Can someone direct me to any threads regarding air conditioner stopping blowing cold air after about an hour of continuous use? Mine works ok for about an hour, but then eventually acts like the coil is freezing over and preventing air flow. I can hear the fan blowing and it souns like it's blocked. If I turn it off, eventually it will start working correctly.

I had shop check pressure (front side & back side) and that is all up to spec. It's blowing about 20-25 degrees below ambient temp, so that seems fine. (for the first hour or so...) Then it just starts blowing less & less air thru till next to nothing is coming out of vents. I think if I turn off a/c, switch to outside air coming in, leave blower blowing ambient air it eventually starts moving air thru the vents again. It is acting just like when your coil freezes over in your house due to low freon. But it takes about an hour to do that...

It seems t be draining, but late last summer my passenger floorboard was getting real wet, like it was draining in the cab. But I did have water draining from behind & under the right front tire. So it is draining from where it normally does. Perhaps it's trying to drain way too much water for the normal drain? (if that even is possible...)

Any ideas / recommendations would be greatly appreciated. Sorry if this was brought up before, the thread search returned nothing for me.

 

Usually, having the system ice up is a sign of a low refrigerant level. Have it checked. Depending on the humidity and ambient temp, yes, it could take up to an hour for the system to ice over.

Also I believe we have a thermostatic switch that will cut off the compressor when the evaporator coils get down to a certain temp. That could also be a cause of the issue. If it's stuck, the compressor will just keep running till you turn it off.

Water on the floorboard? Doublecheck that the drain isn't blocked. Even a partially blocked drain can allow for water to back up and leak in to the cabin. Especially if there is a large amount of ice melting off the evaporator.

 

Sounds like it is freezing up.

 

I'm leaning towards the thermostat switch. They just had the refrigerant checked and is right amount. Any idea where the switch to shut off the compressor when coils get too cold is?

 

Take a gander at the parts manual. (You can get a copy in one of the stickied threads here). Heater and Air Conditioning Unit section.

They are calling it, "Probe, Air Conditioning". Not quite sure on how big a pain in the rump it's going to be to get to tho. Is covered in the service manual as well. (Also available here) 2005/6/7 Dakota Service & Parts Manuals.

 

Mine did this last year twice. Both times after an hour on the freeway, both times had water in the pass floor. I never did figure it out.

 

I have the same problem. It happens all of a sudden like a door is shutting. Are there any vacuum lines that control the vents? Can't find any info. I'll be driving along an all of a sudden no air coming from vent. WTH?

 

My wife's 2006 Durango would do this if you had it on any other setting besides max A/C. 3/4, 1/2, or 1/4 turn and after about an hour or a little less, it would act like something was blocking the airflow (but you could still hear the blower going). If on max, it never would act up.

After literally hours and hours of searching on the internet back then with different terms, I finally found the below snippit. Traded in the Durango before I had a chance to implement it. This service bulletin is for Durangos and Aspens, but it may apply to us as well, since our interiors are very similar. Minor note, I changed the formatting slightly to make it easier to read.

 

There are a couple more steps to the repair procedure listed in the TSB above. I am reposting the entire thing in case I missed anything else.

NUMBER: 24-004-10
GROUP: Heating & Air
Conditioning
DATE: April 7, 2010

SUBJECT:
No A/C Or Evaporator Freeze Up On Long Trips With Blower In Low Speed Position
OVERVIEW:
This bulletin involves adding a resistor 470 ohm resistor in the evaporator temperature
sensor signal circuit.
MODELS:
2004 - 2009 (HB) Durango
2007 - 2009 (HG) Aspen
NOTE: This bulletin applies to all HB/HG vehicles with A/C (sales code HAA or HAB
or HAF). This bulletin does not cover the 2009 HG HEV vehicle.
SYMPTOM/CONDITION:
The customers may experience poor A/C, little to no A/C operation or reduced airflow from
the instrument panel vents. This condition often occurs after a extended drive cycle
(greater that 2 hours) with the A/C on and the blower speed is set to the low position. Once
the vehicle is shut off or the A/C is turned off for approximately 2 hours the A/C will operate
normally.
Adding the resistor to the evaporator temperature sensor signal wire allows the A/C
Compressor to cycle at a higher temperature more frequently to avoid this condition.
DIAGNOSIS:
Using a Scan Tool (wiTECH™ or StarSCAN®) with the appropriate Diagnostic Procedures
available in TechCONNECT, verify all A/C systems are functioning as designed. If DTC's
are present record them on the repair order and repair as necessary before proceeding
further with this bulletin.
If the above condition is present, perform the Repair Procedure.

PARTS REQUIRED:
Qty. Part No. Description
1 68081530AA Kit, Resistor
Kit includes; 1 470 ohm resistor, 2 wire shrink wraps and
2 splice crimps.
REPAIR PROCEDURE:
1. Remove and disconnect the ATC or MTC control head. Follow the detailed service
procedures available in DealerCONNECT/TechCONNECT, Refer To Group 24 -
Heating & Air Conditioning > Controls, Front> Controls, A/C & Heater Removal
Procedures.
2. Using the wiring diagrams available in DealerCONNECT/TechCONNECT locate the
evaporator temperature sensor signal wire. Cavity 10 of the C2 black 12 - way
connector for ATC systems. Cavity 2 of 20 - way black C1 connector for MTC systems.
3. Measure 76mm (3 inches) down from end of ATC/MTC connector and cut the
evaporator temperature sensor signal wire.
4. Using the 2 splice crimps and 2 wire shrink wraps from resistor kit p/n 68064996AA,
splice in the 470 ohm resistor. Follow the detailed wiring procedures available in
DealerCONNECT/TechCONNECT, Refer To the Wiring Tab > 8W-01 - Wiring
Diagram Information > Wire > Standard Procedure.
NOTE: Be sure to use the splice crimps and shrink wrap on wires and resistor.
5. Install the ATC or MTC control head. Follow the detailed service procedures available
in DealerCONNECT/TechCONNECT, Refer To Group 24 - Heating & Air Conditioning
> Controls, Front> Controls, A/C & Heater Installation Procedures.
6. Using the wiTECH™ or StarSCAN® erase all DTC.
POLICY:
Reimbursable within the provisions of the warranty.

 

Thank you for your help!