How to get normal AC

[Flashflood]

On a digital climate control on my dad's 2000 limited explorer how do you get normal AC No Max

 

[tinman_72]

I had the same question and looked it up in the manual. While it did not have instructions on how to put it on normal AC, it did mention that max AC is actually the more efficient (IE cools faster and less draw on the system) than normal AC, at least on the type with the three rotary knobs. According to the manual, the advantage of normal AC is that it is quieter. I assume this would be true for any type of AC system.
Max AC pulls air from the cabin. Normal AC pulls air from outside so it has to work harder to cool and dry the air.

 

[410Fortune]

learn something new everyday

 

[fast_dave]

@Flashflood

There seems to be a misunderstanding of the design & use of auto A/C systems, and I'm going to attempt to help clear it up in short format.

In a properly charged and serviced auto A/C system (emphasis on this condition) ;

A) The Re-Circulating/ MAX setting is used to cool down a hot cabin of a vehicle that has been sitting in the sun.
It's purpose is to constantly re-circulate the cabin air over the Evaporator so as to quickly lower the cabin temperature to a comfortable level.

NOTE 1: When your A/C is operating in this mode, outside of the parameters of certain driving conditions such as Wide Open Throttle (WOT), the A/C compressor is operating almost all the time.

B) Then, once your cabin has cooled down to a comfortable level, you switch over to the NORMAL setting, so as to allow hot outside air pass over the Evaporator.

NOTE 2: The benefit of the NORMAL setting is that it takes the load off of your A/C Compressor from operating all the time.
It allows the Compressor to cycle on & off as needed to maintain a constant cabin temperature.

The NORMAL SETTING provides a COMBINATION of having the A/C Compressor cycle on/off & having hot outside air pass over the Evaporator, ensureing that the Evaporator will not ice up. This is what causes puddles of condensation to appear under your vehicle - which is normal and good - it shows your Evaporator is not icing up.

Bottom line: In a properly charged and serviced system, using ONLY the MAX setting will eventually ice up the Evaporator, which will actually decrease the efficiency of the a/c system as well as put a lot of undue wear and tear on your A/C Compressor.

In conclusion: I suggest that you continue your quest to find out how to allow outside air pass over the Evaporator on your digital controlled A/C system.

HTH -

 

[Flashflood]

@Flashflood

There seems to be a misunderstanding of the design & use of auto A/C systems, and I'm going to attempt to help clear it up in short format.

In a properly charged and serviced auto A/C system (emphasis on this condition) ;

A) The Re-Circulating/ MAX setting is used to cool down a hot cabin of a vehicle that has been sitting in the sun.
It's purpose is to constantly re-circulate the cabin air over the Evaporator so as to quickly lower the cabin temperature to a comfortable level.

NOTE 1: When your A/C is operating in this mode, outside of the parameters of certain driving conditions such as Wide Open Throttle (WOT), the A/C compressor is operating almost all the time.

B) Then, once your cabin has cooled down to a comfortable level, you switch over to the NORMAL setting, so as to allow hot outside air pass over the Evaporator.

NOTE 2: The benefit of the NORMAL setting is that it takes the load off of your A/C Compressor from operating all the time.
It allows the Compressor to cycle on & off as needed to maintain a constant cabin temperature.

The NORMAL SETTING provides a COMBINATION of having the A/C Compressor cycle on/off & having hot outside air pass over the Evaporator, ensures that the Evaporator will not ice up. This is what causes puddles of condensation to appear under your vehicle - which is normal and good - it shows your Evaporator is not icing up.

Bottom line: In a properly charged and serviced system, using ONLY the MAX setting will eventually ice up the Evaporator, which will actually decrease the efficiency of the a/c system as well as put a lot of undue wear and tear on your A/C Compressor.

In conclusion: I suggest that you continue your quest to find out how to allow outside air pass over the Evaporator on your digital controlled A/C system.

HTH -

Will do

 

[MrQ]

"Normal" is when you switch to "Vent" and set your temp below ambient. Setting "60°F" will have the compressor turn on all the time, but the external air door will be open; setting the temp between 65 and 75 tells the temperature controller that you want a definitive temperature in the cabin and it will change the blend door and compressor function to achieve and maintain that temp. Likewise if you set it to 80 it opens the blend door all the way for max heat. "Vent/Floor" and "Floor" operate the same way, but also actuates the directional door.

If you change the temp like above in "Max A/C" the external air door will remain closed and only the blend door will actuate to maintain the temperature. Setting the temperature to 60 or 80, like above, will move the blend door to it's max setting and will not attempt to maintain a temperature. Pressing "Max A/C" will set the blower to full, set the temp to 60, and turn the compressor on.

"Defrost" and "Floor/Defrost" will always have the A/C on dependent on exterior temperature to dry the air and defog your windows. It is also set to use outside air. Under a certain outside temperature the A/C will not activate and the system will attempt to use ambient air and the blend door to defrost.

"Automatic" lets the EATC handle everything once you set the temperature, meaning it will handle the blower, the air direction, blend door, defrost/defog, to maintain your desired temp. Adjusting anything outside of the temperature in this mode turns off "Automatic".

 

[koda2000]

I've owned a 1/2 dozen Explorers/Mountaineers and a Sport Trac over the past 8 years (2000's and 2001's). Most have had the automatic climate control (EATC). I live in GA where A/C is a must during the Summer months due to the high temps and humidity. I typically set my HVAC controls to MAX and leave it there for extended periods of time without suffering any ill effects. My systems are fully charged and operate perfectly. Typically I find the vehicles cycle the A/C compressor about every 8-9 seconds. My dash center vent temps run a low of 35 F to the mid 40's F. I've never had a compressor run all the time w/out cycling (regardless of setting) and I've have never had my evaporator freeze up (although that can happen, especially if the system is overcharged). Today it was in the low 90's with high humidity and I ran my Sport Trac A/C on MAX for about 2 hours highway without any issues. Super comfortable in the cabin. If I smoked I'd run the system on A/C NORMAL for ventilation (fresh air door open) once it reached a comfortable temp, but I don't smoke and I like my A/C cold. On vehicles with the automatic digital HVAC controls, if you want NORMAL A/C, turn on the A/C (blue button) and press VENT. If you find it too cold for you, increase the digital temp until you're comfortable.

 

[tinman_72]

I have gotten bad reps on other forums for posting facts so I just want to issue a little disclaimer before I post any information that seems to contradict the above information. I don't want to come off as stand off-ish so this post will only contain information directly from my Mountaineer's User Manual. I have always used MAX A/C in the past (in all my vehicles) just to cool off, then switch to normal AC. I only changed this habit after I read the following information from the manual.
My second disclaimer is that my manual does not so much as mention auto climate control. It only covers the standard AC with the three knobs. So take this information as you will. The following is directly quoted from said manual. (Items in brackets <> mean that there is a picture of the icon printed in the manual rather than a word.)

The air conditioning compressor will operate in all modes except <floor> and <vent>. However, the air conditioning will only function if the outside temperature is about 10°C (50°F) or above.
[A paragraph about how it is normal for water to drip underneath.]
Under normal conditions, your vehicle's climate control system should be left in any position other than MAX A/C or OFF when the vehicle is parked. The allows the vehicle to "breathe" through the outside air inlet duct.

• MAX A/C - Uses recirculated air to cool the vehicle. MAX A/C is noisier than A/C but more economical and will cool the inside of the vehicle faster. Airflow will be from the instrument panel registers. This mode can also be used to prevent undesirable odors from entering the vehicle.
• A/C - Uses outside air to cool the vehicle. It is quieter than MAX A/C but not as economical. Airflow will be from the instrument panel registers.

There is more but it just goes on to explain how air is directed to the floor when you turn the knob to floor, etc.
What does Ford mean by economical? I would assume that it means less work from the vehicle to produce more output. Less work, I would think, means less fuel used, less stress on the system.

 

[BTR]

Since when do the NORMAL and MAX settings directly (Note the word "directly") change the frequency of compressor cycling?

I thought NORMAL A/C only opened the vent (in order to use outside air)... and MAX A/C only closed the vent (in order to use recirculated air).

I've never heard that the NORMAL and/or MAX settings directly change the command that tells the compressor to cycle. My understanding is that compressor cycling is controlled by the A/C Cycling Switch regardless of whether NORMAL or MAX has been selected.


A/C Cycling Switch
The A/C Cycling Switch interrupts compressor operation before the external temperature of the A/C evaporator core gets low enough to cause the condensed water vapor (excess humidity) to turn to ice. It does this by monitoring low side line pressure. It is known that a refrigerant pressure of approximately 210 kPa (30 psi) will yield an operating temperature of 0°C (32°F). The A/C cycling switch controls system operation in an effort to maintain this temperature.

The A/C cycling switch is mounted on a Schrader valve-type fitting on the top of the suction accumulator/drier.

 A valve depressor, located inside the threaded end of the A/C cycling switch, presses in on the Schrader valve stem.

 This allows the suction pressure inside the suction accumulator/drier to control the operation of the A/C cycling switch.

 The electrical switch contacts open when the suction pressure drops to 152-193 kPa (22-28 psi).

 The contacts close when the suction pressure rises to 276-324 kPa (40-47 psi).

 When the A/C cycling switch contacts close, the signal to energize the A/C clutch is sent to the wide open throttle A/C cutoff relay.

 When the A/C cycling switch contacts open, the A/C clutch field coil is deenergized and compressor operation stops.

 The A/C cycling switch will control the A/C evaporator core pressure at a point where the plate/fin surface temperature will be maintained slightly above freezing.

 This prevents icing of the A/C evaporator core and blockage of airflow.

 

[koda2000]

Since when do the NORMAL and MAX settings directly (Note the word "directly") change the frequency of compressor cycling?

I thought NORMAL A/C only opened the vent (in order to use outside air)... and MAX A/C only closed the vent (in order to use recirculated air).

I've never heard that the NORMAL and/or MAX settings directly change the command that tells the compressor to cycle. My understanding is that compressor cycling is controlled by the A/C Cycling Switch regardless of whether NORMAL or MAX has been selected.


A/C Cycling Switch
The A/C Cycling Switch interrupts compressor operation before the external temperature of the A/C evaporator core gets low enough to cause the condensed water vapor (excess humidity) to turn to ice. It does this by monitoring low side line pressure. It is known that a refrigerant pressure of approximately 210 kPa (30 psi) will yield an operating temperature of 0°C (32°F). The A/C cycling switch controls system operation in an effort to maintain this temperature.

The A/C cycling switch is mounted on a Schrader valve-type fitting on the top of the suction accumulator/drier.

 A valve depressor, located inside the threaded end of the A/C cycling switch, presses in on the Schrader valve stem.

 This allows the suction pressure inside the suction accumulator/drier to control the operation of the A/C cycling switch.

 The electrical switch contacts open when the suction pressure drops to 152-193 kPa (22-28 psi).

 The contacts close when the suction pressure rises to 276-324 kPa (40-47 psi).

 When the A/C cycling switch contacts close, the signal to energize the A/C clutch is sent to the wide open throttle A/C cutoff relay.

 When the A/C cycling switch contacts open, the A/C clutch field coil is deenergized and compressor operation stops.

 The A/C cycling switch will control the A/C evaporator core pressure at a point where the plate/fin surface temperature will be maintained slightly above freezing.

 This prevents icing of the A/C evaporator core and blockage of airflow.

I agree with what you've stated above with one small caveat. When in MAX mode the heater control valve is closed, preventing hot coolant from circulating thru the heater core in an effort to eliminate any hot air from mixing with the cold (which can happen to a small degree even though the blend door is closed). In NORMAL A/C mode the heater control valve remains open allowing you to control the air temp while still having A/C.

In A/C Max mode the EATC system's the digital display indicates 60 degrees. IDK what happens if you increase the temp setting to say 70 degrees in MAX mode. Does the fresh air door remain closed? Obviously the heater control valve must be opened, in this case are you still actually in MAX mode? I've never tried this, because it seems ridiculous to me to run on A/C MAX and want heat at the same time. Frankly I don't care for the Electronic Automatic Temperature Control system as when I want cold I want cold and when I want hot I want hot and the manual 3-knob controls work fine for this purpose.

As far as the "facts" about how the system works, while I've read what my owner's manual says (and believe I have a pretty good understanding of how A/C systems work in general) I mostly go by what I've experienced driving 10's of thousands of miles of driving in multiple Gen II Explorers.