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2011 Kia Optima
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Discussion Starter · #1 ·
Hello,
I searched related issues and so far I have been unable to pinpoint the issue with my A/C system. I'll outline what I have done so far and would appreciate any tips or suggestions. This may not be related to the current issue, but I have always had intermittent issues with the A/C even when the car was new. Sometimes I would turn on the A/C and would get warm air for a few minutes and all of a sudden it would get really cold. I took it to the dealer a couple of times, but they were unable to replicate the issue and I just lived with it. Now I don't get any cold air. This is what I have done so far:
  1. I bought a can of A/C Pro recharge kit and connected it to my low side. I turned on the A/C full blast and the needle was right on the border of low and filled. I added some refrigerant, but it didn't work.
  2. The high side pipe gets hot, but the low side does not cool down.
  3. I checked the evaporator temp sensor and it seemed to be working fine. The resistance I read was around 35C which is close to the ambient temperature.
  4. I have 12 volts going to the compressor's control valve.
  5. I checked the pressure transducer and was reading 61 and 83 psi with the A/C off and on (1.044V and 1.245V)
The compressor seems to be working because the high side is getting hot. Is this a correct assumption? Can the condenser and/or evaporator become clogged?
Thanks,
Ali
 

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Replace the electronic control valve in the back of the compressor. This fixes the problem 99.9% of the time, but there have been a couple of times the valve was replaced and it didn't work/correct the condition, but a new compressor did the trick. Now I wouldn't know if it were actually a faulty valve that was installed, a problem with the installation itself, or actually that the compressor was at fault, but installing a new compressor fixed the problem, but once again, there was a new valve that came with the compressor.
Discharge the system, install the valve, or compressor with new o rings, evacuate, charge 19.3 lbs 134.
 

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Discussion Starter · #3 ·
Thank you. If the valve was faulty, wouldn't it prevent the compressor from compressing? The high side of the compressor gets hot, which happens during the compression phase. Do you happen to know the part number for the valve? I didn't know it was replaceable.
 

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The compressor is a variable displacement compressor, meaning that the compressor is turning ALL the time, even with the AC OFF. The valve controls what is known as the swash plate, and that in turns changes the stroke of the pistons to meet the cooling demand, increase, and visa versa, decrease the stroke when cooling demand is low. When that valve goes, at first start, it takes sometimes 5-10 minutes before the cooling starts, but when operating, it will freeze one out, and at idle, the cooling is diminished. Three, four years ago, our '11 was like that, delayed cooling until one day it stopped completely. Not much info available, but after all the tests, charge, evap temp sensor, fans, voltage, transducer, etc and as it was 95F, no time to order the valve, but as the OEM compressor at 120,000 miles was noisy, went with a used unit, 21,000 miles $60.

From past information, the new valve has fixed the problem, but do know of 2 that the valve didn't work properly and another compressor was installed. Was the new valve faulty, installation inadequate, or was it the compressor internals that were problematic, wouldn't know unless one were to investigate.

Here's some reading:

The system needs to be discharged to replaced that valve, evacuate for a period of time, add 19.3 oz R134A.

Let us know how you make out.

Below is the diagram of the control valve, OEM $143/107, however, aftermarket valves are available from many places, ebay, Amazon etc @ $30+/-.
249000
 

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Discussion Starter · #5 ·
That's awesome information. Thank you very much. I think it may be worthwhile to try the valve.

If the high side is getting hot, the valve must be allowing some displacement in the compressor, right? Wouldn't that cause some cooling? Could this be caused by the expansion valve.

I'm trying to think what else I can swap after the system has been evacuated. I'm thinking the dryer/desiccant along with the valve.
 

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With a compressor replacement or valve replacement, no need to do any other changes, expecially when there wasn't and internal damage, but I'd put gauges on the system to see pressures.
 
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