AC not cooling at idle sorta cool while moving
 

working on the wife's old mini-van, she has a new vehicle so this will be the kids car as soon as they get license :eek:

2002 Dodge Caravan 2.4l single system
Here are my readings:
Static not running: Low 95 High 100

Outside Temp: 86F RH 68%
Running:
Low 65psi High 160psi
RPM 816 Vent temp 75F

RPM 2100
Low 50-55psi High 250-275psi
Vent temp 75F

Since I get at least 95psi static I would assume no system leaks, as none have been sighted.
I would guess the compressor is weak, I would assume that I need to replace compressor, drier/accumalator and the expansion valve...
from what I have read I don't think I have any blockage so I should be okay to not replace condenser and evap coils ?

I've never done auto AC work so any tips and guidance would be appreciated... I have a working gauge set and will get a vac pump, and will have the system professionally discharged....

I see on the placard what the 134a charge should be but need to check on the oil charge....

Well, I'm not a very good A/C Tech either, but...

Those pressures seem very high to me, specially the 2100 rpm !
Usually that's indicative of a Dryer blockage.
If I remember correctly, pressures should be about 35 lo, 135 hi when running.

I'm just guessing though, it's been a long time. :confused:

Are those readings just before the compressor cycles off? They are to high. A blockage in the ac system cause the low side to go into vacuum. It seems to me the condenser fan is not working correctly. Try running a water hose over the condenser while taking your reading if the pressures come down and the vent temp gets cooler then you have an air flow problem. On a correctly working system Average low side pressure is around 30 and high 180-190. Those numbers (especially high side) do change some based on outside temp and humidity but they are a good starting point.

As far as I could tell (couldn't honestly see the clutch) it was engaged the whole time...
The fans come on shortly after the AC is turned on and both pull strong, I can feel the warmth... I have not physically checked for any blockage between the condenser and radiator, but I have no reason to believe that there is...
The AC compressor does seem nosier to me when engaged....I've got time to explore and troubleshoot... I have pulled the relay for the clutch for now so it doesn't get accidentally used and shell out on me...

Went and removed the engine shroud covering my view of the AC clutch...
Put the gauge set back on, engine cold.
Not running, Static: Low 18 psi High 115 psi (completely different from what I saw the first post)

temp: 93F RH% 39
Engine RPM 830 (idle) a tad high as I just started it and the engine cold..
Low 18 psi High 220 psi (indicative of a low charge right?)
Vent temp 67F

RPM: 2077
Low 18 psi High 275 psi (indicative of a blockage ?!)
Vent temp: 74f

*Compressor engaged the whole time as far as I could tell* never saw or heard it cycle, though I did turn it off to make sure I knew what it looked like off:o

And finally, i think I had already lowered the idle back down and I had blasted the condenser with the water hose just to see...

Low 18 psi High 145 psi but I didn;t see if the clutch was engaged, but that reading would say no...

At this point, I'm about ready to try adding 1/3 of a can of 134a just to see what changes...

I either have a restriction, a bad compressor or a combination of sorts or maybe just a low charge...:rolleyes:

The suction side did get cold... and now that I write this I question if the low side gauge was fully seated and opened the schrader enough after starting it..:eek:

When engine isn't running, shouldn't both lo and hi be the same psi ?

Those other readings are crazy...
Both seem to me to indicate a blockage.

My boneheaded mistake... went and rechecked and this time the readings were much higher for the low...the low side connection wasn't fully activating the schrader....

Low 78 psi High 175 psi at idle

Low 62 psi High 205 psi at 2k rpm

I also noticed the suction side hot as heck after shutting off the engine and the low side rocketed dang near off scale....

I am pretty sure I need a compressor....