“It stinks. I turn on the air conditioning and you could pass out from the smell.” Heard that complaint before? Sure you have, and if you’re an import specialist, you may hear it more often than techs in domestic repair shops. However, the simple truth is that the odor problem afflicts all makes. The odor is caused by a buildup of a fungus on the evaporator core. That fungus is related to the kinds of fungus that cause athlete’s foot and jock odor. The odor typically lasts for the first few minutes of A/C operation, but that’s enough to bring the customer in.