When I run the AC it smells like a crayon is melting. Any idea why?

There are many possible causes for odors from your vehicle's climate control system. The first thing to check is if the cabin air filter has been changed at proper intervals and to make sure you continue to change the filter on a regular scheduled basis. This filter catches pollen, dust, and other particulate debris that is in the air as it circulates through the climate control system. If the filter has been allowed to become over-saturated with debris, mold, mildew and other nasty stuff can form and spread throughout the duct-work of the entire system. If this has happened, then a service will need to be performed to clean the internal duct work of the climate control system. Obviously, there can be other external causes for your odor, such as something under the hood of the vehicle causing the odor and the odor transferring to the interior of the vehicle. Our shop would be happy to diagnose your vehicle to determine the exact cause of the odor and recommend the correct repair.