AC Passenger Side Not Cooling Properly

I have an '05 truck with the independent split/dual heating/cooling controls for the driver's side and the passenger's side.
The problem I have is that the passenger side has limited cooling compared to the driver's side (which works great) even though both temperature controls are set to max. cooling. I suspected it might be a blend door and/or actuator problem based on articles I've read concerning 3rd Gen. HVAC issues.
What I've done to date is:
- Had the local Dodge dealership check into it. They recharged the system with freon, replaced a coolant line that had a leaky valve and considered it fixed. The differential cooling problem between driver/passenger side was still there.
- I had another shop address the issue with emphasis on the fact that the AC was cooling well and that it appeared to be a distribution issue on the passenger side. They pulled the dashboard/instrument panel and checked out the HVAC box. They found that all actuators were working properly and scoped the box. It was clear of any blockages or damage. They couldn't figure it out.
I would like to know if anyone has had this problem and know what the fix is or what to investigate further.
Any help or insights would be appreciated. Thank you.

 

I have single controls, not dual. Every time I have had a passenger side cooling problem, the cause has been low freon charge. This is a common problem. Both control types use the same evaporator. With a low charge, the passenger side will not cool properly because of the freon flow path through the evaporator. If you cannot do it, have another shop verify the ac charge. One of the shops is not doing their job.

 

I agree - have the refrigerant recovered and weighed for quantity. There is a rare and very hard to diagnose problem with the engine fan control on initial startup for the day for the early and mid third generation trucks. Some trucks received an update to the PCM or ECM to resolve this problem.

It can be a warm day and the engine is started the first time for the day and the AC is switched on. On very rare occasions the engine fan will not be commanded to engage for several minutes. Under these conditions the high pressure side of the AC circuit reaches 450 psi (no air passing through the condenser) and the relief valve dumps half of the refrigerant to the atmosphere. When this happens, it almost always happens without anybody noticing. Because there is a baffle in the evaporator housing that separates the driver and passenger side airflow (either single or dual air), the passenger side cooling is reduced because of the now undercharged system.

There has been extensive research done on this site about this problem. I had an opportunity to witness this event happen just after I put gages on a 2003 truck. I started the engine and switched on the AC. (The truck owner complained about warm air on the passenger vents, but the drivers side was cold.) By the time I arrived at the front of the truck, I saw the high pressure gauge approaching 400 psi. I quickly shut of the engine and began scratching my head. What was going on? I restarted the engine and saw the same thing happening, but this time I noticed the engine fan was not turning. I shut the engine off and restarted it a third time. This time the engine fan was turning at a normal speed and the high pressure gauge stabilized at 125 psi. I recovered the refrigerant - the system was only at half of the posted capacity.

I'm not saying that this is your problem, but if it is, it will be hard to diagnose. The first step would be to recover and weigh the refrigerant to determine if any has been lost.

- John

 

Mine was low on refrigerant when it showed the same behavior.

Charge it by weight only! - as the pressures are pretty of the (normal) scale in the Gen3 system.
Low side shows always low even with the system heavily overcharged by 50%.

If you need to do it DiY then get an octopus* and not only a Can with a low side gauge.
You need to monitor the high side on that system.

*and properly bleed the hoses from any air prior to charge, air in the system will ruin the cooling capacity badly, more then one can think.

 

I use the procedure and the bands below in the chart to add to existing charge. I get satisfactory results without evacuating the system.

A/C PERFORMANCE TEST

WARNING: REFER TO THE APPLICABLE WARNINGS AND CAUTIONS FOR THIS SYSTEM BEFORE PERFORMING THE FOLLOWING OPERATION. FAILURE TO FOLLOW THE WARNINGS AND CAUTIONS COULD RESULT IN POSSIBLE PERSONAL INJURY OR DEATH .

NOTE: When connecting the service equipment coupling to the line fitting, verify that the valve of the coupling is fully closed. This will reduce the amount of effort required to make the connection.

1. Perform the A/C System Performance Test found within the HVAC System Test. If no diagnostic trouble codes (DTCs) are found in the A/C-heater control or the powertrain control module (PCM), go to Step 2. If any DTCs are found, repair as required, then proceed to Step 2.
2. Connect a tachometer and a manifold gauge set.
3. Set the A/C-heater control to the Recirculation mode (max-A/C) position, the temperature control to the full cool position, and the blower motor control to the highest speed position.
4. Start the engine and hold the idle at 1,000 rpm with the compressor clutch engaged. If the A/C compressor does not engage, see the A/C Diagnosis chart.
5. The engine should be at operating temperature, the doors should be closed and the windows opened.
6. Insert a thermometer in the driver side center panel outlet and operate the A/C system until it stabilizes.

NOTE: The A/C compressor clutch may cycle, depending upon the ambient temperature and humidity.If the clutch cycles, use the readings obtained before the clutch disengaged.


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Performance Temperature And Pressure

 

Ozymandias and jghflys,

Thanks for the additional feedback. I will pass on all this information on to the shop manager when I drop the truck off for servicing this coming week.
Two of the reasons the shop didn't figure out the problem is that: (1) I told them the system had been recently serviced and charged by the local dealership. Hence, they didn't check the charge and assumed if the driver's side got cold there wasn't a coolant charge issue. Since the dealership servicing, I may have lost freon without realizing it. (2) Also, the shop was not aware of the specific issues associated with the Dodge 3rd Gen. HVAC system that you guys brought to light in this discussion. They will now.
Thanks again for the help. I will keep check for any further comments and post my results to let you know how things progress with the upcoming work. My wife is not happy with the prospects of a July trip to Tucson without a fully functioning AC.

 

Likewise, my wife is my low refrigerant alarm in my truck.

 

Idling with ac on, fan barely turning, and high pressure side of 450, would probably indicate a defective electric fan clutch. Needs air flowing through radiator to lower the high side pressures, and for some weird reason cool on both sides.

 

Same here with a low refrigerant charge on my 05.

Found out the passenger side wasn’t cooling too well when I was in AZ for some training and my dad came to visit. It was 126° that day. My side was cold, his wasn’t.

 

If this is referring to my earlier post, this is not the case. In the condition I am referring to, the fan clutch does not receive the command from the PCM to operate, and the the signal from the high pressure switch to open the circuit to the AC clutch is ignored by the PCM.

If this is not referring to my earlier post, please disregard.

- John

 

Look at the oil filter… It gets painted with refrigerant oil and dye when the compressor high pressure safety relief valve opens somewhere over 450 psi. The following assumptions are it blew 1/2 the refrigerant charge out the relief vs. Leaks elsewhere.

Causes are the 2003-2007 A/C system doesn’t shut off the compressor if the cooling fan isn’t working. It can be a lack of “morning sickness”: the rare time it isn’t running on engine start, over 5 year old fan clutch that’s too slow to respond to commands yet can still not overheat the engine, clogged condenser fins…

Replace the fan clutch if it’s over 5 years old with a MOPAR part. Or not and then replace the A/C system from overheating and extreme head pressure and finally replace the fan clutch too…

Some strap an electric fan on the condenser… others don’t run the inside blower on high till they hear the engine fan come on. It’s difficult to work around a missing high side cut off switch: but I got it down to only needing a charge 2X a year in our extreme temperatures .

 

On my 2005, the PCM shuts off the compressor at about 420 PSI. I have watched it cycle many times. If that is not working, I would suspect the transducer. Our compressors are mounted low in the system and are subject to "slugging" on startup if the ac has not been run for a few hours. I installed one of these. https://www.4s.com/en/marketing/the-deslugger

 

@jghflys is yours a CA emissions model by chance?

 

From what I've seen that's more a problem with the Hallal Compressor, not so much with the Sanden that was used up to 2005 around.
At least mine never sprayed Freon, even at 50% overcharge.

 

No, label says that it complies with US EPA emissions regulations for model year 2005. Made in Mexico, shipped to Texas.

 

50 state 5.9 from 04.5-07

 

Yep all the Cummins engines were the same. California still required that every truck sold in California be tested and the trucks were identified as such. Federal emissions trucks were randomly tested.