Automotive Air Conditioning Information Forum

2007 Saab 97x 5.3, front air only.

Changed compressor a month ago, with accumulator orphice tube and fresh seals.

Lasted a week and orphice tube plugged with junk.

Today put on a new compressor, condensor, orphice tube, seals, new oil and vacuumed for an hour. All lines flushed.

Charged the system with 2 12oz cans of 134a, bleeding my hose before opening cake to low side.

It's 95 degrees and my pressures at 1500 rpm with engine van screaming are 35 low, 275 high.

Seems fine!

No condensation, and air out of the vents is 60 degrees.

Kicked rpm up to 2k and no change.

I thought maybe I overcharged it, bled a little out and it kicks out on low pressure at about 25 psi.

Took it for a drive and temps get down to 55.

I need help.

Are you using the new components to remove the debris?

Beckett.roy wrote: ↑Sat Aug 03, 2024 3:55 pm Charged the system with 2 12oz cans of 134a, bleeding my hose before opening cake to low side.

The A/C specifications that I have for your SUV, including all model years from 2005 to 2009, are as follows: 30 ounces net weight of R-134a, and 8.0 fluid ounces of PAG-46.

If the above specs are correct, then you undercharged it by about 6 ounces using only two 12-ounce cans, which might or might not contain a full 12 ounces net weight each. Best Practices say to always charge by weight using a refrigerant scale.

How much oil in total did you add?

Do you have an under-hood decal that shows the specs? If so, are they the same or different than those above?

Beckett.roy wrote: ↑Sat Aug 03, 2024 3:55 pm It's 95 degrees and my pressures at 1500 rpm with engine van screaming are 35 low, 275 high.
Seems fine!
No condensation, and air out of the vents is 60 degrees.
Kicked rpm up to 2k and no change.
I thought maybe I overcharged it, bled a little out and it kicks out on low pressure at about 25 psi.
Took it for a drive and temps get down to 55.

The pressures on both the low side and high side are higher than normally expected at that ambient.

No condensation indicates the evaporator isn't cooling much, if at all, as evidenced by the 60°F and 55°F vent temperatures.

I think you undercharged it based on the specs mentioned above.

It shows 18.6 ounces under the hood for no rear ac, this does not have rear ac.

I added 8 measures ounces of oil after flushing lines, replacing condensor and accumulator. I put 4 ounces in the compressor and 2 each in the condensor and accumulator.

If I'm low, wouldn't adding refrigerant drive the high side further up in hot temps?

Drove it to work today, in the 75 degree morning it is cold cold.

In the 95 degree afternoon it would cool under 1500 rpm, but highway speed it would kick in and out. Cool then warm and then cool then warm.

We need a better handle on what the required oil charge is supposed to be. Your sticker has a number for the 134 that is less than what was researched by John. Does it say what the oil charge should be? If not I think we need to find out. You may have an overcharge of oil. It would seem you added the 8 oz of oil before John’s comment. Where did you get that number from?
The under hood sticker always prevails

Sticker says 1.875 pounds r134a and pag oil.

I found the oil amount after extensive searching online.

I was wrong about charge amount since I put in 1.5 pounds and 8 ounces oil.

Beckett.roy wrote: ↑Mon Aug 05, 2024 4:09 pm Sticker says 1.875 pounds r134a and pag oil.
I found the oil amount after extensive searching online.
I was wrong about charge amount since I put in 1.5 pounds and 8 ounces oil.

The specifications on the under-hood sticker match the specs I posted the other day (if indeed the sticker also says 8.0 fluid ounces of PAG-46). Presuming it does, that's good. We can then consider the specs for your car verified.

The first time, you did undercharge it by about 6 ounces, which will definitely affect system operation. Not only that, but a 20-percent undercharge will circulate less oil to the compressor, which will ruin it internally sooner or later.

The best way to proceed from here is, first of all, NOT to run the system with an undercharge. Next, recover the refrigerant, evacuate the system for at least one hour, verify that the vacuum holds, then re-charge it by weight using an accurate refrigerant scale. Alternatively, bring it to a professional MVAC shop and they will handle everything for you.

Im at the point of taking it to get charged, it's too damn hot to have the ac off.

Would undercharge have the high side high? It kicks out on high pressure during the hottest, 100 degrees, afternoon.

Beckett.roy wrote: ↑Mon Aug 05, 2024 6:42 pm Im at the point of taking it to get charged, it's too damn hot to have the ac off.

Sure...I don't blame you.

Beckett.roy wrote: ↑Mon Aug 05, 2024 6:42 pm Would undercharge have the high side high? It kicks out on high pressure during the hottest, 100 degrees, afternoon.

Typically, an undercharge wouldn't affect the high side in that way. The high-side pressure going too high and the compressor disengaging is indicative of either an overcharge or a condensing problem—that is, a condenser that's partially clogged internally, bent fins, debris blocking airflow, wide gaps between the condenser and radiator, missing shrouds, fan issue, and so on. At this point, we can rule out an overcharge, as discussed previously.

Since it's mid-summer now, it might be best to let a professional shop take a look at it, perform any needed repairs, and recharge the system precisely to the manufacturer's specs. That would be the fastest way to cool air.

Totally agree, need pro shop at this point. Try to find a MACS certified shop, they are better trained.