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Clogged Evaporator Drain Tube?

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I've noticed some smell from the HVAC system. Also, some residue on the windshield. No wetness in the passenger footwell. Looking on the forum here, I concluded that there is a problem with drainage from the evaporator drain tube.

Short term, easy fix, which worked great at eliminating the smell was to "burn out" the bad stuff by running the heater on full blast for as long as I could take it.

But I'd like to fix the drain problem. I gathered notes from the forums (repeated below, with some questions) and yesterday checked the end of the drain tube with the AC running. No water came out, but there was a slight but steady flow of air coming out of it. The tube I think is the drain tube is black, about 3/8" ID, with some bends in it. I removed the kick panel by the passenger footwell, and could not see anything I could do there.

I have a compressor (that I use every chance I get, and then some) so if something needs to be blown out, I'm ready.

Any suggestions? I'd like to fix the drain issue, figuring the smell (which is gone for now after the "burn out") will take care of itself.


"It's the HVAC condensate drain pipe most likely; it gets full of nast and then the water backs up and won't drain properly; I've heard of this problem happening on other toyotas. Usually I just run the CC system with the AC off for the last 5 minutes of my drive and the problem hasn't recurred; but if you want to dig around on this forum you'll find instructions for finding the pipe (it's on the firewall on the passenger side I think) and how to clean it."

I found the pipe, but not how to unclog it.


"Take some Orange Blast, Simply Green or Lysol and spray into the vents directly under your wiper blades. Run the AC on high and re-apply the procedure a few more times. Every now an then you might need to do it again. It's caused by mildew."

I did this with Simple Green, since it seemed easy and harmless. To be clear, the vents I put it in were in the interior, right along the bottom of the windshield, making sure air was going in there, not out (like it does depending on the HVAC settings).


"96030 Kool-It Evaporator and Heater Foam Cleaner - The stuff foams. You put it into the ducting upstream from the evap core and run the fan, it foams and cleans the core, and exits through the condensate drain. The instructions are pretty comprehensive."

Not sure what "upstream" location I should use? Same as I did with the Simple Green?


"it's probably condensate from the evaporator thats draining onto the floor on the passenger side. Check the drain tube thats on the firewall under the passenger side and make sure it's not crimped, etc that would prevent the condensate from dripping out onto the ground. Run the a/c and look under the car on the passenger side and see if you have water dripping out the drain tube, if not, it's probably clogged up somehow."

"The drain tube connects to the evaporator housing and directs the collected water that condenses on the evaporator core through the firewall to drip on the ground . You can see the drain tube if you get under the car near the firewall on the passenger side and you should have water dripping out of the tube with the a/c running. If you're not seeing any water dripping on the ground, the drain tube is either disconnected or clogged up and in either case the condensed water will drip onto your passenger side carpeting instead of on the ground."

I had no water coming out of the tube and no water on the passenger side carpeting.

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