A/C foul odor

I have a 93 S-10 Blazer and sometimes it gives off a terrible odor from the A/C and heater vents. I've read that mold or mildew can grow on the evaporator core under the right conditions. I found a spray designed for this such problem and it appeared to work in the summer but it returned off and on for about 6 months. It is sprayed in each of the vents but I don't think is getting to the evap core. I tried spraying it and a Lysol type spray in through the fresh air intake through the cowl vent. But nothing seems to help. The GM "solution" is to remove the the evap core and scrub it with disinfectant. The problem is that it is a 5 hour flat rate time to remove and cleanup plus an A/C evac and recharge. Too costly. My question is does anyone have any other suggestions? Is there a specific spot that I can spray a disinfectant/mold killer that will be directed right to the evaporator? Is there something else I should use? I am thinking of locating the evap, carefully drilling a small hole in the housing around it, spraying directly on the evap, then sealing the hole. Help I am open to any suggestions? I need to do something asap, the odor is brutal.
Dwight

From under the hood, locate the A/C accumulator, there is an aluminum tube that runs into the evaporator housing near the top. A "straw" type spray nozzle on a spray can may fit in there, give it a shot! I wouldn't recommend drilling holes, the evaporator core could be damaged very easily. Hope this helps.

From under the hood, locate the A/C accumulator, there is an aluminum tube that runs into the evaporator housing near the top. A "straw" type spray nozzle on a spray can may fit in there, give it a shot! I wouldn't recommend drilling holes, the evaporator core could be damaged very easily. Hope this helps.

Thanks ,, I'll give it a shot :+). What do you suggest I spray in there? I read on another forum that someone tried Spray 9 and it worked great. I think something designed specifically for this problem would be better. The problem is that stuff is hard to find.

Thanks again for the location tip.

The odor is mold and mildew caused by condensation that doesn't completely drain out of the evaporator housing. Check the drain hose and make sure it's clear. Raise the right front corner of the vehicle, and you will see the drain hose attached to the evaporator housing. Any product that kills mold and mildew will work. Hopefully something with a more pleasant odor than you have now. If that doesn't take care of it, you'll need to go in there and wash the evaporator and housing.