This is my first vehicle with automatic climate control - have a question (or 2).

Since I've had the truck for about 3 weeks now, I've left the system on 'auto' and am quite surprised at how well it works.
Also since I've had it, the A/C button has been on (lit) - I thought that maybe the system was automatically turning the A/C on and that was why it was lit.

On the way home today, it was raining, and 55 deg.F - as usual the 'auto' was working fine, but still noticed the A/C button lit. So I hit the button, and the A/C light went out. Soon afterward, the windshield started fogging up. Turning the A/C back on cleared the windows up right away.

So now I am confused a bit - shouldn't the 'auto' function turn the A/C on and off as is needed by itself?

 

It should. It worked perfectly on my 2004, and has worked perfectly on my 2009 so far. I'd say the A/C button is lit probably 97% of the time, both trucks. Very rarely do I see it unlit, and that's both trucks combined since 2004. The system must use the A/C to keep windows clear, help with humidty buildup, etc.

 

Now I am wondering that I possibly turned the A/C off manually by hitting the button when it was lit......

 

From what I know the auto feature just controls the airflow in the cab to regulate the temperature you have it set. When you hit the A/C and the lit went off you turned the compressor/condensor circulation off. If you know the basics of HVAC systems you know that to cool air it must be compressed and in order to do so the water needs to be condensed out of it. And to heat air you must add the moisture back. By cutting off the A/C you increased the humidity and fogged.

 

Yep, that's all you did. Will most likely come back on again by itself next time you start your truck with EATC engaged.

 

When my AC runs the condensate drips a lot but when i shut of the AC the condensate still drips but not as much. It make's me think even if you have the AC of it's still running but not flat out. Maybe like a standby mode. I noticed this more in the early spring when i had heat on at times and AC on at others. Anyone else notice their's drips even when AC is off? My bro in laws Expy does the exact same thing also.

 

The freon in the system is still cooler than the air so the condensor will still pull some water out. When running the freon is of course compressed and is much cooler and pulls more water out of the air. That would be my opinion on it. As long as you have the temperature turned to cool then the air will still pass thru the cooling coils. When you turn the temperature up it changes the air flow to pass over the heater core.

 

OK - think I got it figured out - I did in fact manually turn off the A/C.

The manual wasn't much help, so I did a little internet searching, and found this on a Ford Flex forum:

So the system did quite a good job with the conditions I had today - 55 deg, raining, and humid - I could feel some heat on my feet (warming to the set 71 deg), and the A/C was on in the upper vents keeping the glass clean.

 

If it's an auto climate control, set the temp and forget it. Let the computer do the work for you. The A/C will turn off if the temp is below a certain point.

Did I read that right...PA was 55F today??? WOW! It's was 95F with killer humidity to boot down here in FL.

 

Also, most vehicles now cycle the AC compressor in defrost, defrost/floor, and vent/floor. So, even in auto mode, the computer may decide to turn on the compressor when directing air in those modes.

 

I'm sure you're just using it as a trade name, but I'm pretty sure no one uses Freon anymore, especially not brand new vehicles. R134a is most likely the refrigerant that is used.

 

There is alot of incorrect information in this thread! Sorry to jack it but I want to clear a few things up. Freon is a trade name. The difference is R-12 is a member of the CFC (chlorofluorocarbon) group of refrigerants and R-134A is an HFC (hydroflourocarbon) group of refrigerants. R-134A has zero ozone depletion potential and this is why it has been implemented!

Now every automobile that I know of uses a Vapour Compression Refrigeration system! They consist of four essential parts:

#1-A compressor
#2-A condenser and reciever
#3-An evaporator or cooling tank
#4-Connecting piping and a regulating valve

The condenser is located in front or behind your radiator under the hood and the evaporator is located in your HVAC box in your vehicle or part of the ducting for the interior. The evaporator coil is what cools the air for the interior of the vehicle. Cooler air holds less moisture and the evaporator is not only cooling the air but dehumidifying it as well! Just my two cents.

Thank You,

 

Yes you did. I moved up to PA from South Florida this year and I'm starting to wonder if it ever gets warm here seeing how it is practically summer now.

 

Good call. Glad you spelled it out. I'm also familiar with automotive HVAC systems and know that Freon is a DuPont trade name. My last post was an attempt at a nice way of saying, "nobody uses Freon anymore, it's R134a dummy!" I figured if I said something like that that someone would come out and say, "oh yeah, my 19xx ____ still runs Freon" or some nonesense like that.

 

I believe in the Auto mode the AC is always on - it acts as a dehumidifier (as you recently found out) even if it is in the heat mode...and you just manually turned it off by pushing the button. I had the Auto system in my '05 Lariat and, to date, I have never seen the AC switch itself off in the auto mode. One thing that has always puzzled me about the Ford Auto AC systems is that they are supposed to automatically switch between the recirculated and fresh air modes...yet I have never seen mine do this...all the way back to my '01 Lincoln LS Sport the OM's have claimed this to be a function of the Auto AC system and yet I have never seen it automatically switch between recirculated and fresh air (always in the fresh air mode). My BMWs have this feature and it really does work, they actually will switch to recirculated air based on sensing certain odors in the outside air as well.