Last Fall my AC was not pumping out cold air.

Dave, if your system happens to still have a positive pressure within itself, then mix up a soap/water solution and spray this on the fittings etc. Let the solution sit for a few minutes (at least ten). Check for bubbling. They actually make a bubble leak solution that can be purchased, but you can make your own. Also, there are professional leak detectors, but they are costly. Good luck hunting!

A couple of ways.
You can charge it with nitrogen(using gauges), and let it sit and see if it looses pressure. This takes time....and access to nitrogen.

You could also evacuate the system(requires a vacuum pump and gauges), which pulls a steady vacuum on it. Depending on the pump, this will take around an hour...sometimes less. I like pulling them down for at least that long, as it eliminates any/all moisture from the system. Others have differing opinions.  It should hold the vacuum, usually around 25-30" for at least an hour after evacuating.

My first suggestion is to see if the system has a charge in it now. Unless you know for sure it has a leak, then re-charging it is kinda like putting the cart before the horse.... Put some gauges on it, and see what you're starting with. If the system is empty, or very low, then you know you have a leak. If low, then a leak detector would be the best way to find it. If empty, it will need to be charged with something to find the leak. If it has the correct pressures, then your problem is elsewhere. Gotta start with the basics.

Simple Green acts as a good leak detector.

You can get a relatively inexpensive vacuum pump from Harbor Freight is you decide to evacuate the system but I'd first determine if there's a leak like suggested above.

|UPDATED|4/28/2013 9:21:05 AM (AZT)|/UPDATED|