Auto AC stats and questions

[Redrig]

Hello All ,

Just this weekend I added a mostly new AC system to my 91 Ford Bronco.
I read as many threads as I could and found alot of good info on the webs , just wanted to have some of you AC pros maybe look over my numbers and give me your thoughts.

by the way , new denso comp , all new hoses and drier , new red orifice tube , flushed condenssor and evap multiple times with proper flush. Vacuumed down to 30hg for an hour , then waited another hour and it stayed at 30hg so no leaks.

Right now , I have about 2.5 cans of 134 in the system (and 8oz oil) charging went like I planned but before I go taking back the gauges I wanted some opinions.

ambient temp 95 outside
low side pressure 42
high side pressure 255 ish

those numbers are at idle and if I give it some gas the high side will creep up to about 280 and that is with my mechanical fan and also a box fan set up in driveway to simulate driving.

engine off and the numbers settle to around 115 each side.

I think the low pressure side is good, it pretty much remains rock steady but is the high side too high ?

its working , but my vent temps could be better IMO , the lowest I have seen is 44F. The pipe where the orifice tube is located is sweating like crazy if that means anything and its nice and cold to the touch.

Question 1 - any thoughts for improvements from the above info?

Question 2 - When I flushed the Evap and Condenser I used an AC flush made for these systems, it had kind of a minty smell. As I mentioned, I flushed blew everything out with compressed air multiple times. Then I vacuumed it down for an hour with the vacuum machine running (30hg) Then I closed the ports to ensure I had no leaks , it stayed right at 30hg for another hour verifying no leaks.

This is where I am concerned, as I mentioned about the smell of the flush , today when I was charging the system in between bottles some of the R134 escaped (just for a second ) and I could smell a little bit of that minty smell in it.

So this is more of a physics question on the vacuum process, I was under the impression that when you take it down to 30hg , it boils off everything in there as a vapor and removes everything , all moisture , air , etc . So why I am I smelling that AC flush in the refrigerent when it was at 30hg for over 2 hours ? shouldnt that all be completely gone ?

Sorry for the book , but I wanted to make sure peeps have all the important info. Thanks in advance

 

[dwco5051]

You say you were pulling 30"hg. How was that measured? When evacuating a system you need be talking about miccrons. Takes a good (read expensive) electronic gauge and pump be able reach 50 microns. If you can pump down to 150 you probably got most everything out of the system.

 

[Redrig]

You say you were pulling 30"hg. How was that measured? When evacuating a system you need be talking about miccrons. Takes a good (read expensive) electronic gauge and pump be able reach 50 microns. If you can pump down to 150 you probably got most everything out of the system.

Hi , thanks for the response . I used those ac manifold gauges with the 2 dials for low and high pressure. The low pressure side has a gauge with vacuum on it . It pegs out at 30 and that's where the pump and system maxed out at.

And the vacuum pump was just a rental from O'Reilly.

But yeah , my fear is that I didn't get all of the flush out since the current refrigerant has a bit of that smell in it.

 

[Mcfltfyter]

The vacuum only removes moisture, and can't remove solids. I would think that a mint smell would not be removed.

As long as oil out equals oil in, and refrigerant is added by weight, you should be good. Do not waste your time adding refrigerant by gauge readings, just buy a cheap scale. Overcharged runs hotter than undercharged, so don't add too much thinking it will run cooler.

 

[Redrig]

The vacuum only removes moisture, and can't remove solids. I would think that a mint smell would not be removed.

As long as oil out equals oil in, and refrigerant is added by weight, you should be good. Do not waste your time adding refrigerant by gauge readings, just buy a cheap scale. Overcharged runs hotter than undercharged, so don't add too much thinking it will run cooler.

So would the vacuum remove all liquids that were in the system ? getting rid of all of the flush ?

yeah , I didnt have a scale but I have read about adding the cans using that method . They say to charge at about 80-85% of what the normal R12 charge would be.

 

[Mcfltfyter]

I have no idea what is in the flush you used, but the vacuum should remove anything harmful if a good vacuum is maintained long enough. If it were mine, I'd run that rental pump for a long time, like 12 hours plus. It can't hurt anything, and with less than optimum vacuum it can take a while to remove the moisture. If your system was only open for a few hours and it wasn't very humid out, you are probably fine. It's hard to guess about moisture, but I wouldn't worry about the flush because it won't corrode your system.

Being an r12 conversion, 134a will never perform that great, it just isn't that efficient. I would use duracool for optimum performance, as it is slightly more efficient than r12.

 

[Redrig]

well , I have some good news . I feel like a bit of an idiot though .

The thermometer I was using for these readings is about 7-8 degrees off (10-12$ vent one from oreillys) I used the icewater test trick the other night to test its accuracy and yeah , not too accurate at all. So I got another one that was accurate and I am actually getting 35 degrees when moving and creeps up to about 45ish at a stoplight. That was in about 90 degree weather yesterday, 20 minute or so drive. Thats with 2 tested good thermometers.

That works for me and I will call the process a success. I have a new fan clutch on the way to see if that helps temps and pressures when I am stopped

So the moral of this story is , before you go stressing about results and readings , make sure the damn tool you are using for those readings is accurate.

So thanks everyone for the tips in troubleshooting and help.