Here are some things to check:
1. Use your hand to feel the temperature of the low pressure return line. That is the metal pipe with the muffler in it. It is on top of the engine compartment on the drivers side. There is a Schrader valve on that line. With the a/c set on maximum cool, that line should feel cold. If that line is cold, then your evaporator coil is probably cold also. So the problem is probably with the air ducts or maybe with the hot water cut off valve.

If that line is warm, then you have a problem concerning the refrigerant side of things.

It's not a good idea to run the A/C system for too long if that low pressure pipe is not cold. You could have a restriction in the line somewhere that is not allowing the refrigerant to flow. This would also stop the lubricating oil from flowing through the system so your compressor might not be getting enough oil. Also the low temperature refrigerant is supposed to be flowing into the compressor to help cool it.

2. See if the A/C compressor is running. The center part of the A/C pulley should be turning, probably need a good flashlight to see this. That is the clutch for the compressor. If only the outer part of the pulley is turning then the compressor is not running. Usually this is caused by not having enough refrigerant in the system to trigger the low pressure sensor.

3. If the A/C compressor is running, carefully check the temperature of the high side pipe. There are two metal tubes going into the compressor. The larger one is the low pressure return line. The smaller one is the high pressure line going to the receiver/dryer mounted behind the front grill. Watch out for moving parts like belts, pulleys and fan blades. Touch the high side pipe near the compressor, it should be very hot. If it is, then your compressor is probably working ok. If it is not hot, then maybe your compressor is broken, or maybe there is not enough refrigerant in your system.

4. Check the temperature of the receiver/dryer. Remove the four screws that hold the front grill. The receiver/dryer should be near the left side headlight. The receiver/dryer and the pipes going into and out of it should be warm. If any part is cold, then you have a restriction in the receiver/dryer or in the high pressure line.

5. Check the temperature of the high pressure lines. All of the high side of the system should feel hot or warm. All of the low pressure side should feel cold or cool. The expansion valve separates the high pressure side from the low pressure side. The expansion valve is mounted on the evaporator coil inside the passenger compartment. So the high pressure lines that go from the condenser coil in front of the radiator and back to the firewall should feel warm. If any part of the high pressure line feels cold, then you have a restriction at that point.

6. Check that the radiator fans come on. This blows air across the condenser coil in front of the radiator. It removes heat from the refrigerant and causes it to change from a gas to a liquid.

7. If everything checks out ok, except that the low pressure pipe is not cold, then here are some possibilities:
a. Not enough refrigerant.
b. Too much refrigerant.
c. Expansion valve is restricted.

Let us know what you find.
Terry

--- In CateraOwners@ yahoogroups. com, jbeardjr@... wrote:
>
> Terry,
>
> I'll run those checks for a major temp drop,but can tell you that I'm not 'seeing' nearly that much of a reduction,humidity notwithstanding.
>
> So, what would preveent a fully charged,pressurized system from cooling efficiently?
>
> John
>
>
>
>
> ____________ _________ _________ __
> From: trwong2000 <trwong2000@ ...>
> To: CateraOwners@ ...
> Sent: Thursday, July 9, 2009 1:18:50 AM
> Subject: [CateraOwners] Re: "Analysis,Mr. Spock"... .A/C NOT COOLING! (SOMEWHAT)
>
>
>
>
>
> I keep an instant read pocket thermometer with a 1" diameter dial inserted into the center vent of every car that I have. The thermometers are about $3 at Harbor Freight Tools.
>
> With the blower fan on high and the air coming from outside (not on recirculate) you should get about a 35° temperature drop. In other words, if the outside air temperature is 85° you should get 50° or lower out of the center vent. A really great air conditioner system can achieve a 50° temperature drop.
>
> With an outside air temperature of 80° and the fan set on LOW SPEED on my 97 Catera I can get an outlet temperature of 27°. All of the above temperatures are assuming a relative humidity of 30% to 40%. If your humidity is higher, you won't get as much cooling.
>
> Terry
>
> --- In CateraOwners@ yahoogroups. com, jbeardjr@ wrote:
> >
> > John W.
> >
> > I plan to se my temp gun to check the maximum cool temp coming out of my a/c; I feel that the coolder the air, the quicker the cool,no matter the heat.But if it isn't 'cold', then the temp drop is less,and takes longer to cool.
> >
> > Granted, I have no tint, but my '95 240 SX gets cold even w/o tint on the same days!
> > In all, I feel the system should perform better, hence need ideas on possible problems,solutions.
> >
> > Thanks!
> >
> > John B.
> >
> >
> >
> > ____________ _________ _________ __
> > From: John Williams <john05636@ ..>
> > To: CateraOwners@ yahoogroups. com
> > Sent: Tuesday, July 7, 2009 11:57:06 AM
> > Subject: Re: [CateraOwners] "Analysis,Mr. Spock"... .A/C NOT COOLING! (SOMEWHAT)
> >
> >
> >
> >
> >
> > i just did the a/c�recharge and mine don't seem cold but is cool on hot days�over 90 and i use the reciclate mode so no hot air can come in next is window tint� 15% should drop it even more! i�ran my a/c this morning and froze me out! but it�was 84 not 94?
> > �
> > John Williams.
> >
> >
> >
> >
> > ____________ _________ _________ __
> > From: "Pernesky, Dave" <dave.pernesky@ safholland. com>
> > To: CateraOwners@ yahoogroups. com
> > Sent: Tuesday, July 7, 2009 7:08:37 AM
> > Subject: RE: [CateraOwners] "Analysis,Mr. Spock"... .A/C NOT COOLING! (SOMEWHAT)
> >
> >
> > Have you made sure that the air duct vent (outside)is closed so the cabin air is recalculating?
> > �
> > David
> > �
> > From:CateraOwners@ yahoogroups. com [mailto:CateraOwner s@yahoogroups. com] On Behalf Of John
> > Sent: Tuesday, July 07, 2009 2:33 AM
> > To: CateraOwners@ yahoogroups. com
> > Subject: [CateraOwners] "Analysis,Mr. Spock"....A/ C NOT COOLING! (SOMEWHAT)
> > �
> >
> >
> >
> >
> > Guys, need your collective thoughts....
> >
> > Got my a/c system recharged after compressor replacement, but since then,it doesn't seem to cool as 'cold' as before.The amount of refrigerant, I/O pressures ,ect all are correct;changed the dryer/ accumulator, oriface tube....but still, with this hot,humid SE TX heat, I'm barly staying cool.
> > After a long drive, 20 miles or so, it starts to seem like its breaking the temp down,but just enough to keep the windows up,know what I mean?
> >
> > Thanks in advance for your input.
> >
> > John
> >
>