Why is my AC box condensing and dripping?

[YY1]

Both the car and the AC have run MUCH better since I evacuated and replaced the dryer.

No more getting hot in traffic/at stop lights and AC is blowing cooler.

However, and this started before I made the repair-

The bottom of the heater box is getting super cold, almost icy to the touch, and quite a bit of water is dripping off.

This is NOT coming from the gasket between the two halves (which is a terrible design, IMO anyway). You can see the nuts reflected in the condensation.

The gasket is not wet at all (I siliconed it and installed those nuts and bolts to increase the pressure vs the clips when I discovered the gasket was folded and causing a leak).

The drain to the engine compartment is working.

 

[YY1]

But dripping on the carpet can't be "normal".

 

[YY1]

I can't believe everyone else's does this.

 

[diesel_lv]

Not everyone's does it. My vent temps get down as low as 34°. Super cold modern system. But I live in the desert, super dry/no humidity, never a drop of condensation on the inside.

 

[YY1]

Oh, boy.

I does matter if mine is behaving abnormally.

...and if there is a fix that someone else may have experienced and cares to share.
(preferably that doesn't involve the complete disassembly of the heater box, and potentially evacuating my refrigerant again)

If I could believe this is "normal" behavior, as has been suggested, I guess I'd just be OK with warning any passengers that their feet are gonna get wet, and explaining to them that this is "normal".

 

[6872n73]

It would mean you are evaporator in the area around it is working very well. You could also try insulating that area of the box with a little bit of dynamat or equivalent.

 

[Mike67]

Your coil temp is below the dew point, no different than a cold mug of beer sweating.
Have to either raise the temp, lower the humidity or reinsulate to stop it.

 

[1 Wild R/T]

Your coil temp is below the dew point, no different than a cold mug of beer sweating.
Have to either raise the temp, lower the humidity or reinsulate to stop it.

There's your answer...

Florida humidity is certainly a factor... On a modern car the evaporator to evaporator case is pretty well insulated, most are supported on the edges which are covered by 3/8"-1/2" of foam... On old Mopars thats not the case...

 

[Virg464]

Just a couple of questions since I don't know the old AC systems very well. Did they use some type of expansion valve to control the Freon flow to the evap core? If they did it may be failing and allowing full flow all the time? Did they have drains installed in the HVAC plenum (box) for condensation to drain to the exterior? If so, it may be plugged and condensate is backing up into the box.

 

[1 Wild R/T]

Just a couple of questions since I don't know the old AC systems very well. Did they use some type of expansion valve to control the Freon flow to the evap core? If they did it may be failing and allowing full flow all the time? Did they have drains installed in the HVAC plenum (box) for condensation to drain to the exterior? If so, it may be plugged and condensate is backing up into the box.

Yes they use an expansion valve... Flow all the time is normal, It regulates/restricts flow to reduce evaporator pressure/temperature... To much flow would raise the pressure & therefore the temperature....

He shows a picture of the condensate drain & states that it is working...

 

[YY1]

Thanks everyone.

I may try the Dynamat idea.

I was concerned that insulation under the box would simply get wet and then possibly continue to drip..

I also wonder.....because it was blowing 48* before the fix, if that 3* is enough to push it over the edge.

For 8+ years it never did this, running on the previous charge in the same environment.

 

[Mike67]

Thanks everyone.

I may try the Dynamat idea.

I was concerned that insulation under the box would simply get wet and then possibly continue to drip..

I also wonder.....because it was blowing 48* before the fix, if that 3* is enough to push it over the edge.

For 8+ years it never did this, running on the previous charge in the same environment.

Make sure it is really dry before hand. Dynamat may work, if not you can get some of the foil back foam insulation from home depot that is a self sticking pretty cheap.

 

[MIKESPOLARA]

Thanks everyone.

I may try the Dynamat idea.

I was concerned that insulation under the box would simply get wet and then possibly continue to drip..

I also wonder.....because it was blowing 48* before the fix, if that 3* is enough to push it over the edge.

For 8+ years it never did this, running on the previous charge in the same environment.

What is the temp at the vents?

 

[YY1]

45*

 

[MIKESPOLARA]

Sounds like the lower end of the normal range for your high humidity area. Maybe just slightly over charged, lower charge just enough to raise outlet temp 1-2 degrees

 

[MoparLeo]

Vent temp is going to depend on the ambient temp/humidity, airflow thru the condenser...And the engines temperature. A hot engine with effect the condenser temp as the radiator is right up against the condenser which is trying to remove the heat from the refrigerant.
It is all a system that works together. If everything in the cooling system doesn't work properly then the a/c system will also be affected.
Whether you are sitting still, driving down the road at 45 mph, humidity and so... So many factors that you can't make blanket statements.
The op doesn't want to "work" and remove the a/c box and want a cure...
Who knows exactly what he will find inside, the box definitely is leaking so it is no longer sealed. Only proper way to do that is to open it up, clean it and use the proper sealers. Like trying to fix an oil pan leak without lowering the oil pan.
You can just goop up the outside but you haven't fixed the leak.
An evacuate and recharge are the last thing you do any time you open the system. .Have it done by someone with the proper equipment to make sure the proper charge of refrigerant and oil is in the system by measurement. The system is rated in oz. of refrigerant and oil. Walmart kits don't cut it.
Patches are temporary but repairs are for good.

 

[MIKESPOLARA]

Vent temp is going to depend on the ambient temp/humidity, airflow thru the condenser...And the engines temperature. A hot engine with effect the condenser temp as the radiator is right up against the condenser which is trying to remove the heat from the refrigerant.
It is all a system that works together. If everything in the cooling system doesn't work properly then the a/c system will also be affected.
Whether you are sitting still, driving down the road at 45 mph, humidity and so... So many factors that you can't make blanket statements.
The op doesn't want to "work" and remove the a/c box and want a cure...
Who knows exactly what he will find inside, the box definitely is leaking so it is no longer sealed. Only proper way to do that is to open it up, clean it and use the proper sealers. Like trying to fix an oil pan leak without lowering the oil pan.
You can just goop up the outside but you haven't fixed the leak.
An evacuate and recharge are the last thing you do any time you open the system. .Have it done by someone with the proper equipment to make sure the proper charge of refrigerant and oil is in the system by measurement. The system is rated in oz. of refrigerant and oil. Walmart kits don't cut it.
Patches are temporary but repairs are for good.

I understood him to say that it's condensing on the side of the box and not a drip from inside. If so, raising the vent temp slightly could eliminate that. Just the same as when you overcharge to the point of ice particles blowing out the vents when it's too cold (vent temp).

 

[YY1]

Yes.

Box is not leaking.

I've done done some diagnostic work on home AC systems in my time and generally when they "freeze up", they stop blowing cold inside the house. IIRC, that's not generally a case of being overcharged, either.

This unit continues to blow cold for as long as it runs.

I could try venting some 134. I suppose it can't hurt anything other than the comfort level inside the cabin.

 

[MIKESPOLARA]

You do it with the gauges hooked up and a temp probe in the vent and you decrease slightly to increase temp at vent, just a couple degrees warmer.

 

[MoparLeo]

Or you evacuate the system dry and recharge with the Measured/weighed amount of refrigerant that the a/c manufacturers recommend. This info is on the sticker in your engine compartment as well as your Factory Service Manual.
The picture just shows an extreme amount of moisture for simple condensation.