Yeah... I am definitely not getting that. Even when I forced the compressor on (jumped 12v supply to compressor) I was still .04-.06volts (40mV-60mV).I will check my van to see what the supply is with the sensor connected.
With the AC off, the sensor should return somewhere between 0.15 and 3V or so. With the AC running is will vary, but probably around 4V or so?
I'll check those pins when I get back home. What about pins on the back of the ATC? Which pins should those be plugged into?Lets get back to basics. What is the pin-out at the sensor? There are tiny numbers molded into the plug.
pin 1 should be BR/BL (ground)
Pin 2 should be BR/RD (sensor return)
Pin 3 should be RD/BL (5V supply).
This morning with the engine off, key on, I had about 1V between pins 1 and 2. After starting the engine and turning the AC on, this rose to about 2V. So the output voltage should rise with pressure.
I don't have another one accessible to me and not sure where I would get one cheap. The one I have in the was rebuilt last summer so was hoping that it wasn't the issue as most the voltage checked out... That is kinda what I am leaning towards now... ATCTough situation here.. what a nice guy mwd is! Reading through this I can’t help but ask if you’ve tried swapping in another, known to be good, ATC just to rule it out? Perhaps you did and I just didn’t see it. I’m gleaning that you’ve tested all the voltages and they seem to be good.... so frustrating!
First, obviously mwd understands the details here at a very granular level so it might be worth getting his input. I’m just looking at this from 1k foot level. When you had it rebuilt last time did that fix any issues? I’m wondering if there’s a ground issue within the pressure sensor circuit within the ATC.I don't have another one accessible to me and not sure where I would get one cheap. The one I have in the was rebuilt last summer so was hoping that it wasn't the issue as most the voltage checked out... That is kinda what I am leaning towards now... ATC
Haha funny you said that. I ordered a 5v transformer a few days ago to step down from 12-5v. Should be here today and hopefully that can rule out a sensor issue.If the sensor gets 5v on the right pins, it must output a voltage that makes sense. With just 5v and ground connected, does the sensor work properly? How about your spare? If the etc can't supply 5v, it's probably the atc. If the atc's five volr supply chip is out of spec, you could always get a nether 5v supply from someplace else and use it externally.
One being bad doesn't mean all are bad, but reflowing all while in there is common practice. Did you inspect the relay contacts closely? They have some history of failure....
So I did the two larger pins on the relay (re-soldered) Only ones looked bad, but hard to tell,
do you typically need to re-solder all 6?
As MWD said, check operating pressures. An added switch indicates previous problems so who knows what's really going on.... Now w key on (not running), fan switch in off position, I press ac dash button and blower fan runs ac LED lights up. start van AC compressor clutch doesn't engage, when I flip switch (added by previous owner) AC compressor clutch DOES engage, but doesn't get cold (at all)...
The Electric fan is enabled by engine temperature (over 221F?), high A/C compressor head pressure, or loss of CAN bus signal.... also front of rad electric fan doesn't run, but engine not too hot so maybe not supposed to come on yet???
The clutch gets 12 volts, but you know that.... Help, me, please to understand the diagnostic pathway. is my ACT [ATC] 5v bad (hence AC compressor clutch extra switch)??? or ??? is this related to line pressure switch???
See above.... what does it mean that electric rad fan not on??? (is that just not hot enuf))).
The electric fan running can be an indication of CAN bus issues, but the fact that it isn't running isn't verification that there are no CAN bus issues.... As I understand it CAN communication is ok otherwise electric rad fan would default to on??? (is that right). ????