A/C smells like mildew

Can anybody give me any tips on why lately my A/C has been smelling like mildew right after I start the truck? We have just gotten some bad rain for a week and a half. I don't know if that has anything to do with it or not, but I started smelling it in the middle of the weather. I guess I am going to bring it to the dealership, but I am not sure they will be able to do anything about it anyway. If anybody has any ideas please help. Thanks!

Well if its 99-02 you can replace the in cabin microfilter. That may help, but most likely the smell is coming from the bacteria living in the fins of the evap core. You can curb this by turning the AC off and letting the fan run for a minuite before shutting the truck off. You can also buy the aerosol cleaner and deodorant for the evap core.

I have heard this filter mentioned before... does the 2003+ have this filter as well? If so can I assume it is located under the dash on the passenger side of the cab?

No the 2003+ does not have it.

Does the 2000 C35000 Silverado have the filter?

I dropped the lower part of the heater box on the passager side and when I looked inside all I saw was the heater core.

Is it deeper inside the box?

Thanks.

I brought my truck to the dealership 3 times for this problem now. Every time they tell me they have cleaned and flushed the A/C system, but every time I get it back, after a day or two it starts to stink again. It is only getting worse. When they give it back to me, it smells like they just sprayed some air freshener in there and that's it. Where can I get some of that deoderizer and cleaner and can I do anything else to try to get rid of this f'ing stench?!!!!

Oh yeah, it's a 2003 1500 LS 5.3L

Stupid ques but does water drip out of evap coil onto ground? Sometimes hose gets stopped up and water sits instead of draining.

This has happened to my 93 several times before. and the mildew smell is actually mildew in your a/c system. to prevent it you can turn off the a/c and run the fan before you turn off the truck to dry up the a/c system and prevent the growth of mildew. now as far as getting rid of the mildew already there, buy a can of lysol antibacterial spray and spray it in the intake for the a/c (under the passenger side dash) while running the a/c. continue that until the smell goes away.