A/C Help !!
Thread Starter
Intermediate
Joined: May 2019
Posts: 43
Likes: 1
From: Virginia
A/C Help !!
I’m sure many of us have noticed with our cars, but upon starting my A/C in the car, a damp musky odor comes out and then goes away in a few seconds. Anyone with a similar problem. I need to get that smell out of my A/C.
Safety Car
Joined: Jul 2013
Posts: 4,408
Likes: 3,485
From: Granada Hills CA
Bulletin No.: 99-01-39-004C
Condition
Some customers may comment about musty odors emitted from the Heating, Ventilation and Air Conditioning (HVAC) system at vehicle start-up in hot, humid conditions.
Cause
This condition may be caused by condensate build-up on the evaporator core, which does not evaporate by itself in high humidity conditions. The odor may be the result of microbial growth on the evaporator core. When the blower motor fan is turned on, the microbial growth may release an unpleasant musty odor into the passenger compartment.
Correction
Many vehicles currently incorporate an afterblow function within the HVAC control module software. The afterblow feature, when enabled, employs the HVAC blower fan to dry the evaporator after vehicle shut down and this function will inhibit microbial growth. Technicians are to confirm that the customer concern is evaporator core odor and that the vehicle has the imbedded afterblow feature, as defined in the SI document for that specific vehicle model, model year and specific HVAC option.
personal note: THIS WORKS. Best $99 I ever spent at a dealer and I don't have to go through the routine of turning off a/c a few minutes before I arrive at my destination etc.
Thread Starter
Intermediate
Joined: May 2019
Posts: 43
Likes: 1
From: Virginia
Forget about the cabin air filter or spraying Lysol in the a/c vents. You need to have the "afterblow" feature enabled. GM issued a bulletin about this issue:
Bulletin No.: 99-01-39-004C
Condition
Some customers may comment about musty odors emitted from the Heating, Ventilation and Air Conditioning (HVAC) system at vehicle start-up in hot, humid conditions.
Cause
This condition may be caused by condensate build-up on the evaporator core, which does not evaporate by itself in high humidity conditions. The odor may be the result of microbial growth on the evaporator core. When the blower motor fan is turned on, the microbial growth may release an unpleasant musty odor into the passenger compartment.
Correction
Many vehicles currently incorporate an afterblow function within the HVAC control module software. The afterblow feature, when enabled, employs the HVAC blower fan to dry the evaporator after vehicle shut down and this function will inhibit microbial growth. Technicians are to confirm that the customer concern is evaporator core odor and that the vehicle has the imbedded afterblow feature, as defined in the SI document for that specific vehicle model, model year and specific HVAC option.
personal note: THIS WORKS. Best $99 I ever spent at a dealer and I don't have to go through the routine of turning off a/c a few minutes before I arrive at my destination etc.
Bulletin No.: 99-01-39-004C
Condition
Some customers may comment about musty odors emitted from the Heating, Ventilation and Air Conditioning (HVAC) system at vehicle start-up in hot, humid conditions.
Cause
This condition may be caused by condensate build-up on the evaporator core, which does not evaporate by itself in high humidity conditions. The odor may be the result of microbial growth on the evaporator core. When the blower motor fan is turned on, the microbial growth may release an unpleasant musty odor into the passenger compartment.
Correction
Many vehicles currently incorporate an afterblow function within the HVAC control module software. The afterblow feature, when enabled, employs the HVAC blower fan to dry the evaporator after vehicle shut down and this function will inhibit microbial growth. Technicians are to confirm that the customer concern is evaporator core odor and that the vehicle has the imbedded afterblow feature, as defined in the SI document for that specific vehicle model, model year and specific HVAC option.
personal note: THIS WORKS. Best $99 I ever spent at a dealer and I don't have to go through the routine of turning off a/c a few minutes before I arrive at my destination etc.
is there a part number for this? Anything after market that I can install myself?
and how long after the install of the afterglow does the odor go away?
Race Director
Joined: Dec 2013
Posts: 12,502
Likes: 3,629
Afterblow is a setting that is changed in the BCM via a tech II tool. If you don't have a tech II, or want to buy one ($109 for the VX GM Nano on amazon), then check around locally, since a lot of use own Tech II's and someone could swing by to turn on your afterblow feature on , instead of getting gouged by the dealer for a min of work with the tool.
Note, if you tell me what year your car is, I can give you a give of the menu's to use to get to the feature to turn it on with a tech II. Also, if you plan on wrenching on the car yourself, will need a tech II (clone), so spend the $109 now.
https://www.corvetteforum.com/forums...ternative.html
The low down, when you shut the car off, the A/C coil still has ice on it from using the A/C (humidity in the air that is pulled out of the air as it flows through the coil), so the BCM waits for a while for all the ice to melt/turn back to water once the car is shut off, then turns the fan on for a few mins to dry the coil out, and if your A/C box drain is not clogged, the water is drained out of the box as well.
So in your case, it's light mold on the coils that has grown, and could be that your A/C box drain line is clogged as well. So after blow will work to keep the mild from growing again, once you do get rid of the current mold problems.
So step one, pull the cabin filter, leave the filter door off, and with the car running, set the car to heater and make sure recirculation button is not light up , with the heater fan turned all the way up, and the windows open.
Now pick your scent, Since we are going to use the entire can through the cabin door open to saturate the coil to clean the mold from the coil and air box.
Step two, need to get under the car on the passenger side about the start of the tunnel well on the fire wall to pull the A/C box drain line to make sure it not clogged up.
Part #27.
Note, better to do this first in cause the drain pipe is clogged, but we need the drain line back on before you use the Lysol, since we want the air box to be pulling all the air from the cabin filter door. If you do pull the drain pipe and the A/C air box has water in it from a clogged pipe, give the box a few hours to dry out before you do the Lysol treatment to kill all the mold in the air box.
Once completed, leave the windows open for a while to let the car air out, and then install a new cabin filter and replace the door.
P.s. keep in mind that the air is drawn from the duct on the drivers side of the cowling, so not a bad ideal to use a water house to clean all the dirt/crap that may be in the duct up line of the cabin filter, before you change the filter. and again, let the water dry out before you start the lysol treatement.
As for Lysol treatments, if you are in an area that the humidity is say 40% or more as a constant, then do it yearly. In desert/dry climates, every few years will be enough, and may not need to turn after blow on in the first place, so long as you check the A/C box drain line yearly to make sure it has not clogged up. Hence bottom of hose has a small opening to keep critters from crawling up it.
Note, if you tell me what year your car is, I can give you a give of the menu's to use to get to the feature to turn it on with a tech II. Also, if you plan on wrenching on the car yourself, will need a tech II (clone), so spend the $109 now.
https://www.corvetteforum.com/forums...ternative.html
The low down, when you shut the car off, the A/C coil still has ice on it from using the A/C (humidity in the air that is pulled out of the air as it flows through the coil), so the BCM waits for a while for all the ice to melt/turn back to water once the car is shut off, then turns the fan on for a few mins to dry the coil out, and if your A/C box drain is not clogged, the water is drained out of the box as well.
So in your case, it's light mold on the coils that has grown, and could be that your A/C box drain line is clogged as well. So after blow will work to keep the mild from growing again, once you do get rid of the current mold problems.
So step one, pull the cabin filter, leave the filter door off, and with the car running, set the car to heater and make sure recirculation button is not light up , with the heater fan turned all the way up, and the windows open.
Now pick your scent, Since we are going to use the entire can through the cabin door open to saturate the coil to clean the mold from the coil and air box.
Step two, need to get under the car on the passenger side about the start of the tunnel well on the fire wall to pull the A/C box drain line to make sure it not clogged up.
Part #27.
Note, better to do this first in cause the drain pipe is clogged, but we need the drain line back on before you use the Lysol, since we want the air box to be pulling all the air from the cabin filter door. If you do pull the drain pipe and the A/C air box has water in it from a clogged pipe, give the box a few hours to dry out before you do the Lysol treatment to kill all the mold in the air box.
Once completed, leave the windows open for a while to let the car air out, and then install a new cabin filter and replace the door.
As for Lysol treatments, if you are in an area that the humidity is say 40% or more as a constant, then do it yearly. In desert/dry climates, every few years will be enough, and may not need to turn after blow on in the first place, so long as you check the A/C box drain line yearly to make sure it has not clogged up. Hence bottom of hose has a small opening to keep critters from crawling up it.
Last edited by Dano523; Jul 7, 2020 at 02:28 AM.
Thread Starter
Intermediate
Joined: May 2019
Posts: 43
Likes: 1
From: Virginia
Afterblow is a setting that is changed in the BCM via a tech II tool. If you don't have a tech II, or want to buy one ($109 for the VX GM Nano on amazon), then check around locally, since a lot of use own Tech II's and someone could swing by to turn on your afterblow feature on , instead of getting gouged by the dealer for a min of work with the tool.
Note, if you tell me what year your car is, I can give you a give of the menu's to use to get to the feature to turn it on with a tech II. Also, if you plan on wrenching on the car yourself, will need a tech II (clone), so spend the $109 now.
https://www.corvetteforum.com/forums...ternative.html
https://www.amazon.com/VXDIAG-Multip.../dp/B01NACTAY8
The low down, when you shut the car off, the A/C coil still has ice on it from using the A/C (humidity in the air that is pulled out of the air as it flows through the coil), so the BCM waits for a while for all the ice to melt/turn back to water once the car is shut off, then turns the fan on for a few mins to dry the coil out, and if your A/C box drain is not clogged, the water is drained out of the box as well.
So in your case, it's light mold on the coils that has grown, and could be that your A/C box drain line is clogged as well. So after blow will work to keep the mild from growing again, once you do get rid of the current mold problems.
So step one, pull the cabin filter, leave the filter door off, and with the car running, set the car to heater and make sure recirculation button is not light up , with the heater fan turned all the way up, and the windows open.
Now pick your scent, Since we are going to use the entire can through the cabin door open to saturate the coil to clean the mold from the coil and air box.
Step two, need to get under the car on the passenger side about the start of the tunnel well on the fire wall to pull the A/C box drain line to make sure it not clogged up.
Part #27.
Note, better to do this first in cause the drain pipe is clogged, but we need the drain line back on before you use the Lysol, since we want the air box to be pulling all the air from the cabin filter door. If you do pull the drain pipe and the A/C air box has water in it from a clogged pipe, give the box a few hours to dry out before you do the Lysol treatment to kill all the mold in the air box.
Once completed, leave the windows open for a while to let the car air out, and then install a new cabin filter and replace the door.
https://youtu.be/jDVOEPxdnOQ
P.s. keep in mind that the air is drawn from the duct on the drivers side of the cowling, so not a bad ideal to use a water house to clean all the dirt/crap that may be in the duct up line of the cabin filter, before you change the filter. and again, let the water dry out before you start the lysol treatement.
As for Lysol treatments, if you are in an area that the humidity is say 40% or more as a constant, then do it yearly. In desert/dry climates, every few years will be enough, and may not need to turn after blow on in the first place, so long as you check the A/C box drain line yearly to make sure it has not clogged up. Hence bottom of hose has a small opening to keep critters from crawling up it.
Note, if you tell me what year your car is, I can give you a give of the menu's to use to get to the feature to turn it on with a tech II. Also, if you plan on wrenching on the car yourself, will need a tech II (clone), so spend the $109 now.
https://www.corvetteforum.com/forums...ternative.html
https://www.amazon.com/VXDIAG-Multip.../dp/B01NACTAY8
The low down, when you shut the car off, the A/C coil still has ice on it from using the A/C (humidity in the air that is pulled out of the air as it flows through the coil), so the BCM waits for a while for all the ice to melt/turn back to water once the car is shut off, then turns the fan on for a few mins to dry the coil out, and if your A/C box drain is not clogged, the water is drained out of the box as well.
So in your case, it's light mold on the coils that has grown, and could be that your A/C box drain line is clogged as well. So after blow will work to keep the mild from growing again, once you do get rid of the current mold problems.
So step one, pull the cabin filter, leave the filter door off, and with the car running, set the car to heater and make sure recirculation button is not light up , with the heater fan turned all the way up, and the windows open.
Now pick your scent, Since we are going to use the entire can through the cabin door open to saturate the coil to clean the mold from the coil and air box.
Step two, need to get under the car on the passenger side about the start of the tunnel well on the fire wall to pull the A/C box drain line to make sure it not clogged up.
Part #27.
Note, better to do this first in cause the drain pipe is clogged, but we need the drain line back on before you use the Lysol, since we want the air box to be pulling all the air from the cabin filter door. If you do pull the drain pipe and the A/C air box has water in it from a clogged pipe, give the box a few hours to dry out before you do the Lysol treatment to kill all the mold in the air box.
Once completed, leave the windows open for a while to let the car air out, and then install a new cabin filter and replace the door.
https://youtu.be/jDVOEPxdnOQ
P.s. keep in mind that the air is drawn from the duct on the drivers side of the cowling, so not a bad ideal to use a water house to clean all the dirt/crap that may be in the duct up line of the cabin filter, before you change the filter. and again, let the water dry out before you start the lysol treatement.
As for Lysol treatments, if you are in an area that the humidity is say 40% or more as a constant, then do it yearly. In desert/dry climates, every few years will be enough, and may not need to turn after blow on in the first place, so long as you check the A/C box drain line yearly to make sure it has not clogged up. Hence bottom of hose has a small opening to keep critters from crawling up it.
appreciate all this info. I have a 2008 Z06. Luckily I now some people at chevy. I’m sure they can help with the programming
