leaking freon - nitrogen ? - DIY Chatroom

wetbar · 06-23-2009, 01:08 PM

Hey I got a unit that I think is leaking freon. I thought i put 5.5 pounds in it last week. the tenant called 3 days later and said it was freezing up. I checked the filter, coils and everything inside and cleaned inside coils. when I put my guages on the low side it did appear to be low on freon. I am still not sure if I am reading the guages correctly. So I recovered all the freon. YUP 5.5 pounds! not one ounce short. But when I pulled a vacuum it would not hold. It would hold for 10 min or so and then drop a little. So to make a long story short I am thinking about using nitrogen, but I dont have a clue how to do this.

Any help ?

sktn77a · 06-23-2009, 01:44 PM

Call an HVAC service tech to help you out.

wetbar · 06-23-2009, 02:32 PM

ok any other suggestions

hvaclover · 06-23-2009, 02:32 PM

what do you propose to do with the nitrogen pressure wise? Need to know so I can tell you which path of repair to take.

wetbar · 06-24-2009, 11:51 AM

Well I was going to start with a 100 and hope I could hear something. If not I will give it another 50 or so, or just see if it is holding. I have other stuff I could do while I wait an hour or so to see if it holds. If I do hear something, just hope I can get to it before I use 20 lbs of N1.

dac122 · 06-24-2009, 11:56 AM

Not sure you're going to hear a small leak. One option is to charge to 200-300 psi and go around with soap bubbles to find the leak. That will only work on fittings, but not the coil. The other is to add a 1/2 pound of charge, add the N1 to 200-300 psi and then use an electronic leak detector. If this is a small leak you may need to be pretty close with a detector. It seems leak detection is part science, art and luck.

wetbar · 06-24-2009, 12:04 PM

I have tried the soap and the leak detector with no luck. I was told (and hoping) I would be able to hear a leak.

hvaclover · 06-24-2009, 01:17 PM

Quote:

Originally Posted by dac122

Not sure you're going to hear a small leak. One option is to charge to 200-300 psi and go around with soap bubbles to find the leak. That will only work on fittings, but not the coil. The other is to add a 1/2 pound of charge, add the N1 to 200-300 psi and then use an electronic leak detector. If this is a small leak you may need to be pretty close with a detector. It seems leak detection is part science, art and luck.

300psig??

Thats a lot higher than some evap press burst test pressures.

veesubotee · 06-25-2009, 10:11 AM

Quote:

Originally Posted by wetbar

Well I was going to start with a 100 and hope I could hear something. If not I will give it another 50 or so, or just see if it is holding. I have other stuff I could do while I wait an hour or so to see if it holds. If I do hear something, just hope I can get to it before I use 20 lbs of N1.

You don't need a constant head (tank valve open). Pressurize to whatever pressure and close off the tank.

A leak anywhere will show on your gauges.

BTW, it's N2

wetbar · 07-01-2009, 02:42 AM

WOW! ok I went to 325 with out hearing anything. The pressure will hold for about an hour, and was holding when I left. I went around with soap with no luck. I was thinking I would go back in the morning to see if it was still holding. MY question is does freon leak faster then N2?