I've been searching for 30 mins tonight, but no luck. I'll try the HVAC section after this---

The AC recycler button(center, right above the climate ****) is randomly turning off. It started a few days ago and seems to be happening about once a day. I notice it when the AC suddenly drops in pressure, but can push the button and it goes back to max power. Anybody have any ideas on this?

Thanks--

 

It's been doing it as long as you have owned the truck. You probably did not notice it. For some stupid reason, that is how it was designed. I hear if you use the "Auto" function, it will not turn off. I have not tried that one out yet.

 

Recirc is designed to turn off after a fixed period of time. This is to keep the interior from getting too humid, and streaming up the windows in certain conditions.

 

Ok, well I guess I feel better--thanks for the replies.

 

Um, actually it shuts off to get fresh air (oxygen) into the cab.
Recycle doesn't allow fresh air to get in, thus the air in the cab fills up with CO2 pretty quickly, which makes you go to sleep, or get a headache.

It is not life threatening in a non-sealed cab.

The moisture in the air is removed when the air flows over the cold evaporator, thus drying the air. This is why the compressor turns on when you use defrost, to dry the cabin air faster. By removing the moisture the windows defog much faster than they would solely from the air blowing across them.

Leaving a tight vehicle on recycle is actually sort of dangerous, so even with the manual A/C they set it to release if you change the settings or shut off the key.
It's a safety/comfort thing.
Chris

 

WOW.....I've never thought about that....I leave mine on all the time....actually on my other vehicles....I guess this could be a good lesson!

 

Well, if your other vehicles are not tight, or if you have a window cracked it does the same thing as turning off recycle.

One of the funny posts you see is someone who has their window down or even cracked a couple inches complaining about poor A/C.

On the Regular cab trucks the air gets stuffy in about 20 minutes of recycle with two adults.

Not life threating but uncomfortable.

Very few vehicles are so tight that it is a true danger. You would have to drive for three or four hours without letting any new air in the cab to be truly dangerous, and again, that is only if the truck was VERY tight. Most ain't...

And if you did find it hard to breath, most people would roll down a window, thus curing the problem for the next three hours.
Still, over using recycle is not to your advantage, so it makes sense that on more modern cars the recycle is set to disengage pretty quickly.

Chris

 

I'm sorry I have to disagree.The system is not a closed system.There are vents in the cab that allow air to vent to the outside.Thats why cars today dont have to worry about the windows exploding when all are rolled up in the hot summer.

 

I've never noticed mine turning off.

How long do you have to run it on recycle before it kicks out?

Mine stays on recycle because it stays on max ac. The ac on these trucks is nowhere near what they have been on any other Ford truck that I have owned.

 

The vents (on the regular cab they are behind the plastic rear of the cab) are 'flapper valves'. That is, at rest they are closed. Otherwise dust, bugs, mice, fumes etc. would come into the cab. When the system is taking air in from the front through the vent under power or through the A/C when NOT on recycle, the vents at the back allow the air to escape.

These one way vents do nothing to allow fresh air in when you are on recycle, or at any other time. They only let air out.
They are not complicated devices.
No more sophisticated than a dryer vent flap.
They let air cycle through the cab, and they 'flap' open when you slam the door. They sometimes stick; often they can be blocked by laying down a coat or soft bags near them.

The system functions as a 'closed system' when it is on recycle. That does not mean it is hermetically sealed, just that there is very poor ventilation when the system is closed. That is how it is designed because that is the most efficient way.

Think of it this way; a paper bag is not air tight. You could put one over your head and tape it closed around your neck and you would never smother. You might get groggy in about ten minutes, but you would never smother.
You wouldn't be too happy though.

There is a reason they let fresh air into the truck.

Think how much easier it would be to design a truck with no vented air, always on recycle. The heater and A/C would work twice as well and thus could be built much smaller, cheaper and more fuel efficient. Wonder why they don't do that....
They must be pretty stupid...

Kidding of course. Ask any safety engineer that works with breathing air about this stuff if you want to get more information.
Chris

 

Im glade this thread came up Ive notice the same systems when I go to AC recycler .I was going too take in for service .BUT mine doesnt take long to cut off though .Hear in Fla.I have a 04 screw

 

While in Recirc mode, moisture is re-introduced to the interior by the individuals in the vehicle (provided they haven't died from lack of O2...LOL).

In some conditions, there is more moisture inside than in the fresh air from outside.

 

I think dead people would give off some moisture too...

Seriously, the exhaled water vapor is cleared by the evaporator, just the same as intake air. Not perfectly but it still drops it to 20% or lower humidity pretty fast.

It can be true that sometimes the air is dryer outside, though that is rare even here in the Mojave Desert.

Because it is so dry here, lots of people using refrigeration A/C have to use humidifiers in their houses so their sinuses don’t dry out. Unlike swamp coolers (which raise the moisture content of the air) refrigeration coolers suck the water right out.

Chris