Ok, sometimes at slow speeds or idle my AC will not blow cold. But as I drive fast it seems it will blow cold. First thought is the AC condenser fan right? But I have checked the fan and every time it is working.

So I thought is was maybe because my idle was set at around 625 or so so I bumped it up but it still will occasionally do it.

So I bought a can of synthetic r134a and a gauge like the one below. But when I connect the gauge to the low side of the system I read 40psi.

The label under the hood reads 1lb 10oz. Without real AC gages, how much refrigerant should be in the system.

And does anyone have any logical idea of why it wold not blow cold at times?

 

Weed,

The 1# 10oz label under the hood is a full charge ---filled into an evacuated system. With 40 psi low side, without a temp/pressure chart, I would guess you are OK,
When you checked the pressure, its good to run it up to about 1K rpm to get a good reading.
It is possible you have the dreaded door problem.
Are you running it in recirc?
High humidity causes increased cooling load, and will increase the time it takes to feel the real coolness of the system---it has to wring the water out of the air first

 

My exploder does the same thing when I first start it up. It needs to be driven down the road before it goes cold. I don't recall what the psi should read, but it should be in the normal area on the guage. If it's too high then you have a clog it seems??? Im def. not the A/C expert by any means.

 

I do a/c for a living on houses but r-134a with a gage outta read about 40 degrees on the r-134 scale on your gages. That might be around like 40 or 50 psi, just follow the scales at the bottom that mach the color of the refrigerant you are using so 134 is light blue I think. Crank the a/c and rev the motor a bit to get the compressor moving.

 

I just did this a couple weeks ago on mine and 40 psi is fine, I'm at around 33-35 which is a little on the low side for the over 100* daily temps down here but she still gets cold, takes half a mile or so to feel cold but it does makes it. Pressure shouldn't be the issue for you.

I would rev it up and see if gets colder at higher rpms that way you can at least knock out whether it is dependent on engine rpm or actual vehicle speed. I'd figure that out then take it from there, A/C systems are one of those pain in the *** systems that gremlins love to fruck with and sometimes us do-it-yourselfers just can't beat 'em.

 

https://dodgeforum.com/forum/3rd-gen...a-c-specs.html

 

you want static charge around the temp of the ambient air.
with the compressor running your low side should be around 30 - 40 psi
with the compressor running your high side should fluctuate between 150 - 250 psi.

chrysler calls for 2000 RPM's when checking with the compressor running

it is possible that your condesor is clogged with bugs or dented fins. try spraying the opposite way and see if its clogged, etc.

 

Well on this gauge Ive got (DIY Interdynamics AC kit) the green zone is anywhere from 25 to 55psi.

But what I was worried about was with me reading 40psi and adding freon, I didnt want to over pressurize the system even though anything from 25-55 was in the green zone. The paper that comes with the kit says with outside temps being 100* I should have 50-55psi but I didnt know if this was vehicle specific or universal to all vehicles. So again, I just didnt want to over pressurize and blow the seals or worse.

I guess I will pick up a can and see what I can get out of it. When I did my wifes in her Mini, she was at 25psi and I added a can and it only bumped her up to about 35psi so Im wondering how many cans I really need????

And is the cheap r134a as good as the fancy cans or this synthetic r134a??

 

make sure you get the proper R134a for the system. do NOT buy any with sealants or a additives. it will ruin your whoel system.
i have a set of professional gauges that help with diagnosing becuase you can see both pressures static and dynamic.
here is what my set looks like:

 

Yeah I know what real AC gauges are and look like but I have none nor do I need a professional set. I wonder if i can borrow some from work though.....hmm.....