A/C Evaporator Core Cleaning/Wallet Flush

[The Critic]

About every 12-18 months, I notice nasty odors from my car's vents, especially when the A/C is off.

I do replace my cabin air filter about every 15K but I admit to not being very diligent about turning off the a/c prior to reaching my destination.

Each time the odor issue happens, a clean up with an A/C evaporator foam product resolves the problem. I use the Toyota branded kit but I think Wurth sells an identical kit at a lower cost. Many kits only include a small amount of the foam chemical; you want a kit that includes 18oz of foam.

Prior to the service you need to remove the cabin air filter. Reinstall the filter door/tray. Locate the evaporator drain tube under the car. Inject 1/2 can. Allow the injected foam (which becomes liquid) to drain completely. Repeat the process for a 2nd time and empty the can completely. Wait again for the product to fully drain. Next, start the car and configure the HVAC settings to blower-max, outside air, a/c off and vent position to be face + footwell. With the doors and windows closed, empty the entire can of air refresher spray into the fresh air intake. Allow the car to run for an additional 5 min, then shut off and install a new cabin air filter. Reassemble as-needed.

This service makes the issue go away for at least 6 months, but usually a year. I call it a "wallet flush" because the correct fix is to manually disassemble and clean the evaporator, but the labor involved rarely makes sense.

 

[Railrust]

Pretty cool, I'll have to try this.

 

[JZiggy]

This summer I cleaned my evap core for the first time on my 99 4Runner. It does not have an AC filter. I removed the fan and sprayed coil cleaner in there and let it drain out. I added a drain tube extension to be able to catch the fluid. After emptying two cans I sprayed it down well with a mild isopropyl alcohol & water solution. After a few months of use now I can say it was an improvement and no smell has shown up.

 

[t1snwrbrdr12]

Used to perform various services like this at the dealer. Our product and method changed from year to year depending on our vendor. For awhile we had some fogged that went on the floor, put the air on circulate and it'd draw the fogged chemical through the hvac box. We kept falling back to these foams that injected through the drain tube and finished with a spray through the fresh air intake just like you used.

Not sure you've ever experienced this, and nobody I've come across has either in my years in the dealer...but my 03 accord ended up needing a new hvac box after one of these foaming cleaners. The blend door became stuck to the hvac housing. I removed the blend door motor, found the door physically stuck. The foam insulation that creates the seal between the door and housing melted. Not sure I can blame this on the foaming cleaner or not, but it was very unfortunate. I hate pulling dashes personally.

 

[nthach]

I've used something similar from MOC a while ago that I drilled a hole in my evap case for it to work. When I removed the evaporator case to replace a evap valve, I used this to clean the evaporator core while I flushed the old oil out of it:

http://www.rbnainfo.com/product.php?productLineId=463

On my parent's van, I used a "fumigator" from a shop in Japantown, SF to help nail down a funk. It worked... kinda. Turned out to be fast food garbage under a seat. Meguiar's sells a similar thing.

 

[AC1DD]

Tip depending on which car you own, some can access their evaporator from the blower fan motor mounting area, unscrew the blower motor and remove you can see into the evap, you can also use mild dishwashing soap mixed with water and use a hose to gently flush the mixture out of the drain tube. I think this does a more effective job.

In any case folks almost ALWAYS overlook a dirty evap as being a cause of serious cooling problems with the AC, if the fins are plugged you'll have low air flow with recirulation turned on and poor cooling since you'll get evap freeze up from lack of air flow.

 

[berniedd]

Just 2 hours ago, I was watching a Wheeler Dealers episode where a professional detailer used a steam making machine to clean the ducts and evaporator of dirt and odors. They stuck the steam hose onto an air side vent and the steam exited the other side and center dash vents. I suppose the evaporator could be better cleaned if one were to shut all exit vents and let the steam make its way deeper.