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I have a KIA Optima 2012 SX. When I drive the car for a while with the AC on, it stop blowing cold air. The only way to remedy it is to stop and restart the engine. Another situation when this happens is when stopped (at a traffic light or drive-thru etc.) but this is remedied by moving again. Living in Phoenix where it's very hot in the summer (114 yesterday :( ), having this behavior is a miserable experience. This issue only happens when it's hot outside. I've never experienced it at night. Any suggestions would greatly be appreciated.
 

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10 Optima LX, 07 Rondo EX, 89 Chevy C1500
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Check that the radiator fan is plugged in. I have seen the connectors look like they are connected but when pushed together, they give that final "click" and then the fan starts working. Check that 1st, and if it isn't the issue, contact your dealer.
 

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2011 Optima LX M/T
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Another situation when this happens is when stopped (at a traffic light or drive-thru etc.) but this is remedied by moving again.
I have this problem, as well. It's been happening ever since I bought the car new, and I live in Dallas, so I'm also subjected to stop and go traffic on 100+ degree days. When I first got the car, I noticed the problem and took it in to the dealer to look at. They recharged the coolant but said they couldn't see anything wrong with it.

I have been wondering if the radiator fan isn't spinning up when it should, since the A/C cools right down if I get rolling. I fiddled with the plug but didn't notice anything out of order.
 

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2012 sonata, 2011 Optima
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Hi,
Your (our) A/C cooling problems are inherent to the a/c coolant used, 134a. It has poor heat exchange performance at low engine rpms.
There is no question that R12 performs better than R134a, but by how much? According to statistics, for an R134a system to have comparable performance to R12, the condenser must be increased by 30%. That is a huge feat. I am not sure whether that correlates which stating that it performs 30% worse when in the same systems, but one can make a pretty good judgment that if it requires 30% greater surface area to meet prior performance, it is safe to say R12 or CFC-12 is far superior.

Overall, HFC-134a requires a larger condenser capacity and increased airflow to keep system pressures within safe regions. Increased airflow is the key. Under the hood of a Optima it is pretty tight as compared to-say a pickup. When idling the 134a circulates slowly and the heat exchange is not very efficient. OptimaDream wrote his a/c cools right down if he get rolling. Better cooling due to rpm increase and more air flow due to driving down the road. A temporary part fix is while stopped at a light is to shift into neutral and increase the engine rpms to around 1500. The 134a circulates faster, does the heat exchange quicker. Downside is you will use more fuel.
If your radiator fan is not spinning fast enough the engine would run much hotter at an idle.
Per federal law we are stuck with 134a. On those hot Phoenix AZ days I just shift into neutral and raise the engine rpms. Cools better; though not as well as using increased air flow with steady driving.
Install and aux. radiator/condenser fan? Don't recommend it. Another fan can actually inhibit the on the road air flow/heat exchange.
 
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