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Good day Jeepers
My 2010 JK A/C has a weird problem that my local agent (South Africa) has not been able to fix in 6!!! workshop visits.
When I switch the A/C on it works fine, but after about 10 or so minutes there is less and less air coming through the vents, until there is almost nothing. What air does come out is still cold though. If I switch the A/C off for 5 to 10 minutes it works fine again until the cycle repeats.*
I think the evaporator is freezing up, especially since there is a lot of water under the car after the A/C is switched off.
I have found that the compressor clutch never disengages, however if I disconnect either the pressure transducer or the evaporator temperature sensor the clutch disengages. I have replaced the pressure transducer, the evaporator temperature sensor, the fan and fan resistor (all Mopar original parts) and regassed the system.
This is not a climate control system like in newer models, but an old style mechanical system, so no cabin temperature sensor. Oh, and there are no fault codes or warning lamps.
Does anyone have any idea what to look for next?
 

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The A/C coil is freezing up into an ice block and preventing air flow. I had this happen exactly as you explain it with my Jeep many times. Your A/C refrigerant is either low or has moisture in it. Have your A/C system evacuated and refilled. Make sure UV leak dye is also put in the system to detect any leaks.


Also make sure that your A/C drain hole is not plugged up. You can access it some where near the top of the transmission.



You can verify that the A/C is icing up by putting on the heater when it happens and looking for a lot of water draining out of the A/C drain. When the water stops flowing the A/C will again blow at full force.
 

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Agree with the freeing, but it shouldn't freeze even if ac is low. There is an evap temperature sensor on the evaporator which is supposed to start cycling the ac compressor as the temp drops to freezing. It's either extremely dirty or malfunctioning and needs replacing


DESCRIPTION

The evaporator temperature sensor measures the temperature of the conditioned air downstream of the A/C evaporator. The evaporator temperature sensor is an electrical thermistor (1) mounted on the end of a molded plastic housing (2) that is inserted into the driver side of the HVAC housing near the coldest point of the A/C evaporator. The evaporator temperature sensor is retained in the HVAC housing by two integral retaining tabs (3) and is connected to the vehicle electrical system by use of a wire lead and connector (4) with two terminals.
OPERATION

The evaporator temperature sensor monitors the temperature of the conditioned air downstream of the A/C evaporator and supplies an input signal to the A/C heater control. The A/C heater control uses the evaporator temperature sensor input signal to optimize A/C system performance and to protect the A/C system from evaporator freezing. The evaporator temperature sensor will change its internal resistance in response to the temperatures it monitors and is connected to the A/C heater control through sensor ground circuit and a 5 volt reference signal circuit. As the temperature of the A/C evaporator decreases, the internal resistance of the evaporator temperature sensor decreases.
The A/C heater control uses the monitored voltage reading as an indication of evaporator temperature. The A/C heater control is programmed to respond to this input by requesting the Powertrain Control Module (PCM) to cycle the A/C clutch as necessary to optimize A/C system performance and to protect the A/C system from evaporator freezing.
The evaporator temperature sensor is diagnosed using a scan tool (Refer to 28 - DTC-Based Diagnostics/HVAC - Diagnosis and Testing) .
The evaporator temperature sensor cannot be adjusted or repaired and must be replaced if inoperative or damaged.
If you have replaced the temp sensor already (and it sounds like you have) then it's most likely a pcm problem.


Now you COULD jury-rig the issue and create your own evap temp sensor instead of screwing with the pcm which could get expensive.


You said if you disconnect the temp sensor the clutch disengages.... so install your own temp sensor with a relay which effectively disconnects when the temp goes too far down. Temp controllers are CHEAP.
https://www.ebay.com/itm/DC-12V-50-110C-Mini-Thermostat-Plate-Switch-Control-Temp-Incubator-for/264291822545?hash=item3d89052bd1:g:2TkAAOSw4oFcu3c3
 

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My icing was caused when the system was opened for the V8 install and not evacuated or filled properly. A proper evac and refill solved my problem. I also had a leaky schrader valve.
 
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