A/C nitrogen testing in Houston?
 

Hi everyone,

First post, although this forum has truly been a life saver since I bought my 83SC 7 years ago. I’m almost done with the installation of an electrocooler in my car and need to find a place to have it tested and charged. The manual calls for a nitrogen pressure test but I haven’t found any shops in the Houston area willing to do it.

For those in South Texas who have one of these units installed, were you able to find a shop capable of testing for leaks using nitrogen?

Roger

I’d like to hear your thoughts about your new AC once you get it sorted out. I’m interested in one as well.

Dry nitrogen is a great way to test it. I simply bought a set of pressure valves and a small tank of nitrogen for myself. It is not very expensive. Around here the tank is just a swap out for a refill so no worry about the tank going out of date. If you have a modern car around that has nitrogen in the tires, you can get a tire valve chuck and top off the tires. The nitrogen has zero moisture in it.

Go to a local welding supply store, and see what they charge for a regulator set to get the pressure from 2,000 psi to something you can set from 10 psi to 150. They may well rent it for a month to month fee as well.

I am total overkill when it comes to pulling a vacuum on my 911 AC system. The many feet of hose from front to back and the 4 condensers I have is a lot of places for moisture to hide.

I pull a vacuum for a couple of hours, then pressurize the system with nitrogen to 120 PSI, and I let that sit overnight to test for leaks. Leaks will show up a LOT faster at 120 PSI than under a vacuum. If the pressure is still about 120 in the morning, I pull another vacuum for a couple of hours. Then pressurize with nitrogen for an hour. Then I change the oil in my vacuum pump, and pull a four hour vacuum.

That is when it is finally ready to add refrigerant.

Here is a regulator like mine. Pretty cheap.

https://www.amazon.com/Nitrogen-Regulator-Delivery-Pressure-Connection/dp/B07QKB14NM/ref=sr_1_4?dchild=1&keywords=Nitrogen+pressure+reg ulator&qid=1599141379&sr=8-4

All you need is a hose from a AC set. The gauges make it easier. Even if you don't want to charge the system, do all that prep before you take it to a pro.

I ended up calling a couple of Porsche shops. unfortunately the first one didn't do the test despite my asking for it multiple times and them having the manual which says to do this. Another shop checked with their mobile AC guy and he said sure he could do it, and he did. Immediately found the leak that we'd been chasing with vacuum and dye for a month, fixed it in 20 minutes, so definitely do not skip this step.

I looked at doing it myself but was unsure what connectors I would need to connect the nitrogen into the AC system.

Great advice from everyone. If I can’t find a shop that can do it, I’ll look closer into doing it myself. Looks like it’s definitively recommended.

The real difference is a perfect vacuum is less than 15 psi even at sea level. Less than that higher up in altitude. With nitrogen, it bubbles out, and easy to go to 120 psi or more. A little soapy water and bubbles will appear. If it can hold 120 psi with no leaks it will likely be fine.