AC not very cold at idle, great while driving

[tbirdtbird]

Maybe its just me but I am not certain that 49° qualifies as 'nice and cool'

that would not fly in TX or AZ

[Tim]

Maybe its just me but I am not certain that 49° qualifies as 'nice and cool'

that would not fly in TX or AZ

It does when it's 118 out.

[Jonas]

So, I lost a little oil and refrigerant from those gauges that didn't work. Will I still be able to proceed with the diagnosis, or is there anything I should do now? Will my AC be okay for now? I bought another set of gauges and they didn't work either. Fortunately, I didn't attach them to the lines-one of the knobs was broken. I'd love to get the pressure readings. FWIW, the low side on those gauges told me the static pressure was about 75psi and the low side while running was about 32 at idle in mid 80's weather. Seems low to me, but I don't trust those gauges either. AC is still doing ok. No better or worse.

[Jonas]

I have a low side charge hose, should I add some more refrigerant, or is that a bad idea?

[Jonas]

What speed (RPM) does your engine idle at?, what is it going down the road when things are nice and cool?

With AC on, it idles around 800 in drive and a tad higher in park. I average about 1500-1800 RPM cruising in town. About 2200-2500 on the interstate.

[tbirdtbird]

no need to add oil or refrigerant because of the small amount u lost.

Pressures mean the most at about 1500 RPM. A compressor doesn't do much at idle

If you didn't have bad luck with gauges you wouldn't have any luck at all

[Jonas]

no need to add oil or refrigerant because of the small amount u lost.

Pressures mean the most at about 1500 RPM. A compressor doesn't do much at idle

If you didn't have bad luck with gauges you wouldn't have any luck at all

That's a relief. If compressors don't do much at idle, how to -good- ACs stay cold when stuck in traffic? Could my belt be slipping, but not making noise?

[tbirdtbird]

Your system is not optimally 'tuned' yet and there is a discrepancy in what the full charge is. John is waiting for your pressures

[Jonas]

I don't recall your mentioning pressures. With the 16-ounce charge, what do the high and low sides look like at 1,800 RPM engine speed, A/C on max, blower on medium, doors and windows open, cooling fans running, and compressor engaged?

Here are the pressures at 80 degrees outside, doors/windows open, max recirculate/medium high fan:
Static: 64 (low side) 122 (high side)
Idle: 27-34 (low side) 170-190 (high side)
1800 RPM: 22-25 (low side) 200-210 (high side)
Vent temp (idle): 51 degrees
Vent temp (1800 RPM): 46 degrees

The pressures were moving around some, I guess because the RPM fluctuated at idle. The RPM also fluctuated somewhat at 1800 with the fans kicking on and off.

I hope this helps. With my rudimentary understanding or car AC, it just seems low on charge.

[tbirdtbird]

Rest of system seems to be properly intact.

Static pressures ( AC system off) should be equal not sure what is up with that.
Other pressures seem lower than they should be.
Maybe the charge capacity that John Here came up with is closer to being correct,
I agree it seems low on charge
This is a variable displacement compressor, I am not qualified to make judgement on that.
Let's see if Tim or John Here or one of the other mods thinks you should go with the amount John arrived at