AC Performance Update

[gijoecam]

FWIW, I noticed a problem on the freeway the other day....

First of all, I've noticed that the AC just isn't up to snuff lately. It's been working OK at best, but not like I remember it working when it was new. Then, the other day, 90+ degrees ambient, and cruising down the freeway, I noticed that the air coming out of the center vents would get cooler for about 10 seconds, then slowly get warmer over the next 15-20, then a blast of cold for a few seconds, then slowly warmer. It did this with the front and rear fans on high, so I figured something was up. It was set to MAX, and was running continuously, so I figured it was a charge issue. Soooo.....

Today I swiped our refrigeration thermometer from work on the way out the door. I stuck it in the vent, and sure enough, blowing a mild 64 degrees. So, off to the parts store for a can or two of refrigerant. I checked the low side pressure last summer and it was right up at 40 PSI. However, when I checked it in the parking lot of the auto parts store, it was down to 25. High side pressure was only around 200 psi.

So, in goes the first can of refrigerant with some leak-preventer mixed in for good measure. It took the whole can over the course of 15 minutes of idling. At that point, the register temps were down to 56, low side was up around 30, and hgh side was steady at 225 with the engine idling. The chart on the back of the package said that it should be around 250 on the high side, and 35-40 on the low side. So, I grab another can of just freon, and in it goes. It took about 75% of that can, periodically checking low-side pressure as I went, as the high side never really moved above 225, but the low side came up to about 38. At that point, however, the air temps were down to 45, so I stopped there.

Then, I shut the hood and headed home. All I can say is WOW!!!! As soon as I started moving and got some air flow over the condenser, the temps dropped into the 40s. Then, once I got cruising above 45 mph, temps dropped as low as 38!!!! I was absolutely amazed!!! That was on MAX AC, both fans on high, and the windows down to keep the system working hard! I was completely amazed!

Now, I just need to watch the low temp to make sure I'm not icing up the evaporator. Of course, after the fact, I checked the manual and discovered that the engine should have been up at 1500 RPMs when charging it.... guess that would have helped! I noticed that when I revved it slightly, the pressure peaked at about 250 on the high side and 40 on the low side, right at the upper end of the recommended ranges, so I think everything's OK.

All I can say is WOW!!!! Amazing how well it works now!!

-Joe

 

[Oversquare]

What kind of 'freon' did you use? What brand? How much did you pay? Where can we find it?

Thanks!

-B

 

[theven7]

Did the auto parts store let you use their gauge set? I'd like to check my low and high side both, but I don't want to shell out $80 for the guages/hoses.

 

[gijoecam]

The local Auto Zone and Murrays sell a recharge kit made by Intermatic that comes with a hose that connects to the low side port on one end, and a threaded fitting that you can connect to a can tap or the supplied low side gauge on the other end. I had that unit left over from when I converted my Ranger over a few years back.

All I bought this time around was a high-side gauge for $22, and two cans of R-134a (whatever brand was $9.99/can). Then, I was able to check the pressures, remove the low side hose and gauge, install the can-tap, recharge it, checking periodically on the pressures. It wasn't anywhere near as convenient as using the $80 set of manifold gauges, but worked fine.

-Joe