You guys have this covered and with current data for the model, but i remember that for my old '98 the manual specifically says to check the center outlet temperature. If within spec, leave pressures alone, even if they seem low!
Pretty much true. What I would like to see in this thread to help me understand, in the following order are:
1. What the ambient temperature was.
2. What the temperature at the center A/C outlet was.
3. What RPM the pressures were measured at.
If you didn't find a repair the leak, then using the vacuum pump didn't help. In fact, it probably just pulled air into the system. It is also pretty obvious from the previous posts that the system is overcharged. You need to recover the R134a, replace all the O-rings (easy job) and replace your accumulator (it contains the filter/drier and is cheap) and then pressure test, leak check, evacuate and then weigh in the correct amount of refrigerant.
A leak would likely only pull air in through the low side, not the high side, and only during fill. Gordon told us that the situation was "from the passage of time and normal leakage. " It's a 2001 truck and the A/C performance fell off last year. Nine years is pretty good with no recharges.
Best way to check for leaks is to pull it into vacuum as high as you can get, then seal it up and see if it holds the vacuum. If it will hold for 30 minutes without dropping, then you are pretty well sealed up.
-snip-
30 minutes to hold vacuum is a good test. When I pulled out the dashboard some years ago for the rotten heater core, I rebuilt the A/C system at the same time. I got it to hold vacuum overnight, because I didn't want to do that nasty job again soon.
Some comments.
Having a dashboard temperature that's "25 degrees below ambient" is a poor benchmark. I live in Metro Phoenix, and when I am in traffic and it's 115F outside, that drop would bring the vent temperature to a "mere" 90 degrees. Obviously that is not going to be acceptable. When the A/C in my truck is in proper order, I can get 42 degrees at the center vent, third click, on recirculate when it's 115 F outside. Now if the ambient temperature was, say, 80 degrees, and the center vent temperature was 25 degrees lower, that would put it at 55 degrees. It would feel good, but still not be correct. At an ambient outdoor 80 degrees, the A/C in our Dodges should be capable of making it uncomfortably cold inside the cab.
I think that something is still wrong here. I am going to go out on a limb and make some long distance suggestions. And I'll quote from the troubleshooting chart that Bob 4x4 posted because that is the way to go at the problem. (And I had a similar issue, once upon a time.
)
I think that this is the key area that you need to focus in on:
LOW SIDE PRESSURE IS TOO LOW, AND HIGH SIDE PRESSURE IS TOO HIGH. 1. Restricted refrigerant flow through the refrigerant lines. 1. (Refer to Plumbing/Caution - Refrigerant Hoses/Lines/Tubes Precautions) in this group. Inspect the refrigerant lines for kinks, tight bends or improper routing. Correct the routing or replace the refrigerant line, if required.
2. Restricted refrigerant flow through the a/c orifice tube. 2. (Refer to Plumbing/A/C Orifice Tube/Diagnosis and Testing) in this group. Replace the liquid line, if required.
3. Restricted refrigerant flow through the a/c condenser. 3. (Refer to Plumbing/A/C Condenser/ Removal/Installation) in this group. Replace the restricted a/c condenser, if required.
I think that the screen on your truck's A/C orifice tube is clogged up. The tube is a $12 to $25 part, depending on where you get it. You should also replace the accumulator at the same time, as scotmartin has suggested. (The accumulator also serves as a moisture filter, and is probably fully saturated by now, anyway. ) And while you are at it, you should replace as many of the green O-Rings as you can reasonably get to. You will save yourself a lot of time and effort if you buy a tiny bottle of O-Ring installation goo, which acts like honey and makes them go on 300% easier than using regular PAG oil.
Also, bear in mind that R-134 systems seem to be a lot more finicky about the weight of refrigerant in the system than the of R-12 systems did. In the old days, an extra half-pound of R-12 made no difference. Now, even an extra ounce of R-134 will actually reduce the cooling capability of your system. All of our trucks should have identical A/C system volumes, but in reality they do not. I have found that mine works best with
exactly two ounces
less than what the factory sticker calls for. I have determined this by using the gauges, the center vent temperature and the charge scale.
There's a mail-order A/C outfit based in Phoenix that also has an advice and discussion forum. They can probably help, and their parts prices are pretty good.
AMA Automotive Air Conditioning Parts & Equipment - Compressors Condensers Accumulators Expansion Va
It's where I buy my parts, because they are local (it gets hot here) and because they have never steered me wrong. And they can fabricate anything!
A word of warning, though: Always use a Mopar evaporator if you have to do the dash removal. This really matters. All other parts are negotiable.
Disclaimer: I am not an A/C tech, nor have I ever played one on TV.
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