WTF does Max A/C do?

101lifts2 · 07-17-2011, 02:38 AM

Quote:

Originally Posted by RedRider2k2

I know this is an old ass thread but...

I've service/repaired a lot of AC systems and I've never seen one like this. Running the compressor 100% will just flood/freeze up the Evaporator.

Yes, that is because he doesn't know wtf he is talking about.

Max A/C is for cabin air recirculation only. Notice when you have a Recirc button, you don't have a Max A/C setting. When you have a Max A/C setting, you don't have a recirc button.

Most compressors nowadays don't cycle anyway. They are either ON or OFF. The pressure control is done with valving in the compressor itself. This is not to say that the engine controller cannot turn OFF the compressore if the high side pressure becomes too high or too low or if you in a W.O.T. scenario.

Particle Man · 07-17-2011, 03:15 AM

Quote:

Originally Posted by 101lifts2

Yes, that is because he doesn't know wtf he is talking about.

Max A/C is for cabin air recirculation only. Notice when you have a Recirc button, you don't have a Max A/C setting. When you have a Max A/C setting, you don't have a recirc button.

Most compressors nowadays don't cycle anyway. They are either ON or OFF. The pressure control is done with valving in the compressor itself. This is not to say that the engine controller cannot turn OFF the compressore if the high side pressure becomes too high or too low or if you in a W.O.T. scenario.

My Kia has both a max and a recirc setting. I can recircate the air on every setting. When "Max" is selected, I can't override the recirculate feature.

The Subaru only has the recirc button and no "Max" setting.

Rangerscott · 07-17-2011, 11:33 AM

Quote:

Originally Posted by Particle Man

My Kia has both a max and a recirc setting. I can recircate the air on every setting. When "Max" is selected, I can't override the recirculate feature.

The Subaru only has the recirc button and no "Max" setting.

Same with our work '04 F-150. The only thing is max a/c just blows through the top vents. I always have it set to top/bottom and hit the recurculate button.

azoomm · 07-17-2011, 03:21 PM

Quote:

Originally Posted by 101lifts2

Yes, that is because he doesn't know wtf he is talking about.

Max A/C is for cabin air recirculation only. Notice when you have a Recirc button, you don't have a Max A/C setting. When you have a Max A/C setting, you don't have a recirc button.

Most compressors nowadays don't cycle anyway. They are either ON or OFF. The pressure control is done with valving in the compressor itself. This is not to say that the engine controller cannot turn OFF the compressore if the high side pressure becomes too high or too low or if you in a W.O.T. scenario.

I have both MAX and re-circ on my 1-Series. Actually, I have MAX and three settings to recirculate air. If I select MAX it drops the selected temp to 60 and does a full lockout to recirculate the air. The MAX selection also locks out the passenger's ability to select their own temp. I'm still trying to figure out the three settings on re-circulation. I might have to RTFM

fasternyou929 · 07-17-2011, 04:24 PM

Quote:

Originally Posted by 101lifts2

Yes, that is because he doesn't know wtf he is talking about.

Max A/C is for cabin air recirculation only. Notice when you have a Recirc button, you don't have a Max A/C setting. When you have a Max A/C setting, you don't have a recirc button.

I couldn't have come up with a better rebuttal. Thanks for talking out your ass and saving me the time.

101lifts2 · 07-17-2011, 09:03 PM

Quote:

Originally Posted by fasternyou929

I couldn't have come up with a better rebuttal. Thanks for talking out your ass and saving me the time.

Dude I'm a service engineer for a car company...and have worked with car companies since I was 22. If I know anything in this world...it's cars.

You guys just guess at shit...or try to analize things using general common sense. Your original statement that the compressor cycles because of "Max A/C" or "Normal" just is not true.

Those that have Max AC and a Recirc button is simply for air venting direction (Max AC) and then % outside air using the Recirc button.

fasternyou929 · 07-17-2011, 11:31 PM

Quote:

Originally Posted by 101lifts2

Dude I'm a service engineer for a car company...and have worked with car companies since I was 22. If I know anything in this world...it's cars.

You guys just guess at shit...or try to analize things using general common sense. Your original statement that the compressor cycles because of "Max A/C" or "Normal" just is not true.

Those that have Max AC and a Recirc button is simply for air venting direction (Max AC) and then % outside air using the Recirc button.

So two decades in the industry and you think GM builds a quality product and think cars have either a Max AC button OR recirculate. And I'm the one that doesn't know what he's talking about.

All cars I've driven have both. All cars I own kick on the auxiliary cooling fan as soon as Max AC is selected. Observation skills bordering on retarded should still allow you to at least gather that if cars have been your life for 22 years. If I was wrong about the compressor, so be it, I'm not opposed to learning from someone here. Provided they at least come across as knowledgeable, beyond just claiming to be while regularly showing otherwise.

101lifts2 · 07-18-2011, 01:21 AM

Quote:

Originally Posted by fasternyou929

So two decades in the industry and you think GM builds a quality product and think cars have either a Max AC button OR recirculate. And I'm the one that doesn't know what he's talking about.

...

It doesn't matter that is SAYS MAX AC, what matters is what it does. FWIW, my 2011 Mazda 3 has both, but the MAX A/C does nothing but ensures that the Hot/Cold is all the way to the full Cold. The condensor fan runs whenever the A/C is turned on regardless if it is all the way to the Max AC position. The Recirc button does just like it says. Recirculates. Why they even put "Max A/C" I can only guess is so the clueless don't leave it still in the "blue", but not all the way in the full blue range. Ford, GM and Chrysler always used only Max AC, which forced recirculation.

Quote:

...All cars I own kick on the auxiliary cooling fan as soon as Max AC is selected......

Well, apparently you have not driven a GM, VW or Mazda because they don't. The A/C fan on all GM vehicles was always a function of the A/C relay ON and A/C high side pressure. I would be that Max A/C does not even have a signal to the body controller. My Mazda 3 runs the A/C fan when the A/C is on and the A/C high side pressure is above a certain threshold. Max AC is not any type of input.

So now the question remains....do you have BOTH a recirc. button AND a MAX A/C button? Or do you have a Recirc button and lettering that says Max A/C because then Max AC doesn't do anything.

I should have said that Max AC acts as a recirc function if you don't have a button. If they put both there, the MAX AC is only to make sure you put it to full cold.