Auto Air Conditioning & Heater Repair: auto airconditioning not cool, electronic leak detector, jeep grand cherokee

Question
I have a 1996 Jeep Grand Cherokee with the straight 6 motor. The A/C no longer cools at all. Prior to my buying the Jeep, the dealer I bought it from said that he replaced the A/C evaporator. The A/C worked fine for the few warm months after we bought it, but this spring it doesn't cool at all. The compressor does engauge when the A/C is turned on. I bought a gauge and checked the low side pressure which reads about 80psi. (I don't have a gauge for the high side).
There are no obvious signs of leaks. What are the possible causes of the system not cooling?

Thanks much in advance

Answer
Most likely there is a SLIGHT leak in the A/C system and your losing freon. If your ONLY reading 80 lbs of pressure on the LOW side with the compressor OFF this indicates that the freon is LOW.

You will need to have to use an electronic leak detector in order to find this SLIGHT leak.

They do make a colored dye that you can put in the system of which will show a dye colored stain where the freon is leaking out of but if the leak is small the dye may not work.

Once to locate the leak you have to empty the system of all freon, Fix the leak, Use a VACUUM PUMP to evacuate all the air from the system and recharge it with the EXACT amount of freon and any refrigerant oil that was lost.

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