2014 Chev Trax - Need help diagnosing

[KillerPancake]

Hello!

I've got a cooling performance issue on my 2014 Trax. I purchased this car used a few months back, and the issue has been present since then. I am not an automotive AC expert, and with the data I have been able to gather, the problem is not jumping out at me. Hoping that the experience on this forum can help!

What I know about the car:
- About 130K km / 82K miles
- Holds 570g / 1.26lb R134
- Clutch-type compressor

The problem is that at idle, there is basically no cooling. Raising the RPM helps things improve, but not really effective cooling. Going down the highway with ~2600 RPM with lots of air through the condenser, the cooling is pretty good. Seems like possibly a simple low-charge performance issue, but I have re-charged the system (by weight, best I could) and there was absolutely no change at all.

Please also note that the system is currently charged with R12A (note carefully, R12*A*, not R12). R12A is what a DIYer can get here in Canada, R134 is not available off the shelf. What I understand about R12A:
- Fully compatible with R134 systems.
- About 40% less is used by weight when compared to R134.
- Low pressure performance is similar to R134 while the high pressure side runs 5-10% less pressure.
- I'm not sure how the static pressure is supposed to compare.
- Here's a sample product: https://emzone.ca/product/12a-a-c-cool-refrigerant/

Here are my readings and observations:

Ambient: 21.5 deg C / 71 deg F
Static Pressure: ~62 PSI

At idle (~780 RPM)
Low side: 40-48 PSI
High side: 145-200 PSI
Cooling Fan: 2s on, 27s off

At 1800 RPM
Low side: 20-28 PSI
High side: 155-212 PSI
Cooling Fan: 2s on, 10s off

The variation in pressure was tied to the fan cycling - it would creep up to the higher numbers in the range then drop when the cooling fan came on. Also, I did not notice the compressor cycling at all. At idle it was easy enough to tell that it was on constantly, perhaps a bit more difficult to tell at 1800 RPM but I did not notice it cycle off at all.

Hoping that some gurus on the forum could provide some guidance on the possible issue!

[tbirdtbird]

So many things run through my mind when I read this stuff. Kinda hard to tell the difference between Canada and a certain WW2 country.
For testing purposes you are way better off with a higher ambient, like 80° or higher.
You provided a lot of data, but no vent temps. We need vent temps. With a dial thermometer, not an IR gun
Here is what we need:
A full load test:
1500-1800 RPM
AC max cold setting
Max fan setting
Recirc on
doors open
Provide ambient, and hi and low and vent under those conditions.
And we typically pay little attention to static pressures.

Personally, I prefer to have my fan run any time the comp is on, and will rewire any cars that show up here to do that. You yourself can see the difference in your readings. It would seem that the OEMs are having a contest to see which one can make an AC system as unnecessarily complicated as possible.
Your 12A is a mix of propane and isobutane, which is why the can is emblazoned with **CAUTION EXPLOSIVE**
see the data sheet here. These are hydrocarbon refrigerants, and dangerous. If too many people blow themselves up with this stuff, the economy will suffer since not as many will be there to pay taxes. Sorry had to rant.
https://emzone.ca/wp-content/uploads/20 ... 0_g_en.pdf

You did not say how you weighed in the refrigerant. The system only holds a small amount of 12A, so the charge needs to be exact. I would figure out how to make that happen. Some people report they are having good luck with electronic postage scales. I have never done that so cannot comment. One of the consultants here (JohnHere) recently reviewed the consumer critiques for several of them and found the critiques to demonstrate mentionable shortcomings. Of course we use pro refrigerant scales. Pull a hard vacuum with a motor driven vac pump (be very careful of discharging the 12A so no one gets burned or worse), for at least an hr, and charge using a precise method, or have a shop weigh in the correct amount of 134 or 12A.

Is the condenser close (max 1/2") to the rad, with air dams all around to force the air to go thru both structures, and not around?

Good luck and Report back

[DetroitAC]

I think that 40% less rule of thumb charge idea has you all messed up.

What is the temperature coming out of each vent in conditions like t bird described? I'm betting one or two are cold, others warm.

What temperature is the suction line? Warm I'm betting, maybe cool but probably not cold?