Automotive Air Conditioning Information Forum (Archives)

mhfd112 on Mon June 10, 2013 3:34 PM

Year: 2005
Make: Dodge
Model: Dakota
Engine Size: 5.9

My buddies AC keeps freezing up on his truck. The low side was going down to 10 before it would cycle off. Changed the switch in the high side line, but it still freezes up. It cycled off at 21 with the new switch. High side was 150. Outside temp was 75. Vent temp low to mid 40s.

Any ideas?

mk378 on Mon June 10, 2013 5:54 PM

On a CCOT system, the switch on the accumulator (low side) controls cycling. The one on the high side protects against overpressure and may start the electric condenser fans (if equipped).

mhfd112 on Mon June 10, 2013 10:30 PM

I don't think there was a switch on the accumulator or low side line.

I will look again.

TRB on Mon June 10, 2013 11:54 PM

Proper charge level?

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mhfd112 on Tue June 11, 2013 2:52 PM

When I first looked at the truck I thought it might be low so I added 12 oz. it still froze up and didn't cycle off until it got down to 10 psi on the low side. I recovered 10.5 oz and installed new switch. Still freezing up and cycling off around 20 psi.

It probably doesn't have the correct charge, but it shouldn't be too far off.

94RX-7 on Tue June 11, 2013 8:04 PM

If this system is anything like what was on my 2005 Ram SRT-10 the "switch" you replaced is actually a transducer, and the evaporator temperature is monitored by a thermistor that reports evaporator temperature back to a computer (possibly the PCM) which then determines when to shut the compressor off.

iceman2555 on Wed June 12, 2013 12:31 AM

Adding refrigerant...removing refrigerant....not knowing how much is in the vehicle...testing pressures.....simply recover...evacuate and recharge to OE specs. This is the correct way.
This is a TXV system and does not have an accumulator or a LPCO switch. The evap temp is controlled by a thermomister/temp transducer located in the evap core. Should be accessible thru a small door located in the evap case under the glove box. This can be tested using cold water and a multimeter.

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mhfd112 on Sun June 23, 2013 12:07 PM

My buddy brought his truck back today. I recovered and recharged to factory spec. It was 5 oz low, but it's still freezing up.


We are gonna try to get to the thermistor in the evaporator. Only access I see so far is maybe taking the fan motor out.

mhfd112 on Sun June 23, 2013 1:23 PM

I don't a think we will be able to get to the thermistor.

I did stumble across a TSB for an 05 Durango. Has the same problem with evaporator freezing up. If I understood it right, the fix is to add a 470 ohm resistor in the wire going to the thermistor.

Has anyone else ran into this ?