Kia Optima Forums banner
1 - 20 of 22 Posts

·
Registered
2012 Black SX Prem. & Tech.
Joined
·
2,528 Posts
Discussion Starter · #1 · (Edited)
After almost 11 years my air conditioner still feels cool. But I don't remember if it's as cold as it could be, like when I first got the car.

I figure, over time, surely some refrigerant leaked out and probably my air could be colder.

But everything I see says you need to just evacuate the whole system, and then add exactly the right weight of refrigerant and lubricant/oil.

Is there any way to perhaps check the high side and low side pressures, and then consult a lookup table for the ambient temperature, and see if my pressures are too low and need more refrigerant?

EDIT: Also I have an infrared thermometer gun that I could use to check the temperature of the air vents. But I worry how meaningful that would be, because it would depend on the ambient temperature as well (like I don't care if it reads 35 degrees cold air coming out of the vent if it's already 32 degrees ambient temperature). But maybe there is also a lookup table to know what the output vent air temperature should be for any given ambient temperature?
 

·
Registered
2011 Kia Optima
Joined
·
4,085 Posts
First, refrigerant doesn't leak out of the system, if it's low there's a leak.
As you stated, the only sure way is to discharge and charge at the required weight 19.3 oz, but in lieu of that,
get a R134A chart and check what the pressures should be at a given temp/humidity, a/c on max @ 1500 rpm.
That will get you close enough.
 

·
Registered
2012 Black SX Prem. & Tech.
Joined
·
2,528 Posts
Discussion Starter · #3 ·
if it's low
How can I determine if it's low?

I simply don't remember how cold the air coming out should feel. It feels cool, but I don't know if it was colder, and I'm pretty sure that it was colder ten years ago. I'm not aware of any leaks.
 

·
Registered
2011 Kia Optima
Joined
·
4,085 Posts
Gauges would give you an indication of system activity, but you can get a stick thermometer and place it in the center outlet.
From what I found, rule of thumb:
70 degrees 20% humidity 35-40 degrees
80 degrees 90% humidity 45-50 degrees
Another:
70 degrees 27-38 degrees
80 or 90 degrees 35-48 degrees

Mine was actually colder than the first example, so later today if we go out, I'll check.
 

·
Registered
2011 Kia Optima
Joined
·
4,085 Posts
Boy, am I glad I offered to take a reading when I went out. Started up the Optima, down long driveway onto the road, no air, drove maybe a mile, no air, so back home. Took it up to the back garage and threw on the gauges to check high side, to make certain it wasn't spiking and cutting out the compressor, well at 120 psi, that surely isn't the problem. Just junk!

Took the wife's Acura, now understand, the car is garaged so when starting out the A/C wasn't on recirculate, nor high fan, and didn't want to go through the
manual adjustments, or lower the temperature, so here's the reading when driving on the highway, 96 degrees ambient temp, 40 degree center vent temp.
Assume, recirculate and on high, the temp would be lower.

Hope this helps.
 

·
Registered
2012 Black SX Prem. & Tech.
Joined
·
2,528 Posts
Discussion Starter · #6 ·
Thanks, sorry to hear, and bad luck seems to be contagious. I took my infrared thermometer gun to measure the temperatures, and my gun proceeded to break and I had to throw it out.

I'm digging up the temperature probe for my multimeter and once I find that I'll get a temperature reading.

But do you know if there is a chart that tells you what the low side pressure and the high side pressure should be (accounting for ambient temperature/humidity) when the system is filled with the proper amount of refrigerant for a 2012 Kia Optima SX?
 

·
Registered
2011 Kia Optima
Joined
·
4,085 Posts
Just so everyone knows that the above figures are just, at least to me, arbitrary temps at the vent. In my example with the wife's Acura, it was 96 degrees, 75% humidity, 40 degrees at the center vent and remember, the system wasn't even on recirculate/high. In the chart, the vent temp should have been @ 61 degrees, quite a difference.
My advice to anyone having a problem is to check the pressures, and if charge is needed when or if the system needs to be recharged go by weight to avoid an over or under charged condition.
 

·
Registered
2012 Black SX Prem. & Tech.
Joined
·
2,528 Posts
Discussion Starter · #9 ·
if the system needs to be recharged go by weight to avoid an over or under charged condition.
Is there a way to find out how much weight to add to a system that needs to be recharged, like just add more refrigerant to the existing undercharged system?

So far my understanding is there is no way. Even if you know the pressures and ambient temperature and humidity, you can only tell whether the pressure is low and needs to be recharged, but you can't figure out how much weight to add to top it off. Is that right?

If that's right, then your only recourse is to evacuate the system entirely, then refill with the proper weight of refrigerant and lubricant (should be indicated on the label under the hood). But I'm not sure if that's true because maybe there is a way to top off a system. I'd love to be able to figure out how low my system is and how much weight of refrigerant I need to add to top it off.

According to Scotty Kilmer's crazy videos (I don't fully trust or agree with him) he says that the A/C compressors by design will leak over the years so that around 10 years you probably can benefit from having a full amount of refrigerant. He says the compressor's seal on the shaft by design leaks a tiny bit to ensure that the lubricant in the coolant will keep the seal lubricated. If the seal didn't leak a little bit, the lubricant would not get on the seal and the seal would dry up and fail after several years. So by design the leakage over the years keeps the seal from failing, but you will see decreased cooling performance after like 10 years. I'm not certain that's true but it sounds like a reasonable explanation where you have a rotating shaft and a seal it will probably leak at least a little bit over a decade?
 

·
Registered
2011 Kia Optima
Joined
·
4,085 Posts
We have a different point of view as from my experience, the only time refrigerant leaks out of a system is when there is a faulty part, if the seal leaks, it's faulty.

You are correct, no way to determine the amount of refrigerant that is needed if undercharged, go by gauges.
When I charge a system I use a refrigerant scale (oz) so that I know the correct amount is added.
 

·
Registered
2012 Black SX Prem. & Tech.
Joined
·
2,528 Posts
Discussion Starter · #11 ·
Yes, I believe you, as you have been reliably accurate in everything you say, unlike Scotty Kilmer who I've noticed will say things that just aren't true.

I was able to insert my multimeter temperature probe in each front vent while cruising with A/C set to recirculate and "LOW" (there is no such thing as a "max" setting that I can find on the 2012 SX. You just dial down the temperature until the number temperature switches to the word LOW).

Outside, the ambient was 90 degrees, not sure what humidity. The vents were around 40 at the two center vents, and around 43-45 at the outer vents. So I guess my system is still running strong and performing as it should. So I'm not going to recharge it. I just never measured the temperature before, but that seems like a good way to confirm proper operation. When I did the old hand test a while back, the air warmer than this, the car had been baking in the direct sunlight on a 95 degree day, so driving it I didn't drive very long and the vents just felt cool but not cold. But for yesterday's test where I measured the temps, the car was sitting in the shade and the ambient temp had dropped to 90, so the vents felt cooler and I was able to achieve 40 degrees.
 

·
Registered
Joined
·
9 Posts
See also this thread.
There's a problem where the compressor goes bad in a way that gives you cold air while moving, but not when you're stopped/idling. Apparently an internal valve failure. It may be that you have a good refrigerant charge, but a dodgy compressor.
 

·
Registered
Joined
·
68 Posts
Ok, let's start. don't use vent temp for ambient air temp! it means outside air temp ! you don't have to know how many oz. you have. you just put in enough that the low side is in range at 2000 rpm. never think more is better it is not . if you read a low side gauge you will note that the pounds of pressure are also the temp. the low side it. so if the low side is high. too much free-on, then the temp out the vent will be higher. So just be sure the low side is in the range of the chart its that easy! Use to high side only if you have a problem then read the high side to help pinpoint the problem.
 

·
Registered
2011 Kia Optima
Joined
·
4,085 Posts
Ok, let's start. don't use vent temp for ambient air temp! it means outside air temp ! you don't have to know how many oz. you have. you just put in enough that the low side is in range at 2000 rpm. never think more is better it is not . if you read a low side gauge you will note that the pounds of pressure are also the temp. the low side it. so if the low side is high. too much free-on, then the temp out the vent will be higher. So just be sure the low side is in the range of the chart its that easy! Use to high side only if you have a problem then read the high side to help pinpoint the problem.
First question, how would one know what is more if not going by weight?
Second observation, PSI is also the temp, totally incorrect. I can see high 30's when 90-95 degree ambient temp, not the 50-55 low side pressure.
Better stop printing bad information. It may work for you, but a lot more to having the A/C system work efficiently than adding gas by estimate.
 

·
Registered
Joined
·
68 Posts
First question, how would one know what is more if not going by weight?
Second observation, PSI is also the temp, totally incorrect. I can see high 30's when 90-95 degrees ambient temp, not the 50-55 low side pressure.
Better stop printing bad information. It may work for you, but a lot more to having the A/C system work efficiently than adding gas by estimate.
Well Turbonut I don,t print bad information son.The more wight you put in the pressure goes up. do you understand that? When you tell me I better stop printing wrong info on this is a little touchy for me on this subject you did not understand what I am saying. What I mean is on the low side and high side of a gauge it reads in pressure and Fahrenheit. look at your gauges! so 30 pounds=30 Fahrenheit when at 2,000 rpm is a good charge also use the ambient temp chart with that. Just look on all gauges it says that so charge low side to 28-32 pounds or 30 Fahrenheit also using the ambient temp chart and you are good to good to go! unless a/c has a different problem. I've been charging a/c for 36 years as a Toyota master mechanic.I have changed over 500 a/c auto and home. you don't have to weigh it. You can weigh it if you want but you don,t need to. Is a waste of time to me. I think I may know a little more than you. Type my last name in a google search. History of Herrick Labs if you are not sure that I know what I am saying. My family goes way back in Refrigeration we also made the first early iceboxes. if you need to know something ask I can help you.
I only go on Optima Forums to help people out or to ask for myself sometime. And I really like my 2012 Optima I lot.So much my wife is getting jealous
 

·
Registered
2011 Kia Optima
Joined
·
4,085 Posts
Well buddy, don't have the slightest idea at what you are saying, so maybe I do need some education.
Let's take 90 degree ambient temp, low side 45-55, outlet temp in the 30's, so using psi where does any
temp equal psi?
 

·
Registered
Joined
·
68 Posts
Well buddy, don't have the slightest idea at what you are saying, so maybe I do need some education.
Let's take 90 degree ambient temp, low side 45-55, outlet temp in the 30's, so using psi where does any
temp equal psi?
Yes the reading are right above just go with 45 not 55 on the low side and it will be cooler.but to be real the air coming out the vents will not be 30f more like 45-55. it will be close to 5 degrees cooler out the center vent if you did at that setup.Look on the gauge's temp is the same as the pressure.55 f. on a 90f. day the air would fell nice and cold. Do you see that on the gauge? that's what I was talking about.so you want the low side to be low like 40 to 45 not 55 at 90f. you have that right. the biggest problem with charging a/c is overcharging. more is never better in a A/C. also moistures changes things. So in calif on a 60f day charge it 30 on the low side and you will be good. what they meant on the temp on the gauge is the inside the a/c unit. The low side the temp at the expansion valve and high side it the temp at the compressor not what you measure outside coming out of vents. because the time in come out the vent it warm up some from the warm car.
I got one for you. I think the a/c compress comes on even it the a/c light is not on have you notice that?
 

·
Registered
2011 Kia Optima
Joined
·
4,085 Posts
Yes the reading are right above just go with 45 not 55 on the low side and it will be cooler.but to be real the air coming out the vents will not be 30f more like 45-55. it will be close to 5 degrees cooler out the center vent if you did at that setup.Look on the gauge's temp is the same as the pressure.55 f. on a 90f. day the air would fell nice and cold. Do you see that on the gauge? that's what I was talking about.so you want the low side to be low like 40 to 45 not 55 at 90f. you have that right. the biggest problem with charging a/c is overcharging. more is never better in a A/C. also moistures changes things. So in calif on a 60f day charge it 30 on the low side and you will be good. what they meant on the temp on the gauge is the inside the a/c unit. The low side the temp at the expansion valve and high side it the temp at the compressor not what you measure outside coming out of vents. because the time in come out the vent it warm up some from the warm car.
I got one for you. I think the a/c compress comes on even it the a/c light is not on have you notice that?
Thanks for responding, but a couple of observations. Why would I want to lower the pressure to 45 and see 45-55 degree vent temp when now, after charging by weight, have 38 degrees exit temp at 90 degree ambient temp?
Yes, overcharging is always a concern, so to avoid that possibility, why not charge by weight and no need for the possibility of an overcharged condition?
I also agree that not only the ambient temp, but the humidity plays a part in the correct charging pressures, so once again, why not just charge by weight and be done with any guesswork that needs to be done?
I just put the tank on a scale, fill by weight, no guessing. Even the garage equipment, set parameters, start and the machine will do it all by weight, both refrigerant and oil, and you'll be able to see amount of each that's been removed, then know if it were low on charge and/or low on oil. Then, just set the refrigerant & oil requirements, sit back and let the machine do it's job, easy and no guesswork required.

There's no doubt the system can be charged using gauges as a reverence, done it many times, still miss the old sight glass, but to nail it dead on, no substitute for charging by weight, can't go wrong.
 
1 - 20 of 22 Posts
Top