when air conditioner or defrost is turned on my wife says it emits a bad smell. Dealer suggested a $1200 repair estimate to fix?
Why not try spraying Lysol spray into the HVAC intake?
While we can’t smell the situation in your car, it is likely to be mold/mildew in the HVAC ducts.
Lysol spray would be a much cheaper approach than the dealer’s $1,200 solution (which may actually just involve spraying something into the ducts!)
First thing to do is check to see if the condensation drain for the AC is restricted. This will be a rubber tube pointing down towards the ground on the outside of the firewall. This can be cleared with compressed air or a length string trimmer line.
To get rid of any odors from the vent system you might try using Lysol disinfectant spray. To do this, open the hood to gain access to inlet port at the base of the windshield for the vent system. With the doors open, turn the vent system fan on high with the setting for fresh air. Take the Lysol and spray it into the inlet port at the base of the windshield. It may take a half a can of the Lysol spray to be effective.
If this doesn’t resolve the odor problem, then you may have to use a product such as this http://www.ac-evaporator-cleaner.com/frigi-fresh-single.htm
Tester
This can be done in your driveway for less than $20. Remove any obstructions in the evap tube with a wire ( this is the rubber hose that lets the a/c drain onto the ground. Pull the cabin air filter and with the a/c on and the blower on high spray an entire can of Lysol into the inlet. Replace the cabin air filter with a new one. Now, fresh as a daisy.
Be sure that you leave the AC controls in any position except OFF and RECIRCULATE/MAX when you park it.