QuestionQUESTION: Hi Kevin, A few weeks ago you helped me find the evaproator temp sensor on my early model year 2004 pacifica- thanks for that info- My problem is this- the a/c does not run or it short cycles. I scanned with a DRB and found the evaporator temp sensor reading around 38 deg when ambient is around 80 deg. I got a new sensor and unfortunately it reads the same as the old one. I am suspecting a wiring resistance problem or controller issue. the current voltage reading in the DRB is 2.35 and reading around 35 deg when it should be 80 deg. Any suggestions as to where to look next? where is the HVAC body controller located?
Thanks
ANSWER: ambient temp is outside air that is how warm it is outside of the car has nothing to do with temp coming out of the evap. The evap prob is designed to measure the temp of the evap and keep it right around freezing if it shows 35 then its doing its job.
do u have to much freon in the system or not enough?
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QUESTION: the 35 deg readings I am getting are without running the a/c -- the car has been shut off all night and the evap sensor is reading in the 30's- if the compressor does turn on it drops to 28 and shuts down in about 10 seconds. I figured the resistance of the sensor was going bad but the new sensor is reading the same as the old one. The freon levels are correct. If i remove the sensor from the H-valve and let it hang in the engine compartment the a/c will come on and work well.
ANSWER: are u reading the sensor for the ambient temp or the evap prob in the dash?
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QUESTION: my pacifica, as you showed me in the response to my inquiry on 8/1/09, has the evaporator sensor mounted to the expantion valve on the engine side of the fire wall. it is an early 2004 production. this is the sensor that will cycle the compressor to keep the evap from freezing up. It shows up in the DRB as evaporator volts and evaporator temp degrees. if I unplug the sensor the evaporator volts goes to 5 volts and degrees shows no reading. with the sensor pluged in and car has not been run, the sensor degree reading is about 40 degrees cooler than it should be, therefore as soon as the compressor starts running, the sensor reads too cold and shuts the compressor off. If i remove the sensor from the expantion valve and let it hang in the engine compartment, the a/c will run because the sensor is not getting colder, but it will not cycle either causing the possibility of freeze up. new sensor reads the same as the old one. all the other temp readings in the system seem normal
AnswerThe 5v is normal its a signal wire. next u would want to see if the wire itself has an issue or if the ac control head is the issue. being that U have early production I only see one wire diagram for it so it either goes to the PCM or the AC control head. If u get the evap temp in the pcm screen then U know that's where u will need to look.
Get a volt meter with and one that can read resistance ohms. Unplug the sensor and then unplug the other end either at the pcm or at the ac control head then probe on end and the other to ground with the ohms U want OL if u get any resistance on it then U have a wire touching ground where it is not suppose to be. DO this for both wires. If the wires are good bad controller. either pcm or ac control head.
