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When the car is at idle (stop light or stopped traffic) the AC while blowing there is a significant change in the temp of the air. Once I start to accelerate the air starts to blow cold. Anyone run into this before?
 

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When the car is at idle (stop light or stopped traffic) the AC while blowing there is a significant change in the temp of the air. Once I start to accelerate the air starts to blow cold. Anyone run into this before?
YES, and I believe I have the solution that will help a lot of people. . . .

Backstory first. I own a 2012 Sonata SE 2.0T with 103k miles, purchased new. It's been a great car, with very few problems other than typical wear and tear issues. The biggest nuisance has been the fact that even when it was first just a few years old, the AC would cool the car poorly when stopped, then would resume effectively cooling when the car would start moving again.

Just before the car was out of the bumper to bumper warranty, I took the car to the dealership we purchased it at, and demanded something be done. Of course, they balked, insisting that the AC works as intended BECAUSE THEY ROAD TEST IT ON THE HIGHWAY WHERE OF COURSE IT WOULD FREEZE YOU OUT. I've been friends with the service department manager for a long time, so I insisted they do SOMETHING. My observation was that the cooling was weak at low vehicle speed (irrespective of engine speed) so I pressed for replacement of the radiator/condenser cooling fan motors. I don't know if they actually replaced anything, but they said they did replace the fans AND clean the condenser. They didn't elaborate, but the service cost me nothing thanks to warranty, and the AC did work better, at least for a time.

Fast forward a few years. This is my wife's car that she drove pretty much every day. She started complaining again that the AC wasn't working well, and I told her I'd take a look at it. She announced one day that she was going to start driving my Lexus instead, because she could no longer stand to "drive a car with no AC." Rolling eyes. . . . Her statement is based on the fact that in Austin traffic, most of the time you're crawling along less than 20 MPH. I allowed her to drive the Lexus, and started driving the Sonata myself most of the time while I'm in town and discovered first hand how bad the cooling had gotten.

So, knowing the car doesn't run hot, and cools great going down the road at 40 MPH or more, I knew it had to be a matter of heat removal from the condenser. I had tried to spray water through the condenser with a garden hose, but found that the design of the grille prevents effective application of a spray nozzle. I found a video on YouTube showing how to remove the grille insert (without removing the entire bumper cover assembly, which by the way is ABSOLUTELY the right way to do it and easier than you'd think.) Once the grille insert was out, I got busy with the garden hose and nozzle and sprayed as much of the condenser through as I could access, roughly the top half of the condenser. I drove the car for a couple days with the grille insert removed, and found that while it still cooled poorly at a stop, it was a bit better, and the speed required for effective cooling was noticeably less.

Encouraged by the improvement, I mixed up a batch of HVAC condenser coil cleaner (Nu-Calgon Nu-Brite, purchased on Amazon) that I had purchased for cleaning the outside unit on my home, and commenced to cleaning the portion of the AC condenser and turbocharger charge air cooler that I could access through the grill insert opening and from under the hood. Impressive amounts of gunk were foamed out, and after another day of test driving in 105 degree heat, I knew I was on the right path because the cooling was that much better.

Finally, I removed the entire bumper cover assembly (easier than I thought, no damage created by this effort) as well as the vertical bar crossing the condenser top to bottom in the middle as well as the plastic air deflector funneling air around the bumper and into the charge air cooler. I used that same coil cleaning product to clean the ENTIRE condenser and charge air cooler once again. I wish I'd have taken pictures, the amount of crap that came out (even from the part I had cleaned a few days prior) was shocking. I used an electric pressure washer and the 40 degree fan tip (gentlest one) to blast/rinse the cleaning chemicals through the condenser and radiator as well as the charge air cooler. The difference in appearance between before and after cleaning was pretty shocking. I was confident that there would be further improvement, and the test drive after I put the bumper back on was a good one.

Not only does the car cool well at idle now, it doesn't take forever for the cold air to start being felt when you first start up on a hot day. And moving down the road at "highway" speed, you can make air come out that's so cold it makes your bones hurt. THIS is the kind of cooling performance that one should expect from a modern automotive HVAC system. THIS is the kind of cooling that my Lexus provides, but it's got a lot fewer miles on it. . . . but I may do the same thing on this and my other cars as preventative measure.

Why don't the dealerships do this? Is it ignorance of thermodynamics (very likely.) Is it because they don't make money unless they change parts? I'm pretty sure it's a combination of the two, more likely the later. It took me maybe fifteen minutes to remove the bumper cover assembly, maybe five minutes to remove the bar that goes across the core support and the "air funnel" on the charge air cooler. Three minutes to carefully apply the cleaning chemical to the condenser, CAC, and what little part of the radiator was visible around the top of the condenser. Ten minutes dwell time to let the cleaner foam the gunk up and lift it away. Another ten minutes spent blasting/rinsing the chemical out of the cooling stack with the electric pressure washer, maybe another 20 minutes to reassemble everything when I was done.

The results of this effort are remarkable. I strongly recommend anyone with one of these cars or any other car that the AC "works" but cools poorly at a standstill or low vehicle speeds do this same thing. On the Sonata, watch the video I'll link below to see how the bumper cover assembly comes off. On any other car, take a minute to search on YouTube for a video showing you how to remove your bumper cover. Then there are videos showing how to clean the condenser coil (not Sonata specific, but you'll get the idea.) The cleaning chemical is available online, and I think you can buy spray cans of the same or similar stuff at Home Depot or Lowes. You can drive the car legally without the bumper cover on, because the lights all stay in place and function, so you can do the actual cleaning at a coin operated car wash. The only issue you might have, is if you remove the bar across the condenser as I did, you will also remove the hood latch (don't want to drive without this, your hood WILL open up.) You can probably get 95% of the benefit leaving that bar in place. DO make sure you rinse VERY thoroughly because these cleaning products are caustic, and will cause the condenser and radiator to corrode if not completely removed. I've seen it suggested to spray a weak solution of water and vinegar into the cleaning stack to help ensure the cleaner (alkaline) is neutralized.

Link to video showing Sonata bumper removal:

Link to video showing cleaning of AC condenser on a car:

Big Thank You to the folks who made these videos. I suggest you all take a look at this and give it a try. At the very least, watch the videos (and give them thumbs up, big way to show folks you appreciate their content.)
 
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