Evaporator Drain

[xdgt03]

I believe my evaporator drain tube is restricted/clogged inside the evaporator box. I would like to clean this out.

I have read a bunch of threads and google searched this to death and have not found all the info.

Some threads say the drain tube runs below the evaporator on the passenger side out of the firewall. I do not see it. It is behind the insulation?

It seemed as though people were saying that it empties/drips on the passenger side but mine is dripping from somewhere above the transmission. Does the tube run from the passenger side firewall under the insulation to somewhere above the transmission? Or do they run inside under the console?

I read that on an E39 there is an evaporator access panel. Is there one on the E36?

Does anyone have pics of this? I have seen the realoem parts break down but the drain tube looks like it is one the driver's side and there is no other tube running above the trans.

Thanks for any help

[flyfishvt]

I don't know where the evap drain tube is but don't confuse that tube/drain with the one for your hood cowl. That drain tube runs down behind the heat shield and exits just above the tranny bell housing. This is the drain that gets clogged and causes water to backup into the DME compartment.

If you look at the cover for the DME the drain I'm talking about is about 3"-4" to the right of it as you are looking at it.

The cowl drain should only have water coming out if you just got the car wet. If you can see water coming out on a hot day with no rain then that is your evap drain. Follow the water to its source.

I'm glad you brought this subject up. Ive always wondered where that evap drain was.

[E36 manual]

i crawled under my car on a humid day and its a little oblong rubber thing on mine that drips onto the gearbox. the only way i can think of getting access to the evap coil would be throught the microfilter hatch mind you its a lot eaiser for us rhd folk to do

[xdgt03]

Yeah, I am not sure where the evap tube is. I did find a pretty good thread on the E39 with pics.

It was a hot day and no rain or water on the car. It was leaking water from somewhere above the trans. The water was clean/clear so not coolant or washer fluid.

The tube clogs inside the evap housing and it is a chronic problem until the evap goes bad and is changed. The housing gets dirty from dust, bits of leaves, and oil as the evap starts to go bad. It is not unique to BMW. When the evap is changed, it can be fully cleaned. When it gets clogged water accumulates and stinks, plus it causes the evap to become frosted over on particularly hot days when you need it most. Then the a/c system blows hot air.

Mine is moving some water which is good. Just not enough. If there is an access panel like the E39 then it is possible the clean it via that panel.

[E36 manual]

Yeah, I am not sure where the evap tube is. I did find a pretty good thread on the E39 with pics.

It was a hot day and no rain or water on the car. It was leaking water from somewhere above the trans. The water was clean/clear so not coolant or washer fluid.

The tube clogs inside the evap housing and it is a chronic problem until the evap goes bad and is changed. The housing gets dirty from dust, bits of leaves, and oil as the evap starts to go bad. It is not unique to BMW. When the evap is changed, it can be fully cleaned. When it gets clogged water accumulates and stinks, plus it causes the evap to become frosted over on particularly hot days when you need it most. Then the a/c system blows hot air.

Mine is moving some water which is good. Just not enough. If there is an access panel like the E39 then it is possible the clean it via that panel.

How do the leaves, dust etc. get to the evaporater if the air has to first pass through a microfilter?

[xdgt03]

Well I don't believe the filter is a perfect seal. When I changed mine recently it was clear that even with the foam seal around the filter, it is not a seal like that of the air filter.

Also, when changing the filter there was debris that came loose from the filter and was sitting in housing. I used a vac to suck it all out but the filter had been changed before and there is no telling if the person/place that changed it was as thoughtful.

It is not only leaves but small bugs, crumbs, dust, and dandelion/cottonwood tree puffs.

These can enter the system and fall into the housing through the vents too.

[flyfishvt]

Damn I hate cottonwood puffs. they clog eveything they touch ike a blanket and they are a bitch to remove. The place I used to work at had some cottonwook outside and it was a daily task to clean off the condensor coil of the A/C until the cottonwood snow stopped.

[Eric93se]

Does anyone know if we have access to the drain from the filter housing?

[xdgt03]

I'm not sure where the evaporater is. I presume it is on the others side of where the lines are that run into the firewall on the passenger side. This looks like it would be accessed by taking the glovebox out. There should be some sort of hose that runs off the bottom of the hvac casing that runs back out of the firewall and down over the trans somewhere. The clog would most likely be in the evaporater housing not in the hose above the trans.

[jerrycastillo]

Here is a picture of the A/C drain hose.

[ultimatetester]

I am sorry to revive this thread but did BMW really choose to just "leak" everything onto the gearbox right from the evaporator?
The above post shows how it looks from the underside, the following picture (which I stole) shows it from the interior:
IMG_6515.JPG

What I want to know is: if I want to retrofit this coming from manual controls without AC, I need to drill into my chassis for this rubber tube?

[mgoods50]

It has to have some kind of drain. Where you put it is somewhat up to you, but it has to drain.

It's just water. Cleaner than driving in the rain if you think about it.

[flyfishvt]

I am sorry to revive this thread but did BMW really choose to just "leak" everything onto the gearbox right from the evaporator?

Yes

[NickRay]

Sorry for the thread bump, anyone succeed at getting to the drain inside of the car, behind the evap?

[15flounder]

It is possible but it’s not fun. Seems like the cabin air filter in these cars was an afterthought given its location. As other posts mentioned, a lot of junk gets past the filter into the evap coil and drain pan. When I changed my filter, I duct taped a piece of vinyl tubing (maybe 3/4“ ID) to the shop vac hose and cleaned out all I could. Then I took a pump sprayer with a flexible wand and rinsed the coil and pan with hot water. Finished it off by spraying in a solution intended to prevent scum and deodorize household air handlers. All this worked for me and that was like 6 years ago. The trouble with this fix is I don’t think I ever saw the drain hole. I was just standing on my head in the floorboard, banging around in the dark. You might be able to see it but you’ll need light and at least one mirror.

[NickRay]

Yeah getting up in there really sucks. I blasted some pressurized air into the drain on the bottom end of it by the trans, hopefully that did the trick. Problem is, now I'm scared to start using my AC again because I dont want to have to go through the floor drying procedure again if it still leaks lol. I'll probably start using it tomorrow though.

[Eric93se]

Would be interesting to use a USB inspection camera and remove the air filter to see what's hiding in there. I have a cheap ~$20 ebay one, but I replaced the filter just a year ago and they usually get destroyed when removing them.

[gc325is]

Eric your USB cameras version you mentioned can attach to the Smart Phones so no need to drag a pc out
USB Endoscope

• 
  
  

https://www.amazon.com/dp/B07BF8N44X..._t3_B07BNB4T6S

[NickRay]

Update: pretty sure blowing the drain out with 100psi pressurized air fixed the problem. Now when I use the AC in this hot and humid GA summer, water pours out the drain by the trans and my floor is still dry. So to anyone with a wet passenger footwell, blast your drain tube with compressed air before you bother taking the dash out!

[runnr548]

I like the idea of blowing it out with air.