I have a 2001 4.6. I am not enjoying the smell of coolant in my truck. There is a mist that comes through my vents when I have the air on. It doesn't do it when the defrost is on. The other day I noticed that there was an extreme amount of fluid leaking from the passenger side, by the door, from over the frame. This smells like water. I am not losing coolant, truck isn't overheating. I don't feel any moisture on the floor, so not sure if it is the heater core. (I live in FL, so I haven't tried it with the heat on). Does anybody have any idea what this is? Had one person tell me to flush the cooling system, that it worked for them. There is 110,000 miles on the truck, and I haven't flushed it since I have owned it. (About 50,000 miles). Please help!

 

Welcome!

Does it do this all of the time, or a intervals?

Sometimes, your system can be low of freon. When this happens, the ac coil can freeze over, and when the compressor cuts of from the low pressure switch, the coil warms up and melts the moisture, and blows fog out of the vents.
Another thing to check is you coil drainage tube. It is on the passenger side on the firewall under the hood. Sometimes slime, or an insect can plug then up, and blow moisture out inside.

You did say" It does not smell like coolant" right? You usually don't smell coolant unless the temp ****( that controls water flow through the heater core ) is turned up some. Or the climate control opens it to maintain temperature, depending on the type of system you have

 

It blows the mist whenever I turn the A/C on. I can smell coolant whenever I turn my truck on. The fluid leak I discovered was what didn't smell like coolant. If I turn the air on as soon as I start the truck, it is blowing an odorless mist into the cab.

Even if I use the panel/floor control, it blows the mist. It does blow ice cold on the panel/floor setting. The A/C and MAX A/C settings blow ice cold air. Is this a separate problem from the leak I have? Or, could slime or a bug CAUSE that leak, and that smell?

 

Even on AC, with the temp **** turned down, the oder is like coolant? Or it just stinks?

 

The mist doesn't have an odor. The smell of coolant is strong whenever the truck is turned on. But, the mist coming from the vents and the coolant smell began at the same time, so I figured the problems were related. I can see where if I have a blocked hose or tube where it could cause both. I ran the engine, and looked in the engine compartment. I do not see a leak. I discovered the leak coming from the passenger side by the frame (location of a condensor maybe) when I dropped something after cleaning my truck from work. That moisture leaking there is odorless and not thick. But, even when I go to my truck at the end of the day I can smell coolant. I go about 8 hours between use of my truck at work.

 

The leak on the right side is the condsate line leaking, as it should. That water should be cold.
The coolent smell, is it storngest in the cab, or under the hood?

 

It is strongest in the cab. You can hardly smell it when you stand in front of the engine. However, I have not felt any moisture in the cab like a leaky heater core. And like I said, I am not overheating or losing coolant.

 

It sounds like there is a leak before the temperature control valve on the heater core. Is it a manual unit or and electronic temp control(EATC)?

The water you mentioned running down the frame. Is it ever steaming?

 

It's a manual unit. The water down the frame isn't steaming. If there is a leak before the temp. control valve, is that where I have to take the dash off? Wouldn't I feel the leak on the carpet in the cab? Can I test it by running the heat?

 

Have you checked where the heater hoses go through the firewall?
It's sounds like you do have a heater core leak, but as you've already noticed, some of the signs aren't there. Maybe someone else will chime in , that has had a problem like this one themselves.
Good luck!

 

I haven't checked where the hoses go through the firewall. I thank you for the help. I'll get started trying to locate the leak. If I have to take off the dash, that will be next week. Was hoping to avoid that. Will let you know how it goes though. Thanks again Tumba.

 

Tumba, now I am a liar. I checked my reservoir on Tuesday, and had coolant. Just checked it, and EMPTY! Which is great, considering I just towed my boat an hour away yesterday. Now, I would have to say leak in heater core?

 

One more thing. Would the heater core leak with the air off?