A/C not "making water" - how to check for a plugged drain?

[jawn101]

Those of you who have been around a while may remember I've had no end of A/C questions over the years. Right now I'm quite satisfied with the performance of my system, but some recent threads keep bringing up one point I've never managed to tackle - "making water"

Ron, the resident A/C genius has frequently said it's easy to tell when your system is working right because it will make water (condensation on the coil as moisture is drawn out of the air). I have never ONCE seen a drop of water (coolant, oil, refrigerant, fuel... another story) under my car, even after running the A/C full blast in high temperatures.

Now, the A/C performs well enough for my tastes, though is nowhere near as powerful as my modern cars. That's a bit of a red flag to me, as I have heard from other owners that the A/C can freeze them right out. I'm a bigger guy (I like to call it drought and famine resistant) and tend to run warmer than most, and my wife says (complains, really) that the A/C in our D is plenty cold. So, maybe this is just me and that's fine.

But the lack of water under the car still has me wondering. I know Dave M has mentioned several times that his evap box drain was plugged and his coil was sitting in a puddle of its own drippings - and that an unclog job really helped improve his performance. To that end, I have tried a few times to run the A/C and remove the blower motor right after to see if there's water in there, and never really noticed anything. Was I too slow? My A/C drain hose is completely obscured by the fuel tank - I cannot see it anywhere at all under the car or I would have put some air pressure to it. I also briefly toyed with cutting the drain funnel that goes through the tub off to see if that helped, but for some reason I can't manage to get myself positioned with the tools to do it.

Anyone have any thoughts or suggestions on this? Are there other variables that could cause the A/C to be cold but not make water? Is it likely just a stopped drain? What should I do? I've considered removing the fuel tank closing plate to see if the hose becomes visible but I'm worried the tank will just fall on my head. Is that a thing that happens? That plate is virtually the only part of my car I've never removed.

[Michael]

The drain hose should be visible, it should run out around where the accumulator is. If it's been pulled off, there is still a small rubber grommet on the drain between the underbody and frame and that may be clogged, or being the hose is MIA, it may just be the water is being caught by the frame and closing plate. If you do find it, don't blow compressed air as it will just put the debris back up in the box. Use a long small flexible wire.

Keep in mind the AC system removes moisture from the air, if the air is fairly dry or the humidity is low, there may not be as much water. Also, if you run MAX position, the cabin air is being recirculated...which has already been cooled and dried by the AC system once, so that may play into the lack of run off.

[sdg3205]

Jon,

I too suffer from hypo-hydrosis.

I've never seen a drop. I've had my box apart for a heater core repair and it's spotless. I run ice cold r-12.

[jawn101]

The drain hose should be visible, it should run out around where the accumulator is. If it's been pulled off, there is still a small rubber grommet on the drain between the underbody and frame and that may be clogged, or being the hose is MIA, it may just be the water is being caught by the frame and closing plate. If you do find it, don't blow compressed air as it will just put the debris back up in the box. Use a long small flexible wire.

Michael - I should clarify, sorry! I can see that the hose *exists* but it completely vanishes into the frame and I can't see the open end of it. You're dead right about not blowing into the drain end of the hose - my intention was to put the air through from inside the box, but you're right - a wire or a snake of some kind would be smarter all around. Good call.


Jon,

I too suffer from hypo-hydrosis.

I've never seen a drop. I've had my box apart for a heater core repair and it's spotless. I run ice cold r-12.

What the crap! :)

I haven't removed or split my box but I have removed the motor and cleaned it out inside (all but the drain which I can't reach) and there's nothing consequential in there. One or two whirligigs but I wiped everything down and there was barely even any dust in there.

[Doogie]

I think the A/C Drain line can be viewed from above the car. You have to remove the Fuel Pump Cover to see it. Remove the Spare tire and then remove the cover from the bottom of the spare tire wheel well. (It's the rear portion of the Spare Tire Wheel well.) Once you have that removed, follow the two fuel pump fuel line towards the passenger side of the car. You should see an extra hose poking out at about the same place as the fuel lines are routed. (Where the Rubber Fuel line meets the hard line). There should be a hose "Not connected to anything". That's the A/C Condensate drain line. Run the A/C and see if anything drips out of it. (May take a while). Humidity will be the greatest factor also. Low Humid days might not produce enough water to see anything. High humidity days are when you see gads of water dripping from cars at stop lights.

My .02
worth .01

Doogie

[jawn101]

I think the A/C Drain line can be viewed from above the car. You have to remove the Fuel Pump Cover to see it. Remove the Spare tire and then remove the cover from the bottom of the spare tire wheel well. (It's the rear portion of the Spare Tire Wheel well.) Once you have that removed, follow the two fuel pump fuel line towards the passenger side of the car. You should see an extra hose poking out at about the same place as the fuel lines are routed. (Where the Rubber Fuel line meets the hard line). There should be a hose "Not connected to anything". That's the A/C Condensate drain line. Run the A/C and see if anything drips out of it. (May take a while). Humidity will be the greatest factor also. Low Humid days might not produce enough water to see anything. High humidity days are when you see gads of water dripping from cars at stop lights.

My .02
worth .01

Doogie

Thanks! Removing the fuel pump cover is how I know the drain line exists at least, I noticed it while I was installing my fuel pump combo kit. What made me think of this whole thing again is noticing the significant water under my wife's Honda after a drive today. I took a drive in the D under the same conditions and no water. RH today is 12% in town, which is pretty darn low. It's usually quite low around here, actually... maybe that's the whole problem. Low RH combined with a drain line that's routed funny so nothing drips out? If that's the case, why are our other cars dripping though? Weird.

[Michael]

Michael - I should clarify, sorry! I can see that the hose *exists* but it completely vanishes into the frame and I can't see the open end of it. You're dead right about not blowing into the drain end of the hose - my intention was to put the air through from inside the box, but you're right - a wire or a snake of some kind would be smarter all around. Good call.



What the crap! :)

I haven't removed or split my box but I have removed the motor and cleaned it out inside (all but the drain which I can't reach) and there's nothing consequential in there. One or two whirligigs but I wiped everything down and there was barely even any dust in there.

You can see it at the beginning by pulling the carpeting away from the passenger footwell. It is right up where the HVAC temp control cable is. You will see a small rubber grommet that connects the drain hose between the underbody and the frame, but if you pull it loose to clean it, you will have one Hell of a time getting it back on(ask me how I know).

[jawn101]

You can see it at the beginning by pulling the carpeting away from the passenger footwell. It is right up where the HVAC temp control cable is. You will see a small rubber grommet that connects the drain hose between the underbody and the frame, but if you pull it loose to clean it, you will have one Hell of a time getting it back on(ask me how I know).

Yep, that's the one I have been led to understand needs to be cut away to remove/replace. I just can't seem to get my hands in there to do it.

[DMCMW Dave]

Depending on how its routed, your drain may be dumping into the fuel tank cover, which will hold a bit of water, or the water may be running out the back of that near the center of the car. Also there is a huge amount of radiator fan wash in that space of the car, and in a dry climate the airflow from the fans may be evaporating the water as fast as it runs out.

To really test the drain, it's not all that hard. Take the fan blower out (inside the car). Remove the resistor pack so you don't damage it. Pour a cup or two of water into that area toward the evaporator. It should run out the bottom drain right away. Worst case you may need to pull the carpet back, carefully move the rubber "funnel" to one side and clean the crud out of the drain with a small wire. If it comes to this it's not a bad idea to move the carpet out of the way as you'll probably soak it.

I agree with the earlier comment - if you just blow compressed air into the drain, it will clear for a while but whatever you blew back into the case will just work its way down and plug it up again.

[jawn101]

Depending on how its routed, your drain may be dumping into the fuel tank cover, which will hold a bit of water, or the water may be running out the back of that near the center of the car. Also there is a huge amount of radiator fan wash in that space of the car, and in a dry climate the airflow from the fans may be evaporating the water as fast as it runs out.

To really test the drain, it's not all that hard. Take the fan blower out (inside the car). Remove the resistor pack so you don't damage it. Pour a cup or two of water into that area toward the evaporator. It should run out the bottom drain right away. Worst case you may need to pull the carpet back, carefully move the rubber "funnel" to one side and clean the crud out of the drain with a small wire. If it comes to this it's not a bad idea to move the carpet out of the way as you'll probably soak it.

I agree with the earlier comment - if you just blow compressed air into the drain, it will clear for a while but whatever you blew back into the case will just work its way down and plug it up again.

Wow... pouring water down the drain manually is so... obvious. Forest for the trees :mallet:

I will try that this week and see what happens. Thanks, Dave!! :)

[vwdmc16]

If it comes to it, We can pull the fuel tank together! it will be fun.

[jawn101]

If it comes to it, We can pull the fuel tank together! it will be fun.

LOL! But I just got it working... if I could remove the plate without the tank coming out I'd be good with that actually, the plate has some corrosion from a previous brake master leak that I need to address. But that's another issue :)

[DMCMW Dave]

LOL! But I just got it working... if I could remove the plate without the tank coming out I'd be good with that actually, the plate has some corrosion from a previous brake master leak that I need to address. But that's another issue :)

You can. Believe me, even with that plate off the tank is hard to get out.

[vwdmc16]

+1 Mine was very well wedged in with the factory foam.

[GS450-Junkie]

To really test the drain, it's not all that hard. Take the fan blower out (inside the car). Remove the resistor pack so you don't damage it. Pour a cup or two of water into that area toward the evaporator. It should run out the bottom drain right away. Worst case you may need to pull the carpet back, carefully move the rubber "funnel" to one side and clean the crud out of the drain with a small wire. If it comes to this it's not a bad idea to move the carpet out of the way as you'll probably soak it.

Anyone have pics of this?

[dvfr750f]

One issue to consider. How humid is it where you live? Dew point is impt. I lived in NM and the ac ran great with no issues. Moved to Norfolk Va where it is humid! and I discovered that my drain was clogged. As the evaporator shed water it accumulated and would spill out by the Bmotor when I cornered.
The drain itself is an L shape and gets smaller as it gets to the elbow. This means that probing the drain for crud wont work well. If you remove the drain from the accumulator...good luck getting it back together. So, if you are in a dry climate, you may not even have a problem. Just my experience.
Cheers