Soundcivic: When it works sometimes but not others it's not a low charge. Think about it, once the refrigerant is gone it's gone, and it's not ever going to work again until somebody puts more in.

The exact control configuration depends on your model year, but for most I think if neither the compressor or condenser fan comes on, it's a problem with the controls inside the car, possibly even as simple as the A/C button itself.

If the fan does run but not the compressor, and there is sufficient refrigerant pressure, probably the clutch on the compressor is flakey. This is the most common cause of working sometimes but not others. You can take the clutch plate off and reduce the clutch gap and get reliable operation.

 

you havent charged many AC systems have ya

when the pressure is low the pressure switch will tell the computer and kick the compressor out which will be why its COLD then HOT and you hear it kicking ON and OFF... you refil it with the coolant which of course raises the presure and it will keep it ON like it should operate.
ive done it to my truck SEVERAL TIMES... and my new truck just last week! and my other older vehicles i had with ac.....

 

On a Civic, and nearly all cars of imported design, the pressure cutout is set to 50 psi and it's on the high pressure side. Once the compressor starts even with very low refrigerant it will keep running. Howeverby the timethe starting pressure has gone down to 50 psi,that is long after all cooling effectivenesshas beenlost. Soin other words if you have a slow leak, it will run for a long time with a low charge before the switch is a factor at all. The compressor will start and run constantly but the air from the vents will only be slightly cool at best.

So I stand by my statement that if you can press the button and get good cold air from the vents once, that means the charge is sufficient.When it only works intermittently, but it works good when it does,there is some other problem.

Your experience with American vehicles has been different. That is because most of them have a majorly different system called the Cycling Compressor-Orifice Tube system. On those the low pressure switch is on the low side and it is intended to switch off during normal operation. When the charge is even slightly low it will start to cycle on and off every few seconds.

 

I have a 94 ex, and yea it gets cold when the fan is running. I had it on for about 4 mins and I wss happy so thught it was fixed, turned the car off and tried it again but no luck. Im ganna try that cluch gap and see what it does. Thanks