I have a 2007 Chrysler Aspen with 80K miles.
When we turn on the AC, a slight foul odor comes out of the vents, kind a musty smell.. Then it blows air that is not very cold, just cool. The rear air is much cooler, considered cold.
Do these symptoms sound familiar? I was going to check pressures but the rear is cold so I figure my refrigerant is ok.

Edit: This is a system WITHOUT driver/passenger side separated temp control.

 

This odor may be the result of microbial growth on the cooling coil. During normal A/C system operation, condensation forms in and around the A/C cooling coil. When airborne pollutants mix with this condensation, bacteria and fungi growth begins and odor may result. Odor may be noticeable with the HVAC system on or off. On models equipped with a cabin air filter, remove the filter and inspect for dirt and debris. Clean any dirt and debris that may be present at the HVAC fresh air inlet screen and at the top of the cowl panel. Inspect the evaporator drain hose or tube (depending on application) for foreign material that may be blocking the drain.

There is also a TSB regarding warm A/C symtoms:

TSB 24-003-07

SUBJECT:
Only Warm Cabin Air Output From HVAC System

OVERVIEW:
This bulletin involves the infrared (IR) temperature sensor used on automatic temperature
control (ATC).

MODELS:
2007 (HB/HG) Durango / Aspen

NOTE: This bulletin applies to vehicles equipped with an Automatic Temperature Control system (sales code HAB for JS or HAF for HB/HG) and built on or before March 27, 2007

SYMPTOM/CONDITION:
The customer may notice, while in automatic temperature control mode, that the driver and
front passenger cabin air output from the HVAC system remains warm. Adjusting the
HVAC temperature settings, while in the automatic temperature control mode, to a cooler
temperature will not change the warm cabin air output. The warm cabin air output can also
occur when operating in manual temperature control mode, with the exception of the full
cold (LO) temperature selection.

When in automatic or manual temperature control, all HVAC modes (defrost, floor, bi-level,
etc.) operate as designed. This condition may be due to the HVAC system infrared (IR)
temperature sensor that “locks” at one temperature and fails to change.

Hope this info is helpful to you and/or another forum member!

 

Now that I have checked more closely, the temperatures are the same front and back. Blows cool enough when outdoor temps are 80 and below, but in the afternoon when temp gets close to 90, it blows somewhat cool but not cold.

I am now assuming it is low on refrigerant.

I found the plate on the compressor.
High side: 3.53 MPa
Low Side: 1.67 MPa

This converts to:
High side: 512 PSI
Low side: 242 PSI

Is this correct??

EDIT: These obviously are NOT correct, I put my gauges on it and the low side was at 30 PSI.
My fitting would not go on the high side so I will order what I need to monitor the whole system before I try any adjustments, adding refrigerant, etc...

 

Suction Pressure at Service Port (Low Side)
138 to 310 kPa (20 to 45 psi) at (70° F)
138 to 345 kPa (20 to 50 psi) at (80° F)
207 to 365 kPa (30 to 55 psi) at (90° F)
207 to 414 kPa (30 to 60 psi) at (100° F)
241 to 448 kPa (35 to 65 psi) at (110° F)
Discharge Pressure at Service Port (High Side)
1034 to 1724 kPa (150 to 250 psi) at (70° F)
1379 to 2068 kPa (175 to 300 psi) at (80° F)
1551 to 2241 kPa (175 to 325 psi) at (90° F)
1724 to 2413 kPa (250 to 350 psi) at (100° F)
2068 to 2758 kPa (300 to 475 psi) at (110° F)


Low psi Control A/C Pressure Transducer A/C liquid line mounted - input to FCM - opens below 193 kPa (28 psi), closes above 234 kPa (34 psi)
High psi Control A/C Pressure Transducer A/C liquid line mounted - input to FCM - opens above 3275 kPa (475 psi), closed below 1999 kPa (290 psi)
A/C Clutch Coil Draw 2.2 - 4.0 amps @ 12V ± 0.5V @ 21° C (70° F)
A/C Clutch Air Gap 0.35 - 0.60 mm (0.014 - 0.024 in.)

Humidity has an important bearing on the temperature of the air delivered to the interior of the vehicle. It is important to understand the effect that humidity has on the performance of the A/C system. When humidity is high, the A/C evaporator has to perform a double duty. It must lower the air temperature, and it must lower the temperature of the moisture in the air that condenses on the evaporator fins. Condensing the moisture in the air transfers heat energy into the evaporator fins and coils. This reduces the amount of heat the A/C evaporator can absorb from the air. High humidity greatly reduces the ability of the A/C evaporator to lower the temperature of the air.

However, evaporator capacity used to reduce the amount of moisture in the air is not wasted. Wringing some of the moisture out of the air entering the vehicle adds to the comfort of the passengers. Although, an owner may expect too much from their A/C system on humid days. A performance test is the best way to determine whether the system is performing up to design standards. This test also provides valuable clues as to the possible cause of trouble with the A/C system. The ambient air temperature of the vehicle and the location where the vehicle will be tested must be a minimum of 21° C (70° F) for this test. Also the evaporator temperature sensor must be a minimum of 18° C (65° F) for this test as well.

 

Thank you, this is very valuable information.

I did add some refrigerant while monitoring only the low side. (92 degrees, high humidity). I brought it from 30PSI to 45PSI, I did not want to add more without having a gauge on the high side. It started blowing cold again but it started short cycling while idling the other morning, short cycling like every 2 seconds or so. According to your chart, considering temp and humidity, I could have gone to 55PSI.

I ordered a brand new set of high quality gauges to see what is really going on.

Is it normal to lose refrigerant like this over 7 years? or should I start looking for a leak? I live in a very hot and humid environment (Mississippi).

 

7 years, 80K miles, Hot Humid Environment..........I wouldn't consider needing refrigerant abnormal. If it starts to lose refrigerant more frequently after the refill then I would start to worry about a leak.

Good luck on getting everything squared away soon! Be sure to post the results after you get the gauges.

 

I charged the system and got it working adequately but I suspect I may have not gotten it charged completely. I charged it to where it stopped short cycling but it started doing it again today, not sure if refrigerant leaked or if it was because we had a hotter day (95 degrees).

Is it OK to use the refrigerant that claims to have "stop leak" and Oil additives? Will this harm the system or even help if I really do have a leak?

EDIT: The product I am considering is "Arctic Freeze" "Ultra Synthetic" with "Advanced Leak Sealer and Moisture & Acid Eliminators"

 

I have not heard of any issues with the use of "stop leak" and Oil additives.