Smelled Coolant when using AC

[mwiadro]

04' Cayenne S.  Current mileage 121,000.  Coolant pipes were repaired by indie shop at 90K miles - about 2.5 years ago.  

 

During trip to DC (70miles), smelled coolant coming through AC vents.  Temp gauge never moved.  No warning lights.  There was no evidence of coolant on ground when parked.  After return trip, checked coolant level:  level had dropped from max to min level.  (no sign of coolant on garage floor, but smelled coolant burn off).  Also, was surprised the radiator fan did not kick in and run given the hot conditions, stop and go traffic, etc.

 

Suggestions on where to look for leak(s) welcome!  

 

Michael 

[mihaipopa]

I would check the coolant reservoir, if you still have the original. It's usually the next thing to go, after the pipes. It develops small fissures around the bottom seams that let coolant leak slowly when pressuriezed, hence the lack of evidence on the garage floor.

[RFM]

If you smell coolant through the AC vents there is a high probability that the heater core is leaking which is centrally located under the dash. The heater core is not equipped with a control valve, but by an air flap, there flows continuously coolant under pressure through the core, hot or cold, AC on or off will remain the same. Traces of coolant should be present in the condensed water under the car after driving with AC on. 

[Scott C]

An easy way to test for a heater core leak is to move the air output to the windshield (defroster) position and turn on the heater.  If the core is leaking coolant will fog the windshield.