Air Conditioning via OBD? (ELM327)

**Ironicster** · 08-26-2009, 05:29 PM

I was looking for a cheaper alternative to professional OBD scanners, that allows among others, to read Air Conditioning status, and body sensors. I already have a ELM327 but am willing to buy other cables if necessary.

This would be for use in a car electrical\ Air Conditioning repair shop

Any suggestions?

Tks

**SjLucky** · 08-26-2009, 05:47 PM

more info..?

I wasnt aware of any car that could do that... maybe a BMW or something like that but the rest of them I think, now this is just coming from someone in HVAC (I work in a supply house for res/comm hvac), The inner workings of ac really isnt that complex so I doubt its ran through the ECM/ECC/EMC (whatever its called these days) Your best bet for this is to....

SEARCH, I know surprising uh? It has been covered before. Just as an overview of what I read, one would have to tap into the controls, run them to a fusion brain, then go from there.

**Ironicster** · 08-26-2009, 05:51 PM

i did a search but didn´t find anything conclusive.

we had a professional scanner that could ready many variables and error codes related to A\c system, via the OBD plug. But that scanner as gone bust. We have used obd via pc to read general engine trouble codes, and are wondering if there is sofware that also reads the above refered data

**p2psmurf** · 08-27-2009, 02:29 AM

Not likely that you can read A/C systems with an ELM327 with the exception of USA Cars with a J1850 bus. But then you need more software than standard OBD2.
In most European cars like BMW the A/C is not connected to a standard pin, but to some other pin which varies per manufacturer.
Is this for your own car or are you a professional user?
Which makes do you want to be able to read?

**SjLucky** · 08-27-2009, 12:04 PM

Ok Im a jackass and cant read. MasterCool makes a meter that plugs in to control boards for standard hvac. I'll call my sales rep and see if he knows of anything. If thats a bust, then... I really dont know what to tell you. Only thing I can come up with off the top of my head would be a fusion brain with temp sensors for your superheat and subcool. Now if they had a pressure sensor for your vapor and liquid line that would be helpful. But all of this will be a pain to set up.

I'll edit this post if I hear anything good from the rep.

Havent called yet... I went through my catalogs and I found a couple choices. Mastercool does make one and it seems like the best bet even though it doesnt connect to the board.
http://www.mastercool.com/pages/99134.html
I know this isnt all that you were wanting, I just remembered seeing this manifold when I was ordering a set of digis for a customer. I can order it and have it shipped to your shop with no problems.Hit me up, if this work. 601-482-2617 is the shop number. Or if you have a hvac supply house around they can order just as well as I can.

**Ironicster** · 08-27-2009, 08:02 PM

this would be for use in a elecrical and A\C car repair shop, so the more brands it could read the better(mostly european).

we already have something scimilar to what you recommended, but like you said it takes a bit to setup, so we were looking for something that could give us a diagnostic on A\C, as well as other systems that aren´t OBD standart in a few seconds.

to p2psmurf: so, even if we can find software that can read A\C codes on european brands, the ELM327 wont allow for it?(i´m assuming that if that is the case, it´s because the ELM327 only reads the standart OBD pins...)

tks for your help

**p2psmurf** · 08-28-2009, 02:46 AM

Correct. With the exception of USA cars (GM, FORD, etc.) which use a J1850 bus. On those vehicles there's a good chance the A/C is on the standard pin.
For BMW the A/C is on pin 8, not 7.
When the vehicle has Can-bus, the A/C is NOT on the high-speed bus supported by the Elm-interface. It's on the mid-speed or low-speed can-bus which can be connected anywhere in the diagnostic socket.
There are some good affordable programs for a couple of makes.
For VW/Audi/Skoda/Seat and the Ford Galaxy use VCDS (Used to be called Vag-com). www.ross-tech.com
For Opel/Vauxhall use Op-com. Will work on some Saab's too. http://www.vezerdiagnosztika.hu/index_en.html
For Bmw use the bavarian Technic: http://www.bavariantechnic.com/
For Porsche use durametric: http://www.durametric.com

**DavidL** · 08-30-2009, 12:29 AM

Most newer vehicles with ATC (Automatic Temp Control) the ATC is on the vehicle bus and therefore is available to a good scan tool. The issue is that the protocol is not part of "OBD2" legislation so it's up to the OEM to release the PIDs and transform formulas to interpret the data. It is also vehicle platform specific so it is very difficult for a scan tool company to support every vehicle's details.