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2011 Kia Optima
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Discussion Starter · #1 · (Edited)
Just thought I'd post an update on the crappy A/C system in these cars so one might have an idea what to expect when the A/C decides to go south..
Purchased '11 2.0T in 2016 with 108k miles, but at 118,000 the A/C started to act up. Typical cold air delay after start up, maybe 2 minutes, maybe 5 minutes, maybe longer, no cold air at idle, until one hot/humid day it decided not to work at all. As the compressor was making noise decided to go with a used compressor rather than just change the electronic control valve. Compressor ($60) had 23,000 miles, did the install no problem, but now with 94,000 miles on the compressor same crap once again. Received the new valve yesterday, did the install today, back to normal, cold air at startup, cold air at idle, so guess we'll see how long this one lasts.

Thought I'd also add, that if the valve does need replacement, the a/c system needs to be discharged, remove wire from valve,remove snap ring, remove
valve, I put some Pag 46 oil on the new valve, install valve and snap ring, connect wire, evacuate system, charge 19.3 oz R134a.
 

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2013 Kia Optima
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557 Posts
I had a similar issue, and figured out that mine was running overpressure, up near 60 or 70 PSI. I vented it completely, and refilled it to 40PSI using the STP high end stuff, and that seems to have cured it... It now blows cold at startup, which it wasn't doing before, and stays cool all the time. Ambient temp at time of measurement was 80F.
 

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Discussion Starter · #4 ·
I had a similar issue, and figured out that mine was running overpressure, up near 60 or 70 PSI. I vented it completely, and refilled it to 40PSI using the STP high end stuff, and that seems to have cured it... It now blows cold at startup, which it wasn't doing before, and stays cool all the time.
First I've seen this, but just for the folks, low side pressure is determined by ambient temp and humidity, not always 40 psi.

Hey Turbonut, when you going to buy another Optima? 😁
Last week, just sold the '08 Optima we purchased new, 293,000 miles, and even with the outrageous returns in the market, looks like I'll hang on to the '11 for some time, especially with the new engine. Was centering the steering wheel on the wife's Acura TL yesterday and can't believe, minimal play in the LF wheel bearing, so looks like I'll be changing that when she returns from the shore. Had the RX7 Turbo out on Saturday, made it a 1/2 mile and the clutch pedal went to the floor, so back to the garage and Monday changed the clutch mc, hose and slave cylinder, then out for a ride Monday night.

Actually find it very aggravating working on cars anymore, but it's a necessity as I can't stand to pay someone that does a crappy job and charges an exorbitant amount of money.
 

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Discussion Starter · #6 · (Edited)
Fixed earlier entry, temp at time of measurement was 80F.
(y)

Ambient Temperature (°F)Low SideHigh Side
110°50-55 psi335-345 psi
105°50-55 psi325-335 psi
100°50-55 psi300-325 psi
95°50-55 psi275-300 psi
90°50-55 psi250-275 psi
85°50-55 psi220-250 psi
80°45-50 psi175-220 psi
75°40-45 psi150-175 psi
70°35-40 psi140-165 psi
65°25-35 psi135-155 ps
 

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Going by that chart, I'm probably a pound or two under, Measuring it this afternoon I was at about 43 PSI, and the tempreature was about 80F, with close to 80% humidity...
 

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Discussion Starter · #8 ·
There's only 19.3 oz in the system.
In fact, some use the chart, some use that in combination with a stick thermometer in the center outlet,
but I've found that using a scale to weigh the amount being added is the way to go as it takes the guesswork out of the equation.
 
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