Alright guys so I'm having a difficult problem with my a/c system. I'm somewhat of a mechanic so il list down things I've done to try and fix the problem. But long story short my a/c runs great in temps from 30-60 farenheit. Once the temp reaches 70 or higher my a/c stops running after 30 min. Both my compressor and condenser fan turn off and they do not engage till the next morning when I hop in to go to work. Mornings I never had a problem but in the afternoon when the temps are higher it only works for about 30 min. Things I've done to fix the issue are:

  1. Vacuum the a/c system out and fix any system leaks. Refill with correct a/c ounce capacity (around 17-19 ounces)

  2. Replace the binary a/c pressure switch.

  3. Check the a/c fan and condenser fan relays (yes they work)

  4. When the a/c stops working, the low pressure gauge reads over 60 while the high pressure gauge reads only 150.

Your input is appreciated

  • Get a wiring schematic for the AC system and use a test light to find out where the 12v to the compressor is cut off. Please post the specific year you are working on and engine size.
    – Moab
    Jul 10, 2020 at 13:17
  • 95 civic 1.5 liter Jul 10, 2020 at 20:54
  • That AC clutch relay is controlled by the engine control Module, and the ac compressor itself has thermal overload protection, you are going to have to use a multimeter when it stops working to figure this one out.
    – Moab
    Jul 10, 2020 at 21:34
  • If you find it is the thermal protector that is keeping the clutch from engaging, then suspect not enough oil in the system.
    – Moab
    Jul 10, 2020 at 21:43
  • Never knew about the thermal protector! Il try that. Thanks mechanic sensei Jul 13, 2020 at 22:44

1 Answer 1


Looks like you have a high low-side and a low high-side pressure. This can be caused by too much refrigerant flowing into the evaporator, so it doesn't have room to expand (which is how the cooling happens).

Common problems for this are

  1. The thermostatic expansion valve is stuck open or the thermal bulb is not sensing the temperature correctly.
  2. The orifice tube opening is too large, or the O-ring sealing the outside of the orifice tube is not sealing.

These are just basic guesses without knowing more about the vehicle.


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