2008 Nissan Sentra AC
Asked by GuruWR1JZ May 21, 2018 at 01:50 PM about the 2009 Nissan Sentra 2.0
Question type: Maintenance & Repair
My AC does not cool when first start the engine;, I can see the compressor running but and the high pressure line not getting hot; after a few minutes of turning on and off the ac control the air starts coming real cool. what could be the problem?
3 Answers
The compressor is running, but is the clutch engaged? If you have to turn the a/c switch on and off, the problem may be at the control switch or the clutch relay.
KevinMooreHVAC answered 6 years ago
Yeah check the compressor clutch. If that's not the problem check your pressure readings on the high- side and low-side. Depending on the type of refrigerant and outdoor air temp it will differ but typically most cars made in the last 20yrs will use refrigerant R-134a and operating pressure on max a/c should read between 30-50psi on the low-side, and 150-250psi on the high-side. (The hotter the outdoor temp. The higher your pressure will be. Look up temperature-pressure charts for the refrigerant your system uses and check the operating pressure on your system compared to the pressure on the chart in relation to the ambient air temperature at the time you are taking the readings).
KevinMooreHVAC answered 6 years ago
If your compressor clutch is engaging, then your system could be slightly undercharged which could cause it to finally cool after running for a while because thats when the refrigerant in the system has built up enough pressure to somewhat work.
