# For best A/C performance. Run with headlights on.



## snowwy66 (Nov 5, 2017)

The headlights keep the charging system at 14v. The electronics seem to like 14v alternator better then 12v battery. Both fan and cooler air are more consistent. 

Also. High side pressure should be between 210 - 235. Depending on outside air temperature. As high as 250 if you live in Phoenix and parts closer to the southern border. Where temps hit 120+ on a daily basis.

You've also got the L6 for those that don't know yet. Keep the car idling when stopped.


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## Eddy Cruze (Jan 10, 2014)

I run the running lights by default, live in the Phoenix area weather pattern and have experienced no voltage or HVAC problems in 4 years?


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## ProDigit (Aug 31, 2015)

The voltage meter constantly fluctuates between 13.x and 14.x volts while driving. I don't think it has anything to do with the ac, as the AC compressor is what'll give you cool air, and that one is directly driven by the engine.

The output of the AC is so weak (at least on the first gen) that it doesn't cool any better at fan speed 3 or 4.


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## 91794 (Mar 25, 2015)

Interesting idea. It’s not impossible. I may investigate if it ever gets humid+hot enough for me to run the AC.

Another idea is to avoid integrated phone/bluetooth, since the mylink lowers fan speed for phone calls.

Or go for a nice max legal tint.


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## snowwy66 (Nov 5, 2017)

ProDigit said:


> The voltage meter constantly fluctuates between 13.x and 14.x volts while driving. I don't think it has anything to do with the ac, as the AC compressor is what'll give you cool air, and that one is directly driven by the engine.
> 
> The output of the AC is so weak (at least on the first gen) that it doesn't cool any better at fan speed 3 or 4.


It's not about the compressor. It's about ALL the electronics that make up the system. Cars don't run off 3 speed fan switch and a old fashioned cable between temp knob and water valve anymore. 

Cars also don't run at 13.x volts. They run at the lower end of 12.x volts. Off the battery. 

My car bounces around between 12.2 and 12.4

The output of the first gen is the same as just about all other model cars. Most cars on the road these days are weak. And the reason why is because the systems aren't designed to hold over 175 pressure. You need around 225 pressure. They also aren't designed to hold as much freon as the earlier 134 models. 

GONE are the days of freezing our titties off. Although I don't know what the 1234 systems are doing yet.


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## Taxman (Aug 10, 2017)

snowwy66 said:


> And the reason why is because the systems aren't designed to hold over 175 pressure. You need around 225 pressure.


Anybody who talks about high side pressures without mentioning temperature is somebody who should NOT be advising others to take his advice over the engineers who designed the system. 

You need enough pressure to condense the refrigerant at whatever temperature your condenser is at. 

Learn what subcooling is, and if the factory charge weight isn't good enough for you, charge your system to about ten degrees of subcooling, measuring the condenser temp with an IR thermometer at 2000 rpm.


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## snowwy66 (Nov 5, 2017)

Taxman said:


> Anybody who talks about high side pressures without mentioning temperature is somebody who should NOT be advising others to take his advice over the engineers who designed the system.
> 
> You need enough pressure to condense the refrigerant at whatever temperature your condenser is at.
> 
> Learn what subcooling is, and if the factory charge weight isn't good enough for you, charge your system to about ten degrees of subcooling, measuring the condenser temp with an IR thermometer at 2000 rpm.


When 134 first came out. EPA wanted certification to buy 12 or 134. Read a book. Take the test which was open book. Receive cert in the mail. 
The book said charge hi side 100 pounds + outside air temp. I always went 125. Always acheived coldest temp out the vent. 

I use a thermometer for the vents. I go with around 225 for the high. @2000 rpm. It's worked for 30 years and no issues. 
Have yet to see any mechanic use an IR on condensor. 

You can stick with your method. I'll stick with what works. But I"ll test the IR method. 

And here's a chart for comparison. But i don't go that high. Have never achieved favorable results that high. Low pressure gets high. Vents get warmer. 

AC Pressure Chart | R-134a Temperature Pressure Chart


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## ProDigit (Aug 31, 2015)

snowwy66 said:


> It's not about the compressor. It's about ALL the electronics that make up the system. Cars don't run off 3 speed fan switch and a old fashioned cable between temp knob and water valve anymore.
> 
> Cars also don't run at 13.x volts. They run at the lower end of 12.x volts. Off the battery.
> 
> ...


Odd. Perhaps specific to the 2nd gen.
The 1st gen had no real electronics connected to the ac system. 
No climate control, no compressor speed, as far as I know, not even sensors!
Voltage fluctuations had nothing to do with the ac on gen 1 cruze ac systems. Also, I never saw the voltage dip under 13.2 or so volts, unless I applied a load like the windows. Then it would dip momentarily under. But even with a bad battery, the read voltage was always around 14V.
The gen 1, like almost all other cars out there, run off the stator. Not the battery.
The battery only acts as a buffer to start the car, or capture voltage fluctuations


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## snowwy66 (Nov 5, 2017)

ProDigit said:


> Odd. Perhaps specific to the 2nd gen.
> The 1st gen had no real electronics connected to the ac system.
> No climate control, no compressor speed, as far as I know, not even sensors!
> Voltage fluctuations had nothing to do with the ac on gen 1 cruze ac systems. Also, I never saw the voltage dip under 13.2 or so volts, unless I applied a load like the windows. Then it would dip momentarily under. But even with a bad battery, the read voltage was always around 14V.
> ...


I didn't know anything about the gas saving alternators till my aunt bought a 14 chev traverse. 
I had a 12 cruze but wasn't able to keep it very long due to employment at that time. I don't know much about the gen 1's other then this forum. But I DO know ac sucked in that thing. It was more like a humidifier. 
Later on I bought a 14 Hyundai. It was a little better then the cruze but still required an extra oz. if i wanted cold air instead of somewhat cold air. It didn't have the gas saving alternator. Or the electronics that the gen2 has. 

I threw an oz in my gen2 yesterday. Hottest day of the year. It got a little colder. But then i got to thinking about how the heater worked. At 50 degrees temp would be full hot but cab only warmed slightly. AT 40 degrees or colder heater worked better and temp had to be turned down. On my commutes to home or work. So that got me thinking about the charging system. I threw an oz in and that made it colder. What happens when the headlights are on and voltage stays at 14V. And that made an even better effect. 

What i posted above may not be the full trick for gen1's. If those don't have the alternator. Those of us that do. It helps. At night when the headlights are on. The alternator is constantly charging around 14.5. In the daytime without the headlights. We spend most of the time running off battery.

If the gen1's don't have all the electronics the gen2's do. More power to you guys. All you guys need is proper pressure.


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## snowwy66 (Nov 5, 2017)

Taxman said:


> Anybody who talks about high side pressures without mentioning temperature is somebody who should NOT be advising others to take his advice over the engineers who designed the system.
> 
> You need enough pressure to condense the refrigerant at whatever temperature your condenser is at.
> 
> Learn what subcooling is, and if the factory charge weight isn't good enough for you, charge your system to about ten degrees of subcooling, measuring the condenser temp with an IR thermometer at 2000 rpm.


I got 71.4 at the condensor for fan kick on. 67.6 fan shut off. 

It doesn't tell me what the pressures are. Or what the pressures should be. I"m pretty sure the temp would be the same if i left the pressures alone. There's too many variables that can play a part in the temp of the condensor. 

What you mention is not an effective method. And wouldn't help most of the people. Temps can vary greatly. And according to subcooling. There's more to it then just measuring the condensor. And most cars can't even get to the recommended points to measure. They're covered up with other parts. 
Is the sun shining or is it cloudy. Outside temp warm or hot. Amount of pressure can change temp. Is the fan running or off. Is there blockage in the system. Is there air in the system. 

Having the proper pressure is VERY important in having a properly functioning ac. That can't be accomplished by measuring the temp of the condensor. 

Obviously gauges are needed in adding freon. Subcooling could be a very handy tool. But just measuring the temp of the condensor. Doesn't do anything. 
Knowing what the pressure needs to be. DOES. And is also used for diagnosing problems. 

There's lots to understand about air conditioning. But this isn't a school with time for training. 

What I've posted. Is a basic procedure that everyone can understand. It's plain and simple and doesn't require any rocket science. It doesn't get anyone in to trouble. It's the most commonly used procedure. 
I've charged 100's of cars in my lifetime. And still do it. EVery month I meet the people at the park. And donate my 30 lbs. of freon. For those that can't afford to have their cars looked at. I don't do repairs. I'm retired. But those that are working properly and only need a top off. Get it. Using the same procedure I've always done. The same procedure i use for my own personal cars. AND THEY'RE HAPPY.


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