crazyd Posted July 22, 2011 Report Share Posted July 22, 2011 (edited) So I replaced the filter/drier unit and a leaking low-side valve core in preparation for the system charge. Last night I went for it. I have a set of the U.S. General A/C gauges from Harbor Freight, a vacuum pump from Autozone, and a probe-type thermometer for checking the air vent temperatures. Here's what it all looks like: I vacuumed down the system as low as it would go (about 29in Hg) and waited about five minutes to see if it held. When it did, I moved forward with the oil can, a medium-vis PAG from Wal-Mart ($5). Watching the pressure on the gauge and checking the can regularly, I gave it as much as it would take then attached the first can of R-134A and started the engine, setting all the interior climate controls to MAX. The standard is 75-90% of R-12 by weight, and the label on my '92 at the right strut tower says 2.25lbs (or 36 ounces). So a 75% R-134a charge would be 27oz. Well, using two cans at 12oz each plus the oil charge can which included an additional 2oz gives a total of 26oz. At a 70 degree ambient temp, with the car idling through the charge for about half an hour and the coolant temp at 230, I got 47F at the vents. Took the car for a spin and once the engine temp came down to normal, the air temp went down to about 40F at the vents. Let the system cool down for a few hours and then I rechecked the static low-side pressure and compared it to this chart: http://www.glacierbay.com/ptchart134a.asp. Everything looked good. Rained here all day today and never got above 60, but tomorrow and Saturday are supposed to be the hot ones, so we'll see how it does then. Edited July 22, 2011 by crazyd Quote Link to comment Share on other sites More sharing options...
bronze93 Posted July 22, 2011 Report Share Posted July 22, 2011 If I am reading the chart right at 69.24 deg outside the pressure should be 70 psi at the low pressure port? Here in Maryland it is about 100 deg outside so I should have a low pressure of125? It is very hot and I'm been troubleshooting the AC for a leak the last couple days. With the temps at 100, the heat index at 110, and my hour daily commute the ac doesn't like to keep up. Quote Link to comment Share on other sites More sharing options...
crazyd Posted July 22, 2011 Author Report Share Posted July 22, 2011 I believe that's only a static low-side pressure, meaning when the system isn't running and both low and high sides are in balance. When running, the low-side pressure should be 23-29psi and the high-side will be much higher. Quote Link to comment Share on other sites More sharing options...
AL Posted July 23, 2011 Report Share Posted July 23, 2011 The low should actually be higher than that... 35-45 range actually... While running with AC full blast that is Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.