Speaking of fracking, I bet that little chap is having probiscus thoughts, too !!! :D

Am not asking you how to operate multi CG---I read manual! Am asking you for S&G's what ramifications of 0.3 ohms is relative to that section of wire's responsibility within AC system?

PS - my fingers were on contacts/probes. Does that mean do-over? (I admire your detailedness.) BTW, went to your site and read through your troubleshooting section. Impressive coverage.

:eek:

Yer a naughty man, Karlicous - love it!

"Probiscus thoughts" ....LMFAO Rono!

Not sure if you did that intentionally or not but it's dammfunny (to my simple mind.)

^^^

100% intentional, word Tomfoolery on my part, Karl - ha ha!

Dearest Uncle Karl,
Again, my apologies. I'm simply never politically correct on Mondays.
I should have sat on the PARP.

So, your question is, assuming "I" am reading your new meter correctly.
Is a value noted a realistic value in the cases of:
1 = Probes touching, . 7 ohms = NO, should be 0
2 = Probes + extension wire, .9 ohms = Probably NO, but once you get "1" above to read 0, then measure the extension by it self and do the math.
3 = Probes + extension + green wire from T-switch back to power wire at compressor, 1.2 ohms = Probably NO, until you resolve "1" and "2".

There are:
Known knowns
Unknown knowns
Known unknowns, and
Unknown unknows.

^^^

Looks like a lot of touching and probing required to get the job done; I'm sure Uncle Karl is up :eek: to the task!!!

CircuscircusBro! SmileWavy


My upgraded multi is... instantly downgraded. It has NO tare. (I now realize some do.) Not sure if that is what you're suggesting for "0" value on connected probes. (Could tare both probe + extension.)

Will test again----without touching probes.

Unknowns are food for thought.

2nd resistance test - Checked meter with 2.7 and 220 ohm resistors to sort out dial settings and confirm meter working. (Was not set correctly for 1st test.) After testing resistors, tested:

1. Probes
2. Probes + extension wire
3. Probes + extension wire + green wire from cabin to power at compressor... and never touching probes.

O resistance for all. Given the 2.7 and 220 resistor tests proofing meter working to spec, green wire reading has to be correct. Is it possible there's zero resistance?

Within rounding error, yes. That's what I'd expect. It's not actually zero resistance, but it's lower than your meter can measure. I think that means you're good.

Since you asked, I have enjoyed reading your thread from the beginning, much less the PARF-ness lately. China- fine. We can all participate in that. I don't consider this forum to be one dimensional without politics injected. In fact, without the politics, many other things can bloom. Like friendship. Since you asked.

Karl,

Assuming a 12 awg wire, figure 0.016 ohms nominal for 12 ft run.
If you read the owners manual for the meter it might tell
you the rounding is to 1; exclusive of the accuracy of the meter,
room temperature, etc. PARF!

Dru... appreciate input including personal commentary. Always enlightening to gain opinions... on PARF-n-all... Danke. A hoist to friendship far and wide http://forums.pelicanparts.com/support/smileys/wat6.gif


TY UncleCharlie. PARF!

Technical. Relay #2 is in hand. Tomorrow's agenda = wire it up and see if round 2 goes better than 1st. Is possible I put too much heat on pins when soldering... and fried components. Will do differently this time. Plan is to "bench" system in car. If relay works, will move on to finish install. John suggested a test which I now also have a 2nd step down for---plan being to always keep Arduino's power isolated from power served to relay's coil.

Karl,

Today is a good day, as four elements were officially named AND UNESCO has recognized Belgian beer culture as a treasure of humanity. This one's for you!

^^^ HA! That's impressive! TY for the hoist/one Dru!

Relay #2. Is same as 1st. Comes with (blue) jumper that de-isolates relay’s coil power from Arduino. Will remove jumper and serve 2 isolated power supplies to relay. On signal side goes Arduino power. On coil side am going to test 12v stepped down to 5v 3amp served from car's fuse panel. Ground on both sides is common.

http://forums.pelicanparts.com/uploa...1480719113.jpg


Different approach this time. No soldering/heat.

http://forums.pelicanparts.com/uploa...1480719184.jpg


New step down for 5v test. Intentionally got this so preferred gauge wires can be attached. Using 16 gauge on 12v side. 26 on 5v. Will “bench” in car tomorrow morning.

http://forums.pelicanparts.com/uploa...1480719266.jpg

http://forums.pelicanparts.com/uploa...1480719266.jpg

2nd relay - Not working either. This time heat is not a potential culprit. Power is feeding coil side and I confirmed (via YouTube for this relay) that 5v works this coil. (Last relay 12v was going to coil.) Power is going HIGH and LOW to signal pin---I checked the pin to confirm when: When relay’s LED light is ON, power signal is LOW. When light is OFF, power signal is HIGH. (That seems opposite to me but doesn’t matter at this stage.) What matters is the normally closed side which has continuity to the common… that continuity never changes regardless of the relay signal being HIGH or LOW / light ON or OFF. I tapped on the relay to possibly free a stuck coil contact but that did nothing. I also tested both relay switches (as this is a dual config)---same results for both.

If relay has power to the coil---and it does, and the signal is changing---it is as I measured & confirmed at the signal pin... continuity with the common should change between the relay’s normally closed and normally open terminals. That’s not happening. Fact that both the 1st and 2nd relays are behaving the same… finger’s pointing to human error. What have I got wrong here? There’s power offered to operate the coil and the signal is shifting and no relay magic…

Seems I’ve tested everything but have I?

Electrical expertise is most welcome.

^ I'll have a stab and say that the digital output that is connected to the relay board opto coupler needs its configuration set to 'open drain'.

What happens when you ground IN2?

Discseven,

Few things.

It's pretty typical for these types of relay modules to be active low, meaning the high-current side of the relay conducts when the digital control line input is 0V (low), and doesn't conduct when the control line is 5V (high). The LED indicator lights up when the relay should be in conduction mode, i.e. the input is 0V, which agrees with your observations. You can understand that by looking at a typical schematic, like this one:

http://forums.pelicanparts.com/uploa...1480799796.png

So, reading from the schematic, an input logic low (0V) turns on the indicator LED and simultaneously the LED in the opto-isolator. Under these conditions, the isolated NPN transistor turns on (conducts), which drives the base of Q1, turning it on as well, and conducting current through the low-current side of the relay, which in turn switches it into the conducting position. With an input logic high (5V), the indicator is off, so is the opto-isolator, and so is Q1.

With all that in mind, there are a few potential errors with your hardware/wiring setup. (1) you may need to connect both ground signals or at least confirm that they are connected on the module itself. One is certainly on the optically-isolated side (emitter of Q1), but without a schematic for your module I'm not sure where the other one goes. (2) Are you sure the module can be powered (JD-VCC) off 5V? The datasheet for your relay indicates the coil activation current is 30mA and the coil resistance is 400 ohms. With 5V, you're only driving 12.5mA (max, that ignores the voltage drop across Q1 which in saturation is probably 0.5V or so), which probably isn't enough to activate the relay. THIS IS MOST LIKELY YOUR PROBLEM.

Best, Noah.

Thanks Jonny... When you refer to "the digital output," are you saying that the Arduino's sketch/program needs to specify "open drain?"

Will test grounding IN2 tomorrow morning and post.




Appreciate input Noah... 1) I did confirm the ground on both sides on the 1st relay having continuity. I believe 2nd matching relay does same but will confirm tomorrow. 2) "Sure" as you mention it is questionable. I checked multiple references online and there are indications that 5v works the coil in this particular relay. 12v was also tried in the first relay. Given the variables, I hold we cannot be "sure" until whatever the issue is here is discovered.

Found a fellow on YouTube with same problem concerning relay not triggering. Link below is fellow's 4th vid on subject. When he connects 5v to relay... it switches. He initially thinks it's a current issue.

https://www.youtube.com/watch?v=ozYRj-wuRNs

Same guy, different link... it's a code issue. He's missing: pinMode(1, OUTPUT) But, he's not driving his relay with an Arduino---he's got some other mini-microcontroller. Here's a screen capture of dialogue referring to missing code:

http://forums.pelicanparts.com/uploa...1480812518.jpg

pololu - Why does my microcontroller's 5V out fail to activate my 5V relay? - Electrical Engineering Stack Exchange

Was rushed for dinner so I'll admit to going through entire posted dialogue too quickly. Tomorrow Morning I'll do tests promised.

Thanks to both of you for the input. :)

Karl, was this ^^^ and example of ----> :D

Karl,

I agree that, if everything is wired/powered correctly, just grounding an input should activate the indicator LED and switch the relay. If that works but the uC doesn't, then you probably have a code and or output driver problem. Your setup should work with either an open-drain or push-pull output topology on your Arduino. However, you mentioned that your control signal was switching correctly so I don't think that is your problem.

Your link only makes me more confident that your current setup can't work. The info you provided was using a 5V relay (SRD-05VDC-SL-C). You don't have a 5V relay, you have a 12V one (SRD-12VDC-SL-C). You mentioned your first effort powered the relay off of 12V and that it still didn't work but I can't help troubleshoot your previous setup without more information. I just don't think your current setup can work, and even if it does it will most likely be unreliable as components will be operating well outside their specified parameters.

I think you need this 5V relay module instead of the 12V.

http://forums.pelicanparts.com/uploa...1480855124.jpg

Then you can wire the relays directly to the Arduino.


http://forums.pelicanparts.com/uploa...1480855988.png

Jonny... John also suggested I ground IN2 and see what happens. (John, if you're following along, pardon me that I neglected this.) Will do this today.


HA! Not in this instance Rono. Dinner was genuinely dinner.


I looked at John's code related to driving the relay, there is nothing that appears to indicate pin "output"... or "open drain" as Jonny noted. Before messing with the code, I want to make sure all wiring and voltage is correct. I looked at voltage from the new step down to the coil side of the relay yesterday and it was "around" 5v. Will note exactly what it is today.

In post 76 there's a parts list. As far as I know I've been consistent when referring to the relay as SRD-12VDC-SL-C.



Schwarzy... This relay is to ON/OFF ac's compressor. I believe 12v is obligatory.


After breakfast am diving back into car. Will collect as much data as possible for comprehensive status post later today. Thank you guys for your participation :)

Karl, I believe the 05 vs 12 in the part number refers to the CONTROL side voltage and not the load voltage. The load side rating is written right on the relay body; 10A @ 30V for both the '05' and '12' part versions. If you want to run your relays you will need to provide 12V to the control side of the relay. The NPN transistor in the schematic I showed (Q1) must be able to pull enough current through the relay to active it. For your relays, 5V just isn't enough head voltage to provide adequate current through the ~400 ohm control-side coil. You have two options: (1) switch to the 5V version; SRD-5V-SL-C or (2) wire what you have correctly with 12V available for activating the coil.

Best of luck with your testing, Noah.

School'd! I am reading that incorrectly. Thanks Noah and pardon me Schwarzy. System was first car benched with 12v feeding relay. I stepped it down to 5v to see what would happen.

Continuity:

Between car and relay, everything has continuity. Display is working and all readouts appear appropriate for the day.

Voltage:

12v input side of new step down for 5v service to relay’s coil = 12v (I know now this is meaningless for this application but here it is... for the record)
Output side of step down = 5v
JDVCC / relay’s coil side = 5v via step down connection

Relay has 2 Ground Pins = common ground
Signal light ON, Signal Pin = 0v
Signal light OFF, Signal Pin = 5v
Power Pin on Signal Side = 5v
1st and 2nd relay have matching voltages.

...Sensor Failure:

Yesterday, to be able to “Set Temp” above and below cabin temp (in order to turn system ON/OFF), cabin sensor was cooled with bag of ice. Condensate soaked sensor and it disconnected. System will not work without all sensors connected/working. Figured overnight it would dry and work today... it didn't. (System shows a sensor disconnect/failure by freezing on Porsche logo.) Replacement sensor is ordered.

This does not bode well for the ambient sensor located upside down in left front fender / door jam---straight behind antenna. Question is: will ambient sensor survive driving in rain? I believe failed sensor got soaked. This soaking may be different condition than ambient sensor will ever experience.

Grounding Test: Did not complete due to sending hardware to John.*

On coil (left side) jumper is connected and there’s common ground between left and right sides. On right, power is supplied to 5v pin. Now grounding IN2…
5v to coil side:
Click = ______
12v to coil side:
Click: _____

* John returned from out of town yesterday and got caught up with relay situation. While he benched the system successfully, I recall he checked the signal to the relay---which worked---but not the relay itself. No blame on him---I'd have done same. If signal is there, relay should switch (provided relay is good and wired correctly.)

Bottom line… John requested hardware sent to him and he’ll figure out what's going on. Is on the way. In the meantime, am going to look further into the sensors used for ambient & cabin data.

Uncle Karl, there are some seriously smart, electronics MFs posting here - am vicariously learning a lot from your thread (and having some good laughs, too, buttofcourse :D)!

Other than cockpit sensors, anything outside the vehicle need to be weather proof (sealed).

However, if your occupants have high metabolism rates (they sweat a lot), if you ever intend to wash out the cockpit with a garden hose (like some used car dealerships do),
you spill your coffee often during down shifts, the neighbor's dog sneaks inside the door you left open, you believe the climate guru's are PARF or.... if you live in an area that see's humidity for long periods of time.... 'sealed' units my friend.

^^^ I know you Rono... padded cell with uberairsystem and multicolored dancin-teeners... you're no technoslouch in your own right. (Respect ya.) And CircusCircus too boot! (Your over-da-phone diagnosis lives in infamy Bro. Will consider putting you in my will... when I get to it. My Alodine collection is definitely yours :D )


Stuff I read on DHT21 AM2301 Digital Temp & Humidity Module seemed promising. Knew it would not hold up to direct downpour and so the sheltered location. Given what has been experienced... am looking into DHT sensors further. Also looking---as you suggest---into sealed units. Problem with "sealed" is ability to read humidity. We'll see how sensing pans out.

On completely different topic... believe I heard---possibly from you---that charging AC system is best done on hothot days. Is this true? If so, what's the technical purpose/advantage?

Thanks for the props, Karlicous, and in celebraion of your a/c pimpin project, I present the following (since it's kind of like you are on the a/c stage! :D)! Brand spankin' new material from one of my fav bands.

<iframe width="854" height="480" src="https://www.youtube.com/embed/fBYVlFXsEME" frameborder="0" allowfullscreen></iframe>

I'd be looking at a solid state relay (SSR) myself:

1 Channel SSR Solid State Relay High-low Trigger For Arduino Uno R3 5A 3-32V | eBay

You just have to make sure that the output is DC rated.

http://forums.pelicanparts.com/uploa...1481033721.jpg

On top of the skull&dagger muzak we're so fond of... add puppet profundity. Way to pick em Rono!


Like the idea Schwarzy... thanks for recommend. This will be the way to go if the 2 Songle relays prove faulty. First relay I may have messed up---with heat. Second was treated with kid gloves. John will receive both of them tomorrow. Basis of this project/thread is R&D. Goal is to find problems... solve them... and share the learning curves. Before abandoning Songles, John has op to uncover this Songle mystery and resolve whatever the problem is.

Just got word from John. Neither of the two relay boards are functional. Exactly why requires an autopsy (which is John's call to do or not.) Is enough for me to know they're not working. Priority is to get one that does.

Ordered 5v as backup (after learning of my interpretation error---TY guys) but before Schwarzy's input on solid state. Should arrive in day or so. That unit will go to John for his testing (before I do anything with it.)

Update = John's test new 5v relay... it works with addition of 1 ground wire added to signal side of relay. I screwed up ordering replacement temp/humidity sensor---failed to place order days ago. Just discovered this fact yesterday when getting all parts together. So... will be a few days waiting on missing sensor to arrive.

Since last post, new parts acquired include: 5v relay (replacing 12v), DHT temp & humidity sensor (replacing one I ruined during testing.) Together with new parts, John and I have been sorting through a few issue…

Refinements made:

STEP DOWN & RELAY – 12v relay has been changed to5v. Dedicated power for relay has now been run from fuse panel (cig lighter fuse) to dedicated 12v > 5v step down.

5v relay has same appearance as 12v but for text printed on modules. Compared to 12v relay install, 5v relay now includes a ground added to the VCC side. (Could use single module relay here. Extra module serves as spare / back up.)

http://forums.pelicanparts.com/uploa...1487006090.JPG


TEMP & HUMIDITY SENSORS - Two DHT temp & humidity sensors exist in system---an inside for cabin temp reporting (toArduino and data display screen), serves to compare target Set Temp to Cabin Temp with system cutting compressor OFF when both temps match. System turns compressor back ON after hystersis buffer is achieved. Outside sensor monitors ambient temp and humidity for entertainment only.

Having tested DHTs under various circumstances, there’s doubt as to whether the exterior sensor will continue to operate successfully after a 100% humidity experience. Reviews say these DHTs work through 100% humidity. My experience suggests differently---but then I forced cold & humidity on the DHTs for testing purposes. Perhaps a DHT responds more favorably to “real world” temp & humidity change. Because the exterior unit is wired and Arduino is programmed specifically for the two DHTs… will leave exterior DHT to the test of time. Cabin DHT should experience no issues.

With the first DHT’s failure (due my wetting it,) a new unit has replaced the wetted one. New unit was also subjected to 100% humidity. Humidity data froze at 99% (according to info displayed on the system’s data screen). Sensor was disconnected at housing terminal… humidity sensor wiped off… AC powered OFF… sensor reconnected... then system powered back ON. Sensor then resumed working properly.

http://forums.pelicanparts.com/uploa...1487006160.JPG

DHT sensor’s plastic housing is clamshell with friction fit. It splits in half with force applied at its seam. Wires coming with unit are terminal-attached to a circuit board that’s single-screwed into housing.

http://forums.pelicanparts.com/uploa...1487006194.JPG

Sensor board's bottom:

http://forums.pelicanparts.com/uploa...1487006327.jpg


DATA CABLE FAILURE – During system tests, the Set Temp control knob began working both the Set Temp and Screen Contrast adjustment. John advised there being a wiring issue. Indeed, wires at the data cable’s junction at the AC Control Box were snapping off from the junction. One is snapped here. Other wires were almost to this point.

http://forums.pelicanparts.com/uploa...1487006411.JPG


Stress on wire connections at the junction---due to constant handling of AC Control Box---and so the cable’s repeated pivoting at the junction is to blame. My bad (for not securing cable when it was first installed.)

http://forums.pelicanparts.com/uploa...1487006458.JPG


Old junction's been cut off and new installed (keeping all previous wire positions intact.) Cable’s now secured to AC Box with zip tie (passed through two new holes put in Box.)

http://forums.pelicanparts.com/uploa...1487006513.JPG


Refined system was just bench-tested in car. All data collection & on-screen display is correct, screen contrast control works correctly, new 5v relay is switching compressor power feed ON/OFF correctly.

John---your persistence in dealing with the info-tech / Arduino side of this journey…especially lately given my noted cable engineering shortcoming… much respect & admiration your way!

REMAINING DIGITAL TEST – As mentioned above, is questionable whether or not exterior DHT temp & humidity sensor will hold up to rain of any degree. If DHT sensor fails, will see about modifying it to prevent 100% moisture from reaching sensor.

NEXT STEPS - AC Control Box gets installed in center console. Console gets mounted in cabin. AC system gets evac’d & charged (brought back into operation from Black Death.)

Complexity Renote

Why bother complicating an ‘80 911’s AC system with digital control?

This is a collaborative build-journey to explore new ideas & techniques, resolve issues that arise, and arrive at a working system as a conclusion to the creative challenge accepted at the outset... The main purpose being to gain---and share---new insights. (Complexity is a necessary byproduct here, not a goal.)

Schwarzie... thanks for taking the time to comment/suggest 5v relay and for putting together this wiring diagram. (I'm not IT guy in this build so would be up to John to comment on your wiring plan.)

The reason we are not powering the relay from the Arduino as per Schwarz663 is due to a conversation Karl and I had, earlier in the project where he wanted to isolate the relay from the Arduino. Thus there is a separate 5V power supply to energize the relay, whereas the Arduino activates the control circuit on the relay board. In that fashion both components are separated by an optoisolator in the relay board.

As to the earlier discussions on using 12V vs 5V relays, it is irrelevant. which is used The 12 V and the 5V are the voltages necessary to energize the relay coil. The control circuit on the board used the Arduino signal in either case. The problem Karl had was that both 12V relay board were defective or damaged at some point; thus, nonfunctional.

Good going Karl!

Am back in the saddle after being pulled in various directions since last post.

Recent progress...

Pin rack fault - Pin racks were added to Arduino to allow female plug-in terminal connections. Each pin can be pushed through rack if desired, also if not desired. Got system running and power began fluttering then... OFF completely. Found power pin rack being at fault. Changed rack to more solidly fixed pins.

http://forums.pelicanparts.com/uploa...1498858752.JPG

Faulty pin rack as just removed. Longer pins go into Arduino.

http://forums.pelicanparts.com/uploa...1498858752.JPG


Bench testing system in static car. Ice is used to chill cabin sensor for testing compressor relay ON/OFF. Tilt of display in mount is intentional---is so driver sees black headliner reflected in screen.

http://forums.pelicanparts.com/uploa...1498863623.JPG

Got system going... and relay issues persisted---albeit with relay at least switching now. Were also anomalies with data coming consistently from sensors. Minor mod to wiring and refinement of Arduino sketch/program eliminated problems. System then began operating as planned. Much respect to John for relentless participation. (BTW, John's developing Arduino-based EFI system for his supercharged engine. Will add link here later. LINK: http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/960640-another-aem-efi-conversion.html)

http://forums.pelicanparts.com/uploa...1498858993.JPG

Been driving with system installed in console with console attached solidly to car and AC ON for a few days. Purpose being to see if vibration & road shock will screw things up. Also to confirm consistent data collection & accuracy over various temp ranges. So far so good. Only issue found is "one wire" sensor (is in evap's core) getting lost above 98dF---it rotates between two different temps. Is no concern (since evap won't operate at that temp except to start with at times. Once below 99 there's no prob. Believe this anomaly is sensor limitation but not sure.) The highly reflective bezel does not work optimally. Depending on ambient lighting, it suffers severe reflection at times. Most of time it's good. (Toasty lately... highest cabin temp while driving, both windows open = 114dF. More typically it's in high 90s.)

AC is absent refrigerant at moment. Will evac & charge next week provided digital control requires no more attention.

For newcomers to thread, is relevant to recognize this project was taken on to see if and how an Arduino-based AC controller could be worked into an '80 SC.

Evap Core Temp Minimum & Hysteresis Mod:

AC system's ON and OFF automated compressor control settings (32.1 dF noted above) is now thought to be too conservative. This conclusion is made prior to charging and running AC. Automated compressor ON/OFF has been changed (7.26.18) to:

Minimum evap temp = 29 dF
Hysteresis = 3 dF

Theoretically, intent is to push slightly into evap ice-land and cut compressor OFF before ice builds too much. Hysteresis will then "bleed" off ice accumulation... allowing compressor to come ON @ 32 dF. This should provide lower vent temps than prior settings offered. Curiosity looming is how far below 32 dF can evap cope with---in Miami's humidity---before reaching an ice-block level that renders system useless? With Arduino, can reprogram evap's core temp until optimal functional temp is found.

Been waiting for 90+ dF day---without rain or prior commitments---to vac & charge AC. Almost got whole enchilada a few times. More patience needed for ALL conditions to align.

.

Been waiting for 90+ dF day

Put the car in a garage with a heater.
We have many shops in the west where their
shops are quite warm inside. I guess their landlords
won't allow them to have AC.

^ Can't tell if you're in leg pulling mode or serious. IAC---Point of 90 is to charge and test ambient-to-vent temp delta all in one shot. Couple of times I've got vac going and ambient's at 90+... am thinking AC's gonna get refrig today!... then afternoon monsoon comes and ambient nose dives... then AC progress shuts down. This pattern can't go on for much longer. (August is historically the hottest month in Miami.)