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2010 Kia Rio LX
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Discussion Starter · #1 ·
I live in Texas and as the heat of summer approaches I would love me some colder A/C.

Proper refrigerant capacity is a hot-button thing to DIY. So I asked around and pretty much all sources I ask say to just go by PSI. The online pros I see writing on forums say to go by weight. IE, kia specs say 2010 kia rio LX has 17oz or so 134a refrigerant. That's less than 2 cans of 12oz. Which cost ten bucks around here.

So I decided to try this theory out. Warmed up engine for 15 minutes running ac on max, pulled over and measured low-side pressure. 30psi 80f out(just after dusk). Various charts I consulted specify that is too low. So I added more and more 134a and checked my pressure in stages as I went. Coming in close to 40psi I was out of 134a in a new can. So I put in 11.5oz or so and saw 10psi bump. A/C feels colder, but no means of using thermometers was conclusive.(many varying readings)

If I had to guess the A/C is barely colder. But 11.5oz more sounds too much. I am watching the pressure carefully.

Another subject I want to touch on is insulating the aluminum piping for low-side. Some say they see some difference, some say they see a big difference. I can't find any down-side to spending some cash on foam and zip-ties. So I will report my findings once my car cools down and I wrap it. It looks like I might have to take a tire off to get to all the low-side pipe.
 

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Discussion Starter · #2 ·
Alright, seems like I solved it. I ended up getting a vacuum pump and A/C manifold. Evac'd the system to 29 vacuum, 45mins, let it sit and there were no leaks. Put in 17.95oz 134a and 3oz oil.

109f today in texas, started for home it was blowing cool(not cold), but once I hit few thousand rpm for a couple minutes it blew fridgid air. All the way home :D, even sitting at a red light 20 mins.(hate feeder road traffic)

I also put insulation on the low-side pipe, armacell foam $6.
 

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There is a sensor mounted in the evaporator that tell the control unit when to turn the compressor on and off. No matter what you do to the rest of the system, the compressor will always turn of at the same temperature. You wouldn't want that to change.
The only way to make the air colder is to try to keep it from warming up after it passes through the evaporator on its way to you.
 

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Discussion Starter · #4 ·
Like I said a hot button topic, but knowing that it has the right capacity freon now makes me happy.

The insulated low-side line yes is coming from the evap, but keeping it cool on it's way to the compressor has been said to lighten the load of heat on the system and overall cool a couple degrees.

Being that my scan tool cant pick up evap temp sensor(ECU probably does not send it), I can't confirm if evap is actually reaching the specific temp.

All that being said, it was 100+f several days this month, all of which the ac felt horribly warm until I recharged and put the insulation on low-side. Pick whatever reason you wish, but $6 for insulation I figured worth a try.

I researched around and found conflicting reports of insulation on the aluminum pipes having an effect. Those that tried it saw a temp drop measuring duct with meat thermometer. Those who claim to be certified mechanics say it wont do anything.

So by no means am I saying people go try this at home. But if you promise not to sue me your business is your own. My results may be typical, maybe not.
 

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?..knowing that it has the right capacity freon now makes me happy.
It also makes the system function properly.
I'm not trying to discount your addition to the a/c as invalid. I too, am of the opinion that if one truly believes something works...then it simply does.
Anecdotal evidence: My car always accelerates faster and handles better right after I leave the car wash. ;)
 

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Discussion Starter · #6 ·
$177 at HFT for the guage set and vacuum pump. $20 for 134a. Took me an hour. Correct freon capacity = super cold a/c. I offered my services at work for small fee to recoup the tools cost. We'll see.

Speaking of anecdotal evidence. How do we really know the electrons are flowing from positive to negative, I mean I can't see it.
 

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2010 KIA Rio LX Midnight Black.. CAI.. 6000k HID..
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Would the cheaper way be to just recharge the system and use heat wrap to cover the piping? Im not a mechanic by any means and dont have half a clue what youre saying. But my '10 LX A/C has been getting warmer.
 

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2008 Rio LX, 2007 Honda Shadow (Bike)
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The most accurate way to recharge is using a scale on an vacuumed system. That being said, with enough experience you can certainly "top off" (or charge) using gauges only. As far as the insulation on the low side line goes I can see where that might be of some help but probably very minimal. Can't hurt to try it.
 
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