Ask the Beaverton Car Guy: Mysterious smell and liquid coming out of my defrost vents

By Larry “The Car Guy“ Ferguson

Riccardo is a server at a restaurant my wife and I frequent here in Beaverton. He called me recently saying he had a strange smell coming from the vent of his older Domestic vehicle when he turned on the defroster. Riccardo mentioned that when warming up his vehicle after his evening shift, he had a horrible smell coming from his defrost vents at the very front of his dash board, and as the vehicle’s engine warmed up, the smell would get stronger.

Strange smell and liquid

Riccardo also mentioned after the smell had become present for about two weeks, the windshield would begin to fog up as the engine was warming up. After this went on for about three weeks, one evening after work while the engine was warming up, Riccardo noticed that there was actual liquid being sprayed out of the defrost vents and onto the inside of the windshield. It was also dripping onto the passenger side floor board! He knew it must be serious so he gave me a call.

Heater core

I informed Riccardo that it has been my experience that this is a sign that the vehicles heater core has gone bad and was leaking coolant into the heater-box inside the dash board. This happens when the heater-defroster is turned on even though heater core has failed.

What happens is the coolant that circulates through the heater core which provides heat for the interior cabin of the vehicle, begins to leak into the heater box, and the air which circulates around it to provide the heat for the cabin area, picks up the foul odor of the anti-freeze/coolant.

In the event the heater fan is on a high setting, the fan motor can actually push the coolant/Antifreeze out of the heater box, out the vent and up onto the windshield.

Happy ending

Riccardo came over to my office and after performing a pressure test on his cooling system, sure enough it was the heater core and not just a simple heater hose.

Riccardo didn’t have a lot of funds for this repair, so I helped make some calls for estimates. Within an hour, we had an appointment at a local Beaverton shop that would do the repair at a price that Riccardo could afford.

Thank you all for reading, and again if there are any questions or advice I can offer I am just a phone call or email away.

Larry’s specialty is locating cars, even hard to find cars, for everyday folk. He has been in the automotive industry for over 35 years and has several degrees in automotive technology. Email him at or call 503-930-1493