A/C won’t run need some insight with diagnosis

[Skytow]

2001 Z3 3.0 roadster

Been trying to get my AC working again as it has been super hot these summer. Since it’s been some time since it worked I assumed (yep, I know...) it was simply a slow leak and the charge was low. All I could get was a static charge reading as the compressor won’t kick on. It looked ok and would not take any 134.

I put my new Foxwell scanner on and got an error for radiator outlet temp sensor. You can see it in the attached40B8FE5C-514F-4038-B404-0303173C81A2.jpg

I ordered and installed the new sensor and can clear the code and my AC runs cold for about 30 seconds and stops. I get the same code again. Am I on on the right track to start looking for a wiring issue for the sensor to DME or should I be looking elsewhere? I should add the electric fan is running so I think the fan is fine. Thanks.

[BimmerBreaker]

You replaced that sensor? Howd you do that? What sensor did you replace exactly?

[KBH22102]

Was your AC running the same way before you cleared that code (30 sec of cold, then stop)? I don’t think your AC system has anything to do with engine cooling system.

I am also diagnosing AC issues in my 01 and I think the correct starting point is to measure your AC line pressures with a manifold gauge. 5BE66628-3ACC-4B23-8B02-A811C2D21FB2.jpg

[rf900rkw]

You know the answer. The DME has a shadow code for the missing E46 radiator outlet sensor.... because it's in an E36. So he replaced the radiator fan switch.


"But the COMPUTER said" ... right up there with "I was torquing it to specs when it just broke"

OP, what are the system pressures? "looked good" is not something that can be diagnosed. And before diving into overcharging the system, as the DME software been changed / "tuned"? If you have an E46 tune, that code will set as a hard code rather than just a shadow code, and the system will not work.

[BimmerBreaker]

You know the answer. The DME has a shadow code for the missing E46 radiator outlet sensor.... because it's in an E36. So he replaced the radiator fan switch.


"But the COMPUTER said" ... right up there with "I was torquing it to specs when it just broke"

OP, what are the system pressures? "looked good" is not something that can be diagnosed. And before diving into overcharging the system, as the DME software been changed / "tuned"? If you have an E46 tune, that code will set as a hard code rather than just a shadow code, and the system will not work.

You're right... I knew all along...

The possibility of a non-Z3 flash on his DME crossed my mind as well - but as I remember on my E39 when that aux fan broke, the A/C would not cut on AT ALL, not for 30 seconds, not for any amount of time, without the aux fan working. So if that is a hard code, not a shadow code like it should be, then I dont think the A/C would be operating at all. Though I do think ambient temps come into play as well as other factors, so its possible in a cooler climate he gets some run time before the DME wants the fan on, then it shuts A/C off when it detects it isn't there. BUT it also should test the PWM fan (if its a non-Z3 tune) at startup - and that usually has it's own "e-fan failure" code if it isnt working, which triggers the A/C to not come on if that code is present. So I have to imagine the DME tune is correct for the Z3 and thats just a shadow code like it should be.

If its working in 30 seconds bursts, I would check the reading while its working

[Skytow]

Guys appreciate the suggestions and am willing to learn. Newb here when it comes to AC repair so bare with me..... you gave me lots of homework to do and I will tear into as time allows.

I did hook up the ac gauges but, at the time could not get the compressor to come on. I could only read the static pressure. That said it would not take any 134 as is. I figured out the code subsequently and found if I cleared the radiator outlet temp code the ac would in fact run and blow cold but only for about 30 seconds or so. Then the code was set again and ac compressor would not engage.

So yes I believed the code for what I thought was the radiator outlet temperature Sensor and have replaced what amounts to a fan switch. It did seem reasonable that if the car thought it could not either read that temp or turn on the fan that it would not allow the ac to run.

I’ll do a better job getting the pressure reading while manually activating the compressor next and get you all some Actual data on the high and low sides.

The car DOES have a tune so it sounds like I need to check on that and any potential impact next. When I do,what specifically is the question is should ask? Would it be “is this an E46 tune?”

thanks a million for the help!

[BimmerBreaker]

Talk to the tuner and ensure the tune was for a Z3. Who did the tune?

[rf900rkw]

I believe, from researching your PWM fan quest, the E39 and the E46 handled A/C request and commands differently.

Yes, if the car has been tuned and the A/C hasn't worked correctly since, that is a good place to look.

[Skytow]

Tune was by Epic Motorsport in FL.

[Skytow]

Ok back with some photos of the A/C gauges first static and one with a/c clutch engaged. Sorry for the delay was hosed by Isaias!

I still need to follow up on the tune butsame symptoms persist. I can, via the scanner, turn on the A/C for 30 seconds which is how I got the picture or clear the codes and it runs for about 30 seconds. It does blow cold when it runs!

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[rf900rkw]

Something very wrong with those pictures. you can't have 40/40, then 190/30. I would say it's low on freon land tripping the low pressure switch. But the numbers don't jive.

[BimmerBreaker]

That blue gauge has a zone (on the very upper reaches) all for me

[Skytow]

Lol on the upper range. Thanks for the guidance.

[rf900rkw]

That blue gauge has a zone (on the very upper reaches) all for me

Funny, I got called that last night when trying to explain pre-algebra to some loudmouth. 2+2 can indeed equal 3, just nail two 2x4s together and measure.