The U.S. Federal Trade Commission (FTC) is attempting to get to the bottom of an age-old problem — why it seems like McDonald's ice cream machines are never working. 

The Wall Street Journal reports that the agency has launched an investigation into the problem, which has become synonymous with the fast-food chain for years. The FTC sent letters to McDonald's owners, asking for details on reported issues with their ice cream machines.

While the chain restaurant placed blame on costly repairs and technical malfunctions, the manufacturer said that's not true. Taylor Commercial Foodservice LLC said the misinformation stems from a "lack of knowledge about the equipment and how they operate in the restaurants."

“[When working with dairy products] you have to make sure the machine is cleaned properly. The machines are built up with a lot of interconnecting parts that have to operate in a complex environment and manner,” a representative for the company said.

The ice cream machines are primarily used to create soft-serve cones, milkshakes and their signature McFlurry. However, customers have taken issue with the machines routinely being out of service, as well as with being unable to purchase their requested items.