A little A/C help please

I tried to recharge my 996 today as the A/C wasnt blowing cold at all. Bought an recharge can with pressure gauge, accounted for the temperature and charged to ~35 psi. The temp at the center vent didnt change at all. I checked the compressor and when the "Snow flake" is on the compressor is engaged the whole time. Once it was charged, the pressure gauge oscillates between 25-30 psi. There is also a venting sound from the area by the pressure ports and expansion valves., you can hear it inside the cabin even at full blast. There's no noise when the A/C "snow flake" is off, only when the A/C is running. Any ideas?

what is your pressure on the low side vs the high side?.. Is maybe your heater valve stuck open?

I know the low side is ~25 to 30 psi. I dont have a fitting to measure the high side. Is there a way to test if the heater valve is stuck open? The sound is similar to opening a scuba tank valve and hearing the gas surge through the manifold/piping. At first I thought the evap core or something within the unit was leaking, but the sound is only there when the AC is on specifically (i.e. snowflake), it completely goes away if the AC is turned off. Would the the expansion valve make such a noise if it was faulty?

HELLO, I tried to recharge my 996 today as the A/C wasnt blowing cold at all. Bought an recharge can with pressure gauge, accounted for the temperature and charged to ~35 psi. The temp at the center vent didnt change at all. I checked the compressor and when the "Snow flake" is on the compressor is engaged the whole time. Once it was charged, the pressure gauge oscillates between 25-30 psi. There is also a venting sound from the area by the pressure ports and expansion valves., you can hear it inside the cabin even at full blast. There's no noise when the A/C "snow flake" is off, only when the A/C is running. Any ideas? -------------------------------- brianmorgan PLR Rights

Did you charge it with the snowflake button on and AC blower high? I just recharged my 2001 Durango R/T today...have done quite a few cars over the years. If you want to check for a leak...get the one with dye in it and a UV light. If you charged it with the above steps and it is not blowing cold....I would take it to a HVAC guy. You can damage the compressor...most expensive part if you do something wrong.

Your car regulates the air temperature flowing into the cabin via a reheat/remix method. ALL system airflow is first cooled (pretty seriously so,<35F, at low blower speeds) and the routed through the reheat/remix plenum area. In the wintertime ALL of teh airflow is likely routed through the heater core, summer time ALL flow bypasses the heater core. The position of the blend door is the determinist factor regarding the temperature level of the airflow into the cabin. If the blend door is stuck in the full hEAT position.... There is no valve to control the HOT coolant flow to/through the heater core. My '01 C4 has a coolant flow restriction (OFF/ON) valve I puchased at Home Depot, I keep it turned off throughout the summer season. I also have a manual switch in a hidden mount area that I use to disable the A/C clutch during heating season.

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With these new AUTOMATIC climate control systems you should not expect COLD airflow once the cabin is first cooled down to nearby your temperature setpoint. Setpoint, say, is 72F, cabin has now been cooled down to ~75, then the system cooling airflow will not go much below 65F, if even that. These new systems are more about avoiding the discomfort of COLD outlet airflow, of TOO HOT outlet airflow, than they are about RAPID initial cooldown or heating up. Also, once the cabin is cooled to nearby the setpoint the windshield system outlet flow will open to more evenly distribute the outflow and thereby avoid so much cool discomforting airflow directly to your face and upper body. This can result in inordinate cooling of the windshield and formation of fogging on the outside. Not much of problem in the daytime but at night or at dusk it can creep up on you and be a danger. The best practice is to ALWAYS override the system by manually selecting system outflow, DE-SELECTING windshield outflow. A second, even more hazardous outcome of all this is the lack of HEATING airflow to the windshield if you need to switch to defrost/defog/demist position once the cabin is acclimated to your temperature setpoint. If you for some reason need to defog/demist the interior surface of the windshield in this situation then you MUST quickly run the cabin temperature setpoint up to max to get HEAT to the windshield. Lastly: I have found that in the summer months in your area of the country (more like TN, AR, and MS) to get good cooling I turn the setpoint to maximum cooling and then use the blower speed to regulate my comfort level. But this will result in REALLY COLD, sub-40F, system outlet airflow so avoiding airflow to the interior of the windshield becomes much more important. Learned that lesson driving across AL just after dusk one HUMID evening after a HOT summer day. At first thought my headlights were getting dimmer and dimmer....