Replaced A/C high and low lines, now what?

[Benjamin Mason]

I have a 2000 Chevy Lumina, the A/C doesn’t get cold and I know there’s a leak somewhere. I replaced both the high and low lines where you find the ports. I know the rest works cuz I can pump R134 in and the clutch engages and the air is cold for like a day. I just did the high side line today, and it still won’t hold vacuum. After 10 minutes it had dropped from -30 to -15. I have used UV dye and I can’t find a leak anywhere. I’m stumped. Looking for any advice what to try next before I take it in. Also, bonus question…there is a sensor (or some other electrical component) plugged into the high side line just after the receiver dryer. What does this do? It has a Schrader valve on the line which goes to an electrical sensor of some sort I’m guessing. Complete amateur here, full disclosure. Hope someone sees this and can give me an idea what else I can try. I’m having fun doing it myself, learning along the way, and not breaking my bank along the way. Thanks!

Topic

[college man]

If you have searched all the obvious spots with a black light and see no dye,
I would suspect the evap. If its running out in a day thats a big leak. The connector
on the high side could be a high pressure switch. To confirm the evap is the problem
use some refrigerant as a trace charge and use an electronic sniffer to check. more
in this link.

http://www.ericthecarguy.com/faq/solving-automotive-hvac-problems

[Larry Bible]

Before replacing the evaporator, since you can make it cool with the dye in the system, run it enough so that it is making condensation. Put the car out of the sun and use the black light to look for dye in the condensation water on the shop floor and in the inside of the drain hose. If the evaporator is leaking,you will see uv dye there.

If it is a difficult evaporator to change, as many of them are, go to an auto a/c shop for a leak check before changing the evaporator. They can use a few ounces of R22 and pressurize it with nitrogen, then check with a sniffer. The sniffers pick up R22 really well and the nitrogen puts the portions of the system normally under low pressure, under high pressure, showing up the leak better. Especially good for diagnosing an evaporator.

Hope this helps.

[Benjamin Mason]

Thanks for replying. Looks like it’s time to conceed to my amateurity and take it in to a professional. Thanks again guys!

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