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2009 KIA Sedona LX, 2006 Hyundai Sonata 2.4 GL
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145 Posts
Discussion Starter #1
Does anyone else have an issue with their air conditioning and headlights dimming. I just noticed it with mine 2-3 weeks ago and when ever the A/C starts the lights dim so that it's noticable even when driving at 100km/h.

I just got back from the dealership and they tested my alternator and with the tools they have it's all normal. The one other test he would have liked to do if he could was load test the alternator. He (the tech) told me he doesn't have that equipment to run an amperage test. He is going to call KIA and ask them if they have had any issues with it and then get back to me when they find out.

The part that concerns me is that the issue was not there a few weeks ago but is now. If it were only doing it at idle I would also not be too concerned but as I said it's while driving.

Has anyone else had this issue and if you have what if any fix was applied?
 

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2003 Kia Sorento
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606 Posts
Well, when you turn the A/C on, you're putting quite a load on the alternator. You're right, dimming the lights at idle wouldn't surprise me, but it's pretty amazing that they dim, and you notice it, at speed. Do they dim a lot? Or are you just paying really close attention?

Check your battery cables and make sure they are tight. Did the tech run any tests on the batery?
 

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2009 KIA Sedona LX, 2006 Hyundai Sonata 2.4 GL
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145 Posts
Discussion Starter #3
I don't think so. All I know is he checked the amount of voltage going to the battery and said all numbers were within the KIA specs.

The only reason I even took it in was the at speed part. I notice it alot and not just because I am paying attention. But of course now that I am paying attention it seemd all too often.
 

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2005 Sorento ex v6 automatic
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537 Posts
i noticed when i have the a/c on, but only when the radiator/condensor cooling fans come on, the blower motor inside the vehicle slows down (this never happened with the 97 merc/sable we had)

in our case the battery seems ok (but is it correctly rated at 70 amp/hrs)

it is also possible the the altinator, although it is reasonbly as to amp output it may not putout as many amps at lower engine rpms as someother mfg's of altintors

as far as driving at night with the a/c on...i rarly drive after dark

today i will run some voltage checks and let you know what i find
 

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2005 Sorento ex v6 automatic
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537 Posts
lights dimming when A/C comes on,

i was just out checking our sorento. i did a number of voltage tests. none of them out of the normal (i got just what what i expected)

i have been a mechanic for 33 years and understand batteries and charging sytem very well

our sorentos have two electric radiator/condensor fans and they have two speeds (low and hi)

these fans draw lots of power at hi speed and if your are idling at appx 750 rpm (in gear) the alt may not supply the power necessary to run all the electric items using power in your vehicle, so it now draws from your battery and brings down the vehicles voltage thus "DIMMING OF THE LIGHTS " will happen

in my case the blower motor slows down when the rad/condensor fans switch to hi speed

at engine rpm above, lets say 1200 rpm the alt should have no trouble handling the load if the alt and the battery are in good condition (alt output is usually tested a 1500 min engine rpm)

here is the distrubing part of my test

A/C on, blower on hi. headlights and fog lights on, radio on brake lights on

trans in gear, idle rpm appx 750 to 800 (this condition simulates being stuck in a traffic jam)

i left the vehicle in this operation for 10 min and the vehicle system voltage dropped to 11.95 volts and was steadly dropping THIS IS NOT GOOD, this is below nominal batt voltage of 12.6

in this condtion how long would it take for my sorento to start to have electric system malfunctions and eventually die, who knows, 1 hour maybe more, maybe less

after i completed this short test my charging sys voltage was 14.10 which showed a signifigent amount of power was remover the battery

and took appx 20 min to bring the voltage back up to 14.35 (befor test voltage)

i think we have all seen dead vehicles on the shoulder or being pushed to the shoulder in traffic jams. this is one of the reasons !

this is not just a KIA or other inexpensive vehicle problem. expensive vehicles suffer from the same problem

BUT if you have a problem with your alt or battery to begin with you have two strike against you to already

so in traffic jams use common sense and turn off non-needed accessories

also, not all vehicles have the same alt output at low rpm it depends on the rpm and design of the charging system

as far as "factory spects" go, i would not trust the mechanics at the dealer i purchased my sorento from to beable to read the spects and know what they mean and even test system properly (not to offend and good mechanics reading this post...there are good mechanics out there too)

also on "factory spects" these are drawn up by engineers for the most part by theory and sometimes don't work very well in real world enviorments

over the years i have disussed may issues with engineers and have found some good ones and bad ones, some will listen, some think they know it all!


note# one size does not fit all, results not typical, blah, blah, blah

my 2 cents
 

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2009 KIA Sedona LX, 2006 Hyundai Sonata 2.4 GL
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145 Posts
Discussion Starter #6
I tried something with my Sorento tonight and not too sure if I stumbled upon something. I pulled both of the fan relays and turned to A/C on. Well the lights didn;t dim all that much. The truck was at idle and at idle I would expect the lights to dim a bit. I would say it was a 100% improvement.

Now the thing I am curious is do the fans always default to high when the A/C kicks in? And are there more than 2 relays that control the fans? The 2 I pulled are at the back of the panel. One was grey and the other was blue.

Are they supposed to go to low first and then to high if they are required to cool the engine? And if they are supposed to only come on low then would I be right to assume there is another relay malfunctioning?

I really don't like the way it was left. I mena I stressed to the tech it was not doing this 3 weeks ago. I told him it was new and I know there is something wrong. He reply was well I don;'t see this leaving you stranded. And while I agree I responded with a resounding yet!!!

The tech there is new and not the guy I was used to. If the "old" tech was there he would take me serious because I didn't waste his time with things that I could fix myself. While I realise there is a warranty I truly believe anything that is small such as adjustments can be done by me and save him the hassle. But maybe in time he will learn that of me and take my request seriously.
 

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2003 Kia Sorento
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606 Posts
The A/C fan automatically comes on whenever the A/C compressor is switched on. This has to happen if you want your A/C to work properly because this is how the heat from the inside of the vehicle is removed from the refrigerant. You probably wouldn't notice a temp difference if you were at highway speeds, but you would at idle or city speeds. I believe the A/C fan only has one speed, where the engine fan is multi-speed, so changing it is not an option.

It's still an odd problem, but it's tough to say what is causing it without looking at it.
 
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