I got my

"InterDynamics Certified AC Pro Car Air Conditioner Test Thermometer, Reads 0 to 220 Degrees Fahrenheit, Includes Holder and Clip, TH27"

"InterDynamics Certified AC Pro Car Air Conditioner Test Thermometer, Reads 0 to 220 Degrees Fahrenheit, Includes Holder and Clip, TH27"

whew-what-a-mouthful thermometer this morning and took a nonscientific temperature reading of my center A/C vent temperature.

Conditions: 90 degrees outside, bright sun, hot enough interior.
Settings: Regular AC (not max), not auto mode, left hand dial set to 71 Degrees on the console, NOT RECIRC, vents set to floor/face, fan setting 3.

I drove about 10 miles on regular roads, around 40-50 MPH. Pulled in, stopped car. It was a comfortable temperature inside the car.

Temperature at the center dash vent: 44 degrees.

This test isn't very rigorous but it shows that even with the A/C not on MAX and with the climate control mixing the interior to 71 degrees (not the coldest) and not on recirc on a fairly hot day, the vent temperature can be/should go well under 50 degrees, at least on this car. So the A/C is working well. I think on MAX/RECIRC/MAX COLD it would/could get even colder, perhaps in the high 30's but that would be getting close to the evaporator freeze. I've felt the air coming out of the vents be a bit colder but didn't have a thermometer to measure at the time. You can sense the TXV valve working because the vent temperature fluctuates as the climate control system tries to maintain your chosen temp.

 

I have to check mine again when it's 90+ out. I still haven't used it, just roll 2 windows down and enjoy that juicy gas mileage.

 

So I checked it out. I hit 50-60F out of the vents in city driving when its 95-100f out. I checked the pressure, it was a little low so I added some but no change. My can tap and H/P hose end is cheap and broke pretty quickly. I'm going to get the replacement and eventually rebuild the A/C. I notice that when I drive fast it finally drops below 60. Probably that blocked up condenser. I can say the a/c "works" good enough for the battery and really to cool you if you're not too picky but the engine runs a lot more, killing mileage due to inefficiency. Definitely better with recirc than with outside air.

 

So I just learned an important lesson. DO NOT use the common R134a pressure charts to fill your car. I was at 45 and expecting 50/55 on the low side under high heat. After watching the BSG video on overcharging, his low is between 30 and 40 PSI. Closer to the 30 even. I don't know what chart I should be using for low and high side now. What I do know is that by recovering some refrigerant and getting down to 30-34PSI I have a 5 degree drop at the vents while idle. Plus the needle stopped bouncing completely. We need a chart that works and the internet seems to not deliver.

 

That's GREAT (and not so great for obvious reasons) to hear, because my suspicion was that you were overcharged. His video is pretty good and you're right, there are not many good charts about it in the Infinite Elsewhere, which is why I was reluctant to contradict you, since I don't know either. But I'll guarantee there are a lot of people out there driving around with overcharged systems as well. Then they suffer a while longer with mediocre cooling, their compressor maybe fails, and now it's an expen$ive job, and the mechanic says: "See! You always needed a new compressor." Not that I think any reputable mechanics would do that, of course.

Now you know it's cooling better and when you have the time to get that condenser replaced and everything 100% in spec. it will be perfect(er). IIRC he doesn't even use a chart and talks down the "static pressure readings" - he just shows the system when it's operating marginally, when it's overcharged, and when it's operating well with his gauges.

There are people I've read on the interwebs (many of them are probably mechanics) who just think: "Oh, yeah, if it's warm, just pump some more in there!" Wrong. Not more cowbell. Less cowbell.

"The Wrench Turns Hot, the Wrench Turns Cool."

 

I have to take a static pressure reading to see if there is truly enough but that's kinda pointing to my TXV since it takes quite a while for it to equalize. Swapping the trifecta of condenser/txv/drier sounds like it should take it all out in theory. The compressor looks like NBD to change, just how much oil to put in is a mystery. The worst part about this is that I have a 85% A/C system and it's a bit of work to make it closer to 100%.

 

Yeah trying to get that last 15% with all the time involved is a bummer, and nothing great to look forward to to get it, but at least it's working well now and you can watch it, so you have time. I'll try to find more info. on the amount of oil to add, I remember seeing it somewhere. And if/when you do decide to do it you'll have the new receiver/drier in there and not worry about the "bursting bag of dessicant" aneuryism/clogged artery heart failure for a long time to come, which on yours is an even bigger PITA than mine.