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I have a 2006 Jetta TDI. The AC light on the button illuminates when pushed, but the air does not get cold. I recently had the system charged (at least they told me they did).

Fault Code P1641 is stored in the system. DTC Memory of AC Controler...

Any ideas? I used a vadas software to access the code via a laptop computer. There is a button to communicate with the AC ECU, but when it attempts to connect, it fails, and is unable to communicate.

Thanks for any advice.
 

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A few possible issues: bad ac compressor (a solenoid inside fails), bad switch, and some people have said that their resistor packs go bad but I don't know if the light would illuminate. Does changing the fan speed make any difference?
 

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I don't hear the compressor turn on when you select ac in the car. Changing fan speed doesn't help. Can the compressor be overhauled? Or just get a new one... Thanks for the help.
 

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There are overhauled automotive AC compressors on the market, but you will need the freon recovery and system evacuation equipment to perform the scope of work without violating the applicable EPA regulations.

Find a reputable local repair facility that specializes in automotive AC systems and have them perform the compressor swap. They often include a short-term warranty on their work, 6-months or so, when they are a reputable facility. I had my AC compressor swapped at a local repair shop when I lived in NH and the compressor clutch came apart, no it actually shot metal components around the engine compartment, about 3-months later. This was no fault of the repair facility, as this was work performed by the compressor overhaul facility, but they still honored the warranty and swapped it out for me.

Some good questions to shake down an automotive AC repair facility is to ask them questions about their system evacuation and leak down tests. They should be pulling the repaired system down into a vacuum of less than 500 microns. If they show you a simple compound bourdon tube gauge and not a digital micron vacuum gauge, they are not equipped with the top end tooling and you won't receive the highest quality work. Also, they should be leak checking your system by establishing a 500 micron or less vacuum, then securing the vacuum pump and letting the system sit for 30-minutes without the system vacuum climbing to above 500 microns. Another bonus, but not a real requirement for a small system like this, is to charge the system with nitrogen to 125% of the normal high side discharge pressure and perform both a static leak down test and a soapy water solution check of all the components that are accessible. The reason that a static pressure test is not essential for an automotive AC system is due to the internal volume of the system, which will show a rapid increase in the micron values when there is a system leak or in some cases a vacuum of less than 500 microns can not be achieved.

All of the shipboard HVAC systems that I have supervised, upwards of 100-ton HVAC systems, and passed the 500-micron evacuation protocol coupled with the 125% static pressure nitrogen check have proved to be very reliable and leak-free. Other techs that have skirted these protocols were back into their HVAC systems with problems in days/weeks following the repairs and were dealing with a loss of charge, non-condensible gas problems (left over nitrogen in the system, both from static pressure tests and normal outside air)...
 

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My problem is that the AC light does not come on when the button is pressed. What are things I can check to determine the issue? The fan works fine.
 
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