A/C NOT WORKING AFTER REFLASH ON E38. Anyone run into this?

[Allen Vos]

A/C is not working after reflash. After diagnosing, it came down to the PCM not enegrgizing the AC clutch relay.

Did a bit of reading and some guys talk about reflashing the CAL data only to fix this.

I do have my orignal LS3 file so could get the info from that, if thats what needs to happen.

Here is a couple screen shots of my Tune Data from my current file and my stock file if it helps.

You'll notice the numbers in HEX for the System CVN numbers are different.

Stock LS3 tune data.jpg

Current Tune data.jpg

We had some very mild weather so I had a chance to drive the car/tune it and did several logs and flashes over the weekend.

I did notice on one of the tunes the AC was working again.

Now I don't have that specific tune anymore as I just overwrote it with the updated fuel trim data

[Alvin]

You've likely made changes to something that didn't need to be changed. Start putting things back to stock.

[Allen Vos]

You've likely made changes to something that didn't need to be changed. Start putting things back to stock.

Can you elaborate on what might be changed or what to look for instead of jumping to assumptions?

I have already triple checked the tune for that.

[edcmat-l1]

Can you elaborate on what might be changed or what to look for instead of jumping to assumptions?

I have already triple checked the tune for that.

Alvin is speaking from experience. When these controllers start doing wonky shit it's almost always because someone had their nosepickers where they shouldn't be. When a car like this comes into my shop with an oddball problem, I don't go looking for the root cause. I flash it back to stock and start over with just the basic tables. They're almost always "fixed" by undoing what someone else has done.

I've said before in one of your numerous threads, you're going to end up causing yourself problems, not fixing them. You're changing all kinds of stuff that just doesn't need to be changed.

[Allen Vos]

Alvin is speaking from experience. When these controllers start doing wonky shit it's almost always because someone had their nosepickers where they shouldn't be. When a car like this comes into my shop with an oddball problem, I don't go looking for the root cause. I flash it back to stock and start over with just the basic tables. They're almost always "fixed" by undoing what someone else has done.

I've said before in one of your numerous threads, you're going to end up causing yourself problems, not fixing them. You're changing all kinds of stuff that just doesn't need to be changed.

If you hadn't noticed my threads, I have put everything back to stock. I have no issue flashing the stock tune back and doing that.
I just think your assuming my tune is so far out of whack and you or Alvin have no idea its very close to stock with the exception of the necessary tables.

Car runs great by the way, Had it out for a drive. No bucking/ jerking or hiccups.

Now If you could elaborate on what kind of issues I need to be looking for prior to a reflash as opposed to constantly dwelling on what you think people did wrong , that would be great.

[edcmat-l1]

If you hadn't noticed my threads, I have put everything back to stock. I have no issue flashing the stock tune back and doing that.
I just think your assuming my tune is so far out of whack and you or Alvin have no idea its very close to stock with the exception of the necessary tables.

Car runs great by the way, Had it out for a drive. No bucking/ jerking or hiccups.

Now If you could elaborate on what kind of issues I need to be looking for prior to a reflash as opposed to constantly dwelling on what you think people did wrong , that would be great.

There's nothing to elaborate on. As I said, when a weird one comes in I don't go looking for the root cause. Sometimes it's not a single table or change it's a combination of things. I'm not into wasting half my day trying to figure out what someone did or didn't do. It gets flashed back to stock and I start over.

I typically flash everything back to stock if it's been tooned somewhere else anyway. Only way to assure of no problems being carried over.

[Alvin]

Car runs great by the way, Had it out for a drive. No bucking/ jerking or hiccups.

OK but the A/C still doesn't work.

I would put things back to stock. You can do it one by one.. until the problem resolves.



When you ask questions here.. Do you want the answer? Or just what you want to hear?

[GHuggins]

When a cam's involved it's usually misfire or idle imbalance related. Make sure your AC idle tables are stock and kill misfires if it's showing any. Misfires are almost always related to the AC being inoperative. Could even be something under the hood being unplugged or worked loose. I've also seen the CAN system from the wideband cause funky cluster and other comm problems. Just other things to check.

[edcmat-l1]

When a cam's involved it's usually misfire or idle imbalance related. Make sure your AC idle tables are stock and kill misfires if it's showing any. Misfires are almost always related to the AC being inoperative. Could even be something under the hood being unplugged or worked loose. I've also seen the CAN system from the wideband cause funky cluster and other comm problems. Just other things to check.

I agree it could be a misfire detection issue, but it should take a period of time, if it is due to that. In other words, you flash the vehicle, it resets everything, the AC should engage and work fine for a period of time, albeit short, before it disables. And, if everything is stock, it should also set a code, at least a pending.

If he's flashing it and the AC does not work immediately after the flash, like too soon for it to know it has misfires, that's completely different.

[GHuggins]

I agree it could be a misfire detection issue, but it should take a period of time, if it is due to that. In other words, you flash the vehicle, it resets everything, the AC should engage and work fine for a period of time, albeit short, before it disables. And, if everything is stock, it should also set a code, at least a pending.

If he's flashing it and the AC does not work immediately after the flash, like too soon for it to know it has misfires, that's completely different.

I don't deny that, but some of these OS's can be touchy. I've seen near dead misses on first fire up kill AC and not set a code. Although I don't know of much other than background items that will cause the AC to not just work because of flashing. It could simply be his ambient resetting at a high temp killing it. OP, did you try cycling it off and back on to see if it went back to working? Lots of temperatures, even some using an actual sensor will max out for whatever reason for a period of time or until driven in regards to actual sensor readings maxing like the calculated ones do. Just depends on the year and OS.

I would also think just changing idle speed, min air, injection timing, VE and MAF wouldn't cause this as I know from his last post was all that was changed. Unless something was changed to affect just AC since then?

[Allen Vos]

OK but the A/C still doesn't work.

I would put things back to stock. You can do it one by one.. until the problem resolves.



When you ask questions here.. Do you want the answer? Or just what you want to hear?

What I would like is someone to help that doesn't just jump to conclusions based on my previous posts. Someone who try's to help and isn't a smart ass.

[Allen Vos]

I don't deny that, but some of these OS's can be touchy. I've seen near dead misses on first fire up kill AC and not set a code. Although I don't know of much other than background items that will cause the AC to not just work because of flashing. It could simply be his ambient resetting at a high temp killing it. OP, did you try cycling it off and back on to see if it went back to working? Lots of temperatures, even some using an actual sensor will max out for whatever reason for a period of time or until driven in regards to actual sensor readings maxing like the calculated ones do. Just depends on the year and OS.

I would also think just changing idle speed, min air, injection timing, VE and MAF wouldn't cause this as I know from his last post was all that was changed. Unless something was changed to affect just AC since then?

Thank you for your input Greg, I did check the basics including wiring right back to the PCM. I was able to ground the wire coming from the PCM to the AC relay and activate the clutch to verify the integrity of the clutch circuit.

I was able to grab a set of AC gauges from work and our snap on Zuess scan tool to get to the bottom of this

I hooked up the gauges and manually cycled the ac clutch to activate the compressor and seen the high side hit 200 PSI and low side around 40 psi, so I at least know the system is not empty. lol

I did a quick system scan with the Zuess and found a "Lost communication with PCM" code in the HVAC module.

I'm assuming this was due to an issue with flashing the PCM with HP Tuners?

Anyways I did a global reset on everything and now the AC is working.

Have any of you guys ever run into something like this?

BTW misfires are turned off and the AC Min airflow tables are stock.

[GHuggins]

To set loss of comm codes while flashing? Yes every time. Something hpt never got sorted out were OE comm/diagnostic protocols. Although I've never seen that kill AC for good like that???? Usually it'll start back with the next ignition cycle. Try clearing codes after flashing with hpt and see if that has any affect - I imagine it won't since it won't comm with the hvac, but worth a shot. Also might want to load check your battery and check connections there just to make sure batt voltage isn't dropping too low.

[Allen Vos]

To set loss of comm codes while flashing? Yes every time. Something hpt never got sorted out were OE comm/diagnostic protocols. Although I've never seen that kill AC for good like that???? Usually it'll start back with the next ignition cycle. Try clearing codes after flashing with hpt and see if that has any affect - I imagine it won't since it won't comm with the hvac, but worth a shot. Also might want to load check your battery and check connections there just to make sure batt voltage isn't dropping too low.

I seem to get all the stupid issues with this car. lol

I always flash with a battery charger on the car. Its something we always did at the dealership I worked at when doing PCM and TCM flashes. Watched a guy brick a PCM not having enough battery voltage.

Batt is good too. Its only 2 years old but it passes a load test with flying colors.

I haven't messed with the HP Tuners VCM Scanner much but doesn't it only get into the PCM and TCM(if applicable)?

Does the HP Tuners interface get into every module on the car, like HVAC, BCM, airbag, ETC?

I figured I would just snag the Zuess from work to help me with that.

The car is an 09 Vette Convertible 6 speed manual

[Guy With A Chevy]

I have to ask for advertising purposes if the belt for the A/C is still present? I have done worse.

And unfortunately no, hptuners only gives us access to the ECM's and TCM's. Reprogramming the bcm that controls the hvac and what not requires gm's special juice

[GHuggins]

I seem to get all the stupid issues with this car. lol

I always flash with a battery charger on the car. Its something we always did at the dealership I worked at when doing PCM and TCM flashes. Watched a guy brick a PCM not having enough battery voltage.

Batt is good too. Its only 2 years old but it passes a load test with flying colors.

I haven't messed with the HP Tuners VCM Scanner much but doesn't it only get into the PCM and TCM(if applicable)?

Does the HP Tuners interface get into every module on the car, like HVAC, BCM, airbag, ETC?

I figured I would just snag the Zuess from work to help me with that.

The car is an 09 Vette Convertible 6 speed manual

Well the only time I've ever experienced this problem personally was with a vette. Don't remember the year it was, but it makes sense. I honestly only even remembered it after you mentioned having to clear the codes for it in the hvac module. Literally have only run into it that one time for permanently killing the AC. Probably some oddball OS.

Otherwise yes, normally when a gm flash device is used it will clear ALL codes and not just the pcm's. Hpt on the other hand won't clear or read the tcm codes, which seems stupid to me, but whatever.

I also don't recommend using a regular battery charger. The sine wave can screw with things. You should be OK since that's how you've been doing it, but keep that in mind. That's why you should have that stupid flash specific battery maintainer in the dealership just for that.

[Allen Vos]

Well the only time I've ever experienced this problem personally was with a vette. Don't remember the year it was, but it makes sense. I honestly only even remembered it after you mentioned having to clear the codes for it in the hvac module. Literally have only run into it that one time for permanently killing the AC. Probably some oddball OS.

Otherwise yes, normally when a gm flash device is used it will clear ALL codes and not just the pcm's. Hpt on the other hand won't clear or read the tcm codes, which seems stupid to me, but whatever.

I also don't recommend using a regular battery charger. The sine wave can screw with things. You should be OK since that's how you've been doing it, but keep that in mind. That's why you should have that stupid flash specific battery maintainer in the dealership just for that.

Fn Vettes eh? They always have some kind of issue lol

I cant remember the brand but its a small smart charger that only charges at around 8-10 amps. I use it most for relearn procedures on cars with the scan tool.