2004 Mazda 3 AC Evaporator Temperature Sensor Replacement

[00scrub]

I was wondering if anyone here had any tricks to replace the Air Conditioning Evaporator Temperature Sensor on a 2004 Mazda 3. My AC compressor won't engage with the AC button, but the clutch engages fine when given 12V and the relay operates just fine. I measured an open circuit on what I think is the temp sensor to the left of the passenger side fuse panel.
The shop manual wants me to remove the entire AC unit from the cabin which is a daunting task. I was hoping someone knew if I could separate out the heater case and evaporator case some and get to it.

 

[Jetronic]

Don't know about getting to the evapoator without splitting the unit, my experience with modern cars says no. But I would look to find the wires for the sensor and try tricking the ac into running, especially on a 21 year old car where dismantling plastics must be carefully considered.

 

[Chris142]

Don't know about getting to the evapoator without splitting the unit, my experience with modern cars says no. But I would look to find the wires for the sensor and try tricking the ac into running, especially on a 21 year old car where dismantling plastics must be carefully considered.

This. Sometimes you are better off leaving the bad part alone and putting a new one next to it without taking too much apart

 

[WobblyElvis]

The blower fan should be just upstream of the evaporator. Sometimes you can remove the blower and reach into the evaporator sensor.

 

[00scrub]

good point about the plastics. I have half a mind to just short it and do my own 5 min PWM cycle with the AC button.

Elvis, that's a good idea. I'll take the blower off and see if I can access it some.

 

[00scrub]

I poked around some today and realized I didn't want to deal with trying to take apart the entire dash to get to it. I did however find that I could access the front side of the evaporator core from the cabin filter maintenance hatch. I think I might jury rig a sensor in that way and just hope I can stick it to a colder side of the heat exchanger and it'll work with some error.
Anyone tried this before?

 

[michaelluscher]

https://charm.li/Mazda/2004/3 L4-2..../Service and Repair/Disassembly and Assembly/
https://charm.li/Mazda/2004/3 L4-2....ature Sensor / Switch/Testing and Inspection/

Maybe do what Fusion people do and unplug/cut the sensor out of the harness, then bridge to with an appropriate value resistor
Then you can manually control A/C compressor operation
It looks vaguely doable from the schematics, without pulling the dash
But I don't have the car in front of me

 

[00scrub]

Thanks for the pics. I've used the Charm.Li pages a lot sorting this crapbox out. I've thought about shorting the pins with a resistor, but it would be nice to have some margin on detecting if the evaporator is freezing over. I'm pretty sure the eventual driver of this car will forget to turn off the AC from time to time.
Where did you find that last pic of the temp sensor position?
I'm able to unplug the sensor with what I've taken apart already.

 

[michaelluscher]

Where did you find that last pic of the temp sensor position?
I'm able to unplug the sensor with what I've taken apart already.

It's in Evaporator case R&R
https://charm.li/Mazda/2004/3 L4-2..../Service and Repair/Disassembly and Assembly/

 

[00scrub]

Ah thanks. Looks like it just press into the core between the fins. I'll see if I can snake my hand onto the other side of it