Ok, here we go. I bought my S4 last November so I didn't find out my A/C didn't work til this summer....anyways I've lived with it all summer but now it's getting to be too much, the heat is killing me. The air just won't blow cold.

Here is what the Vag said -

Monday,13,August,2007,16:53:00:32933
VAG-COM Version: Release 704.1
Pace
Address 08: Auto HVAC
Control Module Part Number: 8D0 820 043 Q
Component and/or Version: A4 KLIMAAUTOMAT D58
Software Coding: 00160
Work Shop Code: WSC 06435
4 Faults Found:

00787 - Temperature Sensor in Fresh Air intake duct (G89)
30-10 - Open or Short to Plus - Intermittent
00779 - Outside Air Temp Sensor (G17)
30-00 - Open or Short to Plus
00792 - A/C Pressure Switch (F129)
31-00 - Open or Short to Ground
01206 - Signal for Duration of Ignition Off Time
27-10 - Implausible Signal - Intermittent

I then cleared the codes, ran the engine and A/C for about 10 min and scanned it again - Here is what the Vag shows currently:

Monday,13,August,2007,16:55:16:32933
VAG-COM Version: Release 704.1
Pace
Address 08: Auto HVAC
Control Module Part Number: 8D0 820 043 Q
Component and/or Version: A4 KLIMAAUTOMAT D58
Software Coding: 00160
Work Shop Code: WSC 06435
2 Faults Found:

00779 - Outside Air Temp Sensor (G17)
30-00 - Open or Short to Plus
00792 - A/C Pressure Switch (F129)
31-00 - Open or Short to Ground

I had the car into an A/C shop and the guy there charged the system, and when it still didn't blow cold - he said the compressor was toast (he didn't vag it, I did when I got home), that a possibility? I know this has already been discussed but I can't really get a good answer on where to start. Is my A/C pressure switch toast? Is there a way to test it? I've noticed that my outside temp reading on my dash shows about 10 degrees above what the actual outside temp is, what does it all mean, ha?

Also what is the best way to get to that switch? Pull the headlight out, bumper off, or both??

Whats do you all think? Thanks so much, I've only been using this forum for a few months and have already learned loads - you guys are always super helpful!

- Jason

 

Look the codes up http://www.bentleypublishers.com/tec....dtc.table.htm

It sounds like you have a couple of things disconnected, or just failed parts. Both are in the front bumper area & a PITA to get at. Also check the connections under the plastic cover for the PS fluid, you might find them disconnected there.

With out the pressure switch, the pump will not run.

 

Thanks!

Real quick I noticed that some others on the net get the same error code but instead of "Open or Short to Ground" they get "intermittent". So am I correct in assuming that my pressure switch is either unplugged or completely dead (oh I just re-read your post, you answered that....ha)??

Also, would this code:
0779 - Outside Air Temp Sensor (G17)
30-00 - Open or Short to Plus
Cause the temp reading on my dash to display "---" becuase it does actually display a temp (although its always a touch high)?

Thanks again....wish I would have done all this last weekend when I had the bumper off for a snub mount install!

 

Funny story. Just fixed my A/C last nite, epoxied up a hole a rock left in the condenser. Pulled off the front bumper, took out the condenser, patch, reassemble, charge, took about 4 hours start to finish. Included 2 Hrs cure time for the epoxy with heat gun (hair dryer). Anywhoo the cycling switch is on the rt. side of the condenser, easy to get at with the bumper off. not a bad job to take care of. And like 2K said, without the cycling switch, the compressor will not...cycle. Common problem on almost every 02-03 Trailblazer. Good Luck. Damn, im gabby...

 

Update...

Went to the dealership and got a new pressure switch ($150), installed it, cleared codes, then ran the AC. The same two codes popped up, err!

Decided to check the pressure in the system - of course it was way high, so I evacuated the freon til it was within tolerance and sure enough the vag code dissappeared - wasted 150 bucks???

If excess pressure was creating the issue shouldn't the vag code have mentioned "pressure too high" or something, not just "open or short to ground"???

Well anyway that code is gone just leaving the temp sensor code (g17), but the Air still won't blow cold. Atleast now I can hear the compressor kick on as before it wouldn't.

Questions?

A) Where is the g17 sensor? - Isn't it supposed to be in between the radiator and the bumper attached to the cooling line for the power steering fluid?? I don't think I even have one (I was in an accident a couple months back I'm wondering if they never put it back on)

B) Can the g17 fault code keep the A/C from blowing cold?

C) If the g17 really is missing or broken then why do I get a temp reading on my dash (although it is +/- 15 degrees from accurate)

Thanks guys, I think we're making progess. I'm one step closer to being able to drive my car without getting drenched in sweat!

I just hope the compressor isn't bad after all!

 

Jump B+ to the compressor see if it engages

 

Now that the pressure switch problem is gone I can hear the compressor kick in, but It never gets cold. I did vag the output from the G17 sensor and it shows something like -39 degrees, can this keep it from getting cold even though I'm pretty sure I hear the compressor running??

Thanks!

 

Yea, if the car think's its too cold, it wont let it built pressure, or the lines/ oriface tube could be freezing up, lexus had an issue with that. You did do a pressure check on the system right, its supposed to have 700g in it.

 

Alright well I'm off to get a new sensor, which my insurance co. is paying for, as I was in an accident last winter and the body shop completely forgot to put a new sensor in - I've just got an empty mounting bracket under the bumber and a connecter in the engine bay with nothing plugged into it, lol. I'll let everyone know the outcome. Keep your fingers crossed that the compressor is still good!!!!

 

i ran into the same problem. mine was just a pinched sensor wire behind the front mounting bracket. I got the timing belt changed and when we were putting it back together, we didnt pull it clear enough. its was something so simple luckily i didnt have to spend any money on sensors. i would say just check the wires and make sure they all have current running, but hey atleast your insurance company is paying for the sensor.