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Getting moisture out of AC system

26K views 22 replies 9 participants last post by  ross1  
#1 ·
Hey folks.
Well, the windshield on my 1993 Camry has a tendency to fog up sometimes, and all the time in the rain. With the AC on, it should be removing moisture from the car and preventing fogging, so this tells me there's moisture in the system (and the vents on top of the dash for de-fogging and leaking, but I know that already). Is there a way to remove moisture from the system, thus preventing fogging?
Thanks.
 
#2 · (Edited)
The only way there could be moisture in the system is if the drain tube is clogged and water is accumulating in the evaporator assembly. You can easily check this by running the A/C and seeing if a puddle of water accumulates under the car.

edit - assuming you don't have an actual leak somewhere that lets water into the car.
 
#7 ·
you're right. i assumed his a/c is not working right. it doesn't mean it's low on gas. i t might have simply "dirty" gas. i see fogging with a/c on only when there is a problem with a/c system already.

checking for clean drain hose is a good idea though, might be clogged.
 
#5 ·
An additional technique you ought to consider is keeping the inside of your window clean. By keeping it clean you reduce the number of nucleating particles for moisture to condense onto. You'd be amazed at how much less fogging you'll see on your window, and also how quickly it will clear up, when it's cleaned very well. Food for thought.
 
#6 ·
An additional technique you ought to consider is keeping the inside of your window clean.
Excellent point. I once applied Rain-X to the inside of my windows. It was difficult because of the rake of the windshield (Rain-X is a bitch to apply, you have to polish like crazy to get the haze off) but for a long time, the windows hardly fogged up at all it was awesome.
 
#9 ·
Speaking of outgassing, whatever the previous owner put in my dash, the stuff evaps and forms a nice thick layer of oil on my glass. :disappoin I have a home brew cleaner with vinegar in it, works very well.
 
#12 ·
Probably ArmorAll.
Likely. I cleaned most of it off, I learned long ago that AmorAll loves to evap and cause a greasy mess. Don't know about the cracking, I don't use it anyway, but now that you mention it I know a few people that use it that have cracked dashes :lol: What's a good treatment? I've tried several, all have been okay not great.
 
#11 ·
You have to operate AC to help dehumidify your cabin, especially with Florida humidity. And as suggested, you have to make sure the drain tube on the bottom side of the car is not plugged, this is how condensation from the evaporator drains out of the car. A plugged drain tube will make things much worse.

So no, you don't have moisture in your AC system. You have moisture in your ventilation system.

Also, you have to make sure it's not a coolant leak in the heater core that's causing the fogged windshield. You're not losing coolant are you? Or smell coolant in the cabin?
 
#13 ·
If you have moisture in the AC lines, you are in SERIOUS trouble. That would mean A. you have a leak. or B. it entered when the AC was recharged. The moisture mixes with the refrigerant inside and creates a bad acid and wrecks havoc on the whole system.

The problem you are having doesnt sound like moisture in the AC lines, but more like something not in the actual air conditioning system (components inside the engine bay are fine).
 
#14 ·
Wow, lot's of replies this time! Thanks folks.
To address the responses:
It doesn't appear from a distance to be clogged. I do have drippage after a few moments of running the car. Last year, I was pulled out of class because one of the school monitors saw a puddle of liquid coming out of my car. It was quite a lot of liquid, and we deduced it was simply from the AC. The liquid didn't appear to have a smell, but had that oily coloration in the right light- could have just been the pavement I was parked on being dirty.

As far as the smell of coolant in the cabin, I'm not sure what coolant smells like, so I'm not sure.

Does the Camry have a 'receiver dryer'?

Something else to note is that during the day with the AC on, the windshield can become completely fogged from the inside because of the vent leak. When there's enough fog, there appears to be a green haze or green spots on the windshield. Haven't seen this happen for a while.
 
#15 ·
As far as the smell of coolant in the cabin, I'm not sure what coolant smells like, so I'm not sure.
It smells sweet, very distinct.
Does the Camry have a 'receiver dryer'?
Yes, I think every auto A/C system does.
Something else to note is that during the day with the AC on, the windshield can become completely fogged from the inside because of the vent leak. When there's enough fog, there appears to be a green haze or green spots on the windshield. Haven't seen this happen for a while.
What kind of vent leak? A green haze sounds like coolant to me. Is your coolant green? Do you you lose coolant and have to add?
 
#16 ·
The vent on the top of the dash used to defog the windshield.
As far as a sweet smell, no, and I don't have to add coolant to the system.
As far as the color, I'm not sure. Where can I check?
Also, I checked the meter thing for the AC in the front of the car, it's white with no bubbling last I checked.
 
#17 ·
Back up a little (literally), fogging can come from any moisture sources including puddles in the trunk, wet carpet, spilled milk, plugged door drains (less likely).

If the heater core doesn't smell sweet with the heat on high, its prolly OK. So check the rest of the car for dampness. Pull out those plastic holders in the trunk and make sure water is not trying to float the spare tire.

As said, a clean car will fog less often!
 
#18 ·
You should really get the vent fixed, without air blowing directly onto the windshield the defogging will be greatly reduced.

If you don't smell coolant or the level doesn't drop, you don't have that problem. But how do you check the level and not know the colour? :eek::D Just look at the overflow tank (by your windshield washer reservoir).
 
#19 ·
It's a dark color as I recall, never opened it up, just looked on the side to make sure the level is right. The tank is yellow and nasty and a corner of it is corroded almost all the way though. So is my windshield wiper tank, but it's completely corroded through. I'll take pictures so you can laugh at my misfortune. XP
 
#22 ·
If the AC is set to full blast, doesn't the system set it's self to recirculate? (mine's an 01, it does) If it's recirculating the cabin air, I'd think it wouldn't fog up. Now once you introduce the humid air from outside, then an undercharged system could be overwhelmed with humidity. Just a thought. I spent the last five years keeping up with the AC system in a british car. I recently called it quits and bought my camry so I could open the hood less often than the fuel door. The basic principle of all AC systems are the same, so I figured my input may help.
 
#23 ·
Moisture IN the A/C system won't cause windshield fogging.
You may have condensation on the outside, do the wipers remove it? This is normal in humid conditions.
A leaking heater core will introduce water vapor into the defroster air causing fog or mist on the inside of the glass.
Lastly, if your system isn't cooing properly it also isn't dehumidifying.