I have an 2009 infiniti qx70 that is having A/C issue when stopped. Car works fine when moving and A/C blows cold. Once I stop at a red light, it cuts off and no cold air. I've checked coolant level, refrigerant, radiator, AC compressor is running and not seized. What else can I check at this point?


Pressure test the system from the high pressure line to the low pressure line. Check the Condenser. Either there is a leak in the system or its clogged.

Does the radiator and condenser fan turn 'On' while the AC is engaged?

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    Yeah, both fans are turning on and AC compressor is engaging. I see no leaks at all. I'll get a pressure tester. How do I look for clogs? – Noah Jun 26 '17 at 16:43
  • Clogging would normally occur at the expansion valve. But then again there is no challenge to have it anywhere in the ac circulation system. – Numair Aidroos Jun 26 '17 at 17:18
  • @Noah This is one way to test it, it's a bit pricey, but the tool is worth a lot of time. youtube.com/watch?v=ajcD90Ll_Ik – Numair Aidroos Jun 29 '17 at 12:21
  • Did it workout for you? – Numair Aidroos Jul 11 '17 at 1:20

Did you or someone recently "top off" the refrigerant? Overheating in the condenser with too much fluid can cause the high pressure limit switch to engage, stopping the compressor. If you get it warm and run it in your driveway, when the AC stops does the compressor also stop? Running on the highway may be enough to cool the condenser completely, reducing high-side pressure.

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    I didn't top off the refrigerant or added any. – Noah Jun 26 '17 at 19:49

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