A C help

[mytoy]

I changed my 78 vette over to the 134 a a few years back, the problem is I believe I have a leak, does the dye that you can purchase from Auto Zone work ,and how do you install it , will it take it with the system empty,Is there any certain o ring that leaks more than another, Any help would be appreciated Mytoy

 

[tedster]

Refrigerant dyes mix with oil and the oil mixes with the liquid refrigerant. As the refrigerant evaporates, the oil/dye is carried by the vapor as an entrained mist. The oil will migrate to and thru the leaks, carrying the dye with it. To use the dye you need to add it and run the system long enough for it to circulate. But if the leak is significant, you may see oil even without the dye.

You can do a quick visual inspection of the plumbing, connections, fill ports condenser and compressor. If you see oil (dyed or not) at any of these points, that's where your leak is. In particular, check the compressor, between the clutch pulley and housing for signs of oil, indicating a shaft seal leak.

If the shaft seal is OK, the next most likely culprit is the evaporator. You need to do some disassembly to be able to see the evap. Most leaking evaporators have been doing so for quite some time....(hmmmm no cold air...let me add some refrigerant....then repeat next spring...) and there is often an obvious build-up of oil on the core by the leak and in the bottom of the housing.

Hope this helps.

Tedster

 

[wishuwerehere82]

Mytoy,

There are a few differences in materials compatability between the original R12 and R 134A. The o-rings that were in the R12 system will degrade with exposure to R134A. The R 134A O-rings are Blue in color.
The main locations of the O-rings are at the compressor line fittings and at the connections between the Evaporator, Dryer, and Condensor.

The dye to use is a U/V traceable dye that shows up under black light. But putting dye in the R134A is a last resort to finding the leak. You can waste a lot of coolant doing it that way.
When you open the system to put in new O-rings, all of the old oil should be drained out of the system. Once the system is tight, put a vacuum pump with a gauge on the Schrader valve fitting and evacuate the system down as close to 32 inches of mercury as you can get. Close off the vacuum line with a valve and let it sit for at least an hour. Watch the Vacuum gauge to see if you have a leak in the system. If it leaks, then go to the fittings and make sure they are extra tight.

If you still can't find the leak that way, pump the system back down to a high Vacuum, then disconnect the vacuum pump and insert the line that went to the vacuum pump into your bottle of compressor oil with the dye in it and use the Vacuum in the system to suck it into the A/C system. Make sure you don't let any air into the system, it should have a vacuum in it as you introduce R143A back into it.
Hook up the pump line to your 134A can then refill the system with your R134A and run it. Use a black light around the compressor shaft and all of the fittings to spot the leak.
That's the way I do it.