How to Find A/C Leak

[ashle232]

Hey everyone, i am looking for a method to find an A/C system leak, but it's really quite difficult for me, share some tips and ideas.

[Bitsyncmaster]

UV dye works very good but you need to inject it into the system. Soapy water also works but takes a little more time and you need to look closely.

[dn010]

UV dye and a UV light make it the easiest and if you have a leak you'll have plenty of room to put it in the system. I've detected bad hoses with the dye without even using a light! If you think you have a leak you should check all fittings and connections to make sure they're tight, also make sure the bolt holding the hoses to the compressor is tight.

[NckT]

It depends what refrigerant is used in the system ie R12 or R134a, but you could use a dedicated (HCFC) refrigerant detector with the long reach hose, such as:

https://m.harborfreight.com/electron...not%20provided

Recovery of the refrigerant and pressure testing with oxygen free nitrogen would be advisable in addition to the UV dye oil injection and circulation to visually highlight leaks using an ultra violet torch, as well a looking at the hoses for oil traces.

Chances are it'll be leaking from the condenser at the front (that's susceptible to damage), the shaft seal of the compressor or the O rings at the pipes to compressor.

Good luck

[David T]

Leak detector solution sprayed onto the suspected parts is the easiest test. It is basically soapy water and any leaks create bubbles. There are dyes you can inject into the system too. Some are require a UV light to see them and some don't. A third method is to use an electronic leak detector but they are not very effective if there is a lot of air movement. If the hoses aren't leaking because they are old, then it is most often the joints that leak and most often the ones on the high side where the pressures and temperatures are the highest. Another big source of leaks are the valve cores in the service valves. They should always be replaced whenever the system is serviced.

[cdrusn]

You are likely to hear the leak before you see it. Do not start the car. Hook up a can of freon to the suction/low side of the system and without turning on the car, inch along the hose fittings at the accumulator, condenser and compressor and listen for a hissing sound. While there look for the green dye you injected. David T. is right, it's most often the schraeder valve at the compressor. If it's in the hose you will hear it along the frame. Mine had a burn hole where it was touching the exhaust after it exited the rear of the compressor. Easy find, difficult repair. With just new hoses, has worked for several years without any leakage.

[David T]

For a visual examination you look for oily spots. When the refrigerant leaks out it takes some of the oil along with it. The oil gets all over and attracts and holds dirt so it is easy to see unless it is a very small leak. Some of the more common areas to inspect:
The entire high pressure hose (the one in the frame on the left side)
The spot where the high pressure hose passes by the steering u-joints
The "O" ring seals on the compressor and the condenser coil.
If the system is "dead" ie, no pressure at all, you can pressurize it with compressed air and look for leaks. If it is flat you will be de-contaminating it anyway so more air won't hurt anything. Again, if it is flat, you should replace all 3 hoses and the dryer and shrader valves and oil. If it hasn't been run in a long time also replace the belt and the idler pulleys. Make sure the mode switch isn't hissing and all of the actuators move appropriately. If it hasn't been run in a really long time, pull the cabin motor and clean out the evaporator box. Clean the condensate drain. As for the service valves (shrader valves) I throw away the plastic caps. They are only meant to keep dirt out, not seal a leaky valve. Get brass caps with tiny "O" rings inside. Do not overtighten them.