Mildew odor

Chevy Suburban a/c has gone “out” twice during 2006-07. Coincidentally there is a strong mildew odor which seems to occur each time the a/c stops working. Can these be related? We live in Houston with high humidity year-round. Also, effects of vacuuming and scrubbing the carpet vanishes within a day.

Maybe the AC drain is plugged?

We replaced the Climate Control Panel in the Suburban last summer. Then my husband felt it wasn’t cooling enough so he accidentally overcharged the system and it stopped working yet again. We do have a new compressor but our son is working in the installation so it hasn’t been tried. My husband said the carpet would be moist if the a/c drain was plugged so we don’t think it could be the cause of the persistent mildew odor.

There are a couple of possible problems.

If the drain clogs it will cause this.  It also can mean there is a unintended science experiment growing in the inlet path starting at the area under the grill in front of the windscreen and ending at the vents inside the cabin.  Dust and mold growing on the evaporator could also be a cause.  

Most auto parts stores carry a spray you can use, or you can pick up a can of Lysol from the grocery store, turn on the vent fan on high, do not set it to re-circulate and then spray in the vent outside where the air is coming in.

The question "does it have more of a problem or fresh air or re-circulate should really be answered first.

this sounds like the same thing that happens to people that have vinyl when it rains