Automotive Air Conditioning Information Forum

No, I was not revving the engine up when charging. That's not something I've had do with other vehicles so I didn't think about that.
Run the engine at about 1,800 RPM with the A/C system turned on while charging it. If everything is working as it should, the compressor will engage and draw-in ...

My initial plan was to replace the complete ac system because of the age. I have a brother in law that can get all the parts at a super price. My only problem is the evaporator. That will be a real pita to replace. I would flush it but I don’t know if my compressor is big enough to accomplish that ...

I weighed the cans when I charged it.
Does your scale "zero" and "count up"—that is, weigh only the refrigerant going into the system and not the refrigerant plus the cans themselves? If not, then the system might be undercharged.


Another symptom, I sometimes hear a high pitched sound in the ...

The 80-90 PSI reading on the low side is considerably more pressure than that in the can of refrigerant and is why the system won't accept any more.

Is the compressor running at an engine speed of ~1,800 RPM when you're attempting to charge it?

Are you sure you have an unobstructed path from the ...

With a low side of 48 PSI with R-1234yf, the evaporator is going to be operating around 50°F when it should normalize at ~30 PSI on a 90°F-plus day, corresponding to an evaporator temperature of about 33°F. The 48 PSI/50°F reading obviously isn't cool enough to provide a center vent temperature of ...

Is that a 2017 RAM, and are you sure that it takes R-1234yf? Does the under-hood decal specify that? My reference sources say 23 ounces net weight of R-134a, and 6.0 fluid ounces of PAG-46.

Regardless, let's start off with the correct amount of refrigerant, precisely weighed into a well-held vacuum ...

At 18-22 PSI on the low side, and 23 PSI now, you'd be running the evaporator at about 19-25°F, promoting evaporator freeze-up and blocking airflow, unless you have some kind of mechanism to cycle the compressor.

In this instance, possible causes include the system developed a leak, undercharging ...

Is the evaporator icing-up and blocking airflow after running the system for a while? Evaporator icing could explain the cold-to-warm-to-cold cycling.

At a 30°F vent temperature (too cold) coupled with the low, low-side pressure, the system appears to be undercharged.

Given your truck's mileage—and presuming the compressor assembly is the original—I would replace it anyway. Many compressors don't last beyond 100,000 miles. There are some exceptions.

By replacing the compressor assembly, you will eliminate the clutch-gap question as well because it will come with ...

If it's annual seasonal losses from the compressor shaft seal, you might be able to get away with just a recovery, evacuation, and recharge. I would still replace the accumulator (it has desiccant in it, a moisture absorbing substance), and OT.

Pay particular attention to the condition to the OT ...