A/C leak

[MORRIE]

My A/C no longer blows cold air. Apparently It has a leak in the system. Compressor still works but the system needs R-134A Freon which I can purchase a can at auto parts. . There are 2 ways to check for leaks....dye & a sniffer. Which one would you advise me to use? I saw this on ebay. https://www.ebay.com/itm/Portable-Ha...0AAOSwIw1b0SsG and this also https://www.ebay.com/itm/Interdynami...490a%7Ciid%3A1

[milamookie]

Rent some manifold gages from Autozone. Buy some dye and inject into the system using the gages. Use a UV flashlight to search for the leak.


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[magnetchief]

The leak is more than likely inside of the evaporator where the temp sensing probe sits.

It’s fitted from the drivers side.
Inject the Freon with due.
Run system for a few days.
Remove the cover, pull out the probe and shine your black light inside the hole.
Mine and the other I sorted lit up like a nuclear reactor.

Needed an Evan swap. Not too difficult. Also replaced the drier and control valve.


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[Mr Bingley]

Hi Morrie, if the compressor still works, it means there is enough R134a in the system to at least overcome the low pressure cut-off switch. Have you charged the air before in this car? AC system can leak down very slowly over time (20 years). Yours may not be a catastrophic leak, but rather a very slow one that will hold a charge for a season or so. If so, you could charge it with a dye containing can of R134a and kill two birds with one stone. The big challenge is not to overcharge the system, which is easy to do if you are not familiar with automotive AC systems. But, if it's not blowing cold, and the temperature knob and AC switch are working, you could add 12 oz or so and see. If you have never added freon to an AC system before, you should consider taking it to a shop and having them take a look at the system and add it--over charging the system can be an expensive mistake. Have you done this before?

[steveo539]

In addition to what Mr Bingley mentioned, you can also introduce too much oil into an AC system. That may reduce cooling performance, even with the correct refrigerant charge. Many of the store bought cans of refrigerant also contain oil. If you have NOT had a catastrophic leak (blown hose, broken fitting, etc) that discharged a large amount of refrigerant quickly, you may have not lost much or any oil. As an aside to that, you can sometimes locate a leak by the trace amounts of oil that leak out with the refrigerant. Check all the hose connections and look for oily spots. That may indicate a leak. And if you do decide to crack the system open and replace components, change the fitting seals/O-rings of any fittings you disconnect. AC systems work best with the RIGHT amount of refrigerant, not too little and not too much.

[Vinci]

You may not need dye or a sniffer to find the leak. In a system like this, a leak will push out oil in addition to refrigerant, so look for an oily spot where there shouldn't be oil. Unfortunately, a very common spot for this is the evaporator, which is a pain in the ass.

If you're going to service it yourself, you'll need some specialized tools. FWIW, you're probably still ahead to buy all the tools/parts/etc versus paying someone to do it for you. It's not a fun job, though. In fact, it's the first job on my Z that I swore I'd sell the car before I did again...