Corvette ED

The last two times i drove my 07 the A/C had a smell at start up and then it went away. It was 98o today and I noticed hardly any water coming out of the evaporator. It may be blocked and thats why the smell started. I know the C5's had problems with the hose getting pinched shut.

Where is the hose on a C6?

torquetube

Passenger side, right above the exhaust. It's hard to reach but not impossible. Wait until the engine has cooled down - everything around it will be hot for hours after running.

I roto-rooted my car's A/C drain out the other day using a welding rod with the end bent into a loop (to avoid puncturing anything).

Corvette ED

Sound like the same place the C5 was. Was yours blocked?

ChevyDave

not a camera pic but parts blow-up, item #27..

which hooks at part #24..

glenB

The odor is a common problem. if you do a search here you will find many threads with the same concern. See the TSB below

You might want to look into the 'after blow' feature and this TSB #99-01-39-004D

Bulletin No.: 99-01-39-004BDate: May 29, 2007
TECHNICAL
Subject:
Air Conditioning Odor (Install Evaporator Core Dryer Kit and Apply Cooling Coil Coating)
Models: 1993-2008 GM Passenger Cars and Trucks (Including Saturn)
2008 and Prior HUMMER H2, H3

All Equipped with Air Conditioning
Supercede:This bulletin is being revised to update the vehicle applications, model years, correction procedure, parts information and tool numbers. Please discard Corporate Bulletin Number 99-01-39-004A (Section 01 - HVAC).

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.

There are several other possible sources of a musty odor in a vehicle. A common source is a water leak into the interior of the vehicle or foreign material in the HVAC air distribution system. Follow the procedures in SI for identifying and correcting water leaks and air inlet inspection.

The procedure contained in this bulletin is only applicable if the odor source has been determined to be microbial growth on the evaporator core inside the HVAC module.

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.

Refer to SI for enabling the afterblow function. Vehicles being delivered in areas prone to high humidity conditions may benefit from having the afterblow enabled calibration installed prior to any customer comment.
If the vehicle is not factory equipped with the imbedded afterblow enable feature, it may be added with the Electronic Evaporator Dryer Module Kit (P/N 12497910 or AC Delco 15-5876).

When installing the Electronic Evaporator Dryer Module, you MUST use the included electrical splice connectors to ensure a proper splice. Complete detailed installation instructions and self testing procedures are supplied with the kit. If necessary, the Electronic Evaporator Dryer Module may be installed underhood if it is protected from extreme heat and water splash areas.

To immediately remove the evaporator core odor on all suspect vehicles, it is necessary to eliminate the microbial growth and prevent its re-occurrence. To accomplish this, perform the following procedure:
Vehicle and Applicator Tool Preparation The evaporator core must be dry . This may be accomplished by disabling the compressor and running the blower fan on the recirc heat setting for an extended period of time.

Note: Compressor engagement will cause the evaporator core to remain wet and will prevent full adherence of the Coiling Coil Coating to the evaporator core surfaces.

Verify that the air conditioning drain hose is not clogged and place a drain pan beneath the vehicle. Place a protective cover over the carpet below the evaporator core. Remove the cabin air filter, if equipped, and cover the opening prior to applying the Cooling Coil Coating, as the product may clog the filter. If the cabin air filter appears to have little or no remaining life, suggest a replacement to your customer.

If the HVAC module has a blower motor cooling tube, be careful NOT TO SPRAY THE COOLING COIL COATING INTO THE BLOWER MOTOR COOLING TUBE.Attach the Flexible Applicator Pressure Spray Tool (J-43810-20A) to a compressed air line operating at 586 kPa (85 psi) to 793 kPa (115 psi).
Shake the bottle of Cooling Coil Coating well. Screw the bottle onto the cap on the applicator tools pick-up tube.

NOTE: The pick-up tube is designed for 120 ml (4 oz) and 240 ml (8 oz) bottles and should coil slightly in the bottom of a 120 ml (4 oz) bottle

Use one of the following three methods to apply the Cooling Coil Coating.If the Pressure Applicator Spray Tool (J-43810-20A) is not available, the Cooling Coil Coating is also available in an aerosol can (P/N 12377951 (in Canada, 10953503)).
Application Through Blower Motor Control Module OpeningRemove the blower motor control module (blower motor resistor). Refer to the
applicable procedure in SI.
Clean any debris or foreign material from inside the HVAC module and on the evaporator core surface. Apply the Cooling Coil Coating directly to the evaporator core through the blower motor blower motor control module (blower motor resistor) opening. Use the flexible wand to direct the Cooling Coil Coating over the entire evaporator core and surrounding gasket surfaces. When the application is complete, install the blower motor blower motor control module (blower motor control module).
Application Through Blower Motor Opening Remove the blower motor. Refer to the applicable blower motor removal procedure in SI.
Clean any debris or foreign material from inside the HVAC module and on the evaporator core surface.

Apply the Cooling Coil Coating directly to the evaporator core through the blower motor opening. Use the flexible wand to direct the Cooling Coil Coating over the entire evaporator core and surrounding gasket surfaces.
When the application is complete, install the blower motor.
Application Through a Hole in the HVAC Module If neither of the two previous application methods are available, it may be necessary to drill a hole in the HVAC module. Locate an area of the HVAC module between the blower motor and the evaporator core. Drill a 10 mm (3/8 in) hole in the HVAC module. Use caution to keep the drill clear of the evaporator core and the blower motor fan. With the air distribution vents closed and the blower motor fan speed on HIGH, insert the applicator tool into the hole and spray the Cooling Coil Coating into the airstream toward the evaporator core. Use a GM approved RTV sealant to plug the hole in the HVAC module. After the Cooling Coil Coating application is complete, start and run the vehicle for approximately 10 minutes, with the compressor disabled, HVAC mode set to Recirculate/Max, heat set to full warm, blower motor fan speed on high, and one window open approximately 12 mm (1/2 in). This cures the Cooling Coil Coating onto the evaporator core surface.

While the engine is running, rinse the applicator tool with warm water to prolong thelife of the tool. Be sure to spray warm water through the nozzle to rinse out any residual Cooling Coil Coating still in the capillary pick up tube, otherwise it will dry and clog the applicator tool. Also remove the small green valve from the bottle cap and rinse it thoroughly while rolling it between two fingers and then reinstall it. If this valve is clogged the Cooling Coil Coating will not flow through the applicator tool.
Shut off the engine and enable the compressor again.

Verify proper HVAC system operation.

Remove the protective cover from inside the vehicle.

Remove the drain pan from underneath the vehicle.

Reinstall the cabin air filter if necessary.

torquetube

The A/C was draining slowly (as indicated by the odor, and a very long pause between the characteristic drip-sizzle sound). It was back to normal after I rooted it out.

chevyc6z51

If the ac smells after you turn of the ac for a few mins. Will the dealer cover this under bulletin? And will this fix that?

glenB

Only if it's under the 3/36

A TSB is just a notice to say 'hey! look here!' it is not a recall. And yes, if the coils are cleaned properly it will correct the issue.

VET4LES

I had the after blow turned on and turn off the a/c a few miles from home and the smell stopped.

Corvette ED

I am thinking this is whats wrong with mine. It has been in the upper 90's for the past week and the smell just started. There was hardly any water dripping out so I think it is blocked. I have had this with a few C5's where the end was either blocked or sucked shut. I will have to take it to work and put it up on the lift and see what is going on.

torquetube

I did the job from above. I'm not even sure you could reach the drain from under the car.

AORoads

I don't have the "afterblow" but turning a/c off and fresh air fan position a few minutes before shutting engine down used to be the method to use. I do it on most cars I drive. Considering the heat in the last couple weeks, it's not easy to do, but it still seems to work for me.

Corvette ED

I just got done with it. I was able to get to it from under the car. I started the car and push the AC on and let it run for 10 mins. Nothing came out so I stuck a wire up in the hose and rooted around and then it started dripping. I think where the hose is and the exhaust is so close the end of the hose from the heat must melt shut. I will have to see how it is over the weekend.

torquetube

In my case, I didn't notice an obvious obstruction at the outlet of the A/C drain. Whatever was clogging it was further up inside the hose.

This system could use a cleanout of some sort.