. This is a very hard to find item. Through all my research I was not able to find anything like it. Features 3 different company advertisements. Cronstroms is a heating and air conditioning company in Minneapolis which was founded in 1926. I wasn’t able to get much info on the Fritz Brothers but I can see FRITZ BROTHERS was handpainted on probably using stencils. Measures 29″x 20″. Please see photos and if you have any questions feel free to ask.