Still issues with the AC not blowing cold. But now I can describe as with detail. Any and all help is greatly appreciated.

1st I checked the low side with the vehicle off and having sat all night:



I then started the vehicle and set the controller to OFF. As you can see from the video the ac compressor cycles and and gets wet from condensation:



http://youtu.be/eIf0KS1D5ss

I then moved the controls to recirculate. In this mode the compressor did not cycle on at all. The low side reading remained static:





Then moved to the head feet setting. Again, compressor did not cycle on, reading remained static. in addition by this time teh accumulator was dry as a bone from the condesation a few minutes earlier:







Moved the controller to head only. Compressor began to cycle but NO condensation was present.



http://youtu.be/m08akONDlKk

Changed setting to feet. Again compressor began to cycle but no condensation was present.



http://youtu.be/XvNPnIcH4yk


i also ran the AC check on the head. No codes:

http://youtu.be/QdaGf6StcOE


After all my testing I shut the car off and came back about 20 min later to get a static reading with the car off. This is what i got:




Any ideas on what the issue may be? TIA

1996, right?

Let me get the pages from the FSM tonight for AC diags.

yup, 96 LT4 Collectors

No edit button available so here are the links in the same order as above.

Sorry I am on my phone and don't have time to fully respond....you need a full set of gauges to correctly diagnose a problem. You need to know both low and high pressures when running. Static pressure means very little, it is just a reading of the pressure based on the temperature of the gas as it sits (ambient temp if hasn't been running). You need to compare the running pressures vs a temp/pressure chart for your system.

As a side note, if you can get the compressor to engage that is a good thing and overall indicates the system is capable of functioning properly.

I will have to reread the thread later and post.

I have emailed you the PDF... it'sway too large to upload!

It's about 4 megs, which should email just fine.

Matatk, you in the Plainfield/naperville area?

I can get these from the loaner tool program at Auto Zone:
http://www.autozone.com/autozone/acce ... temIdentifier=290026_0_0_

In addition I own a Klein CL200 amp clamp with temp probes so getting accurate readings will be ok.

Bogus, I did not get an e-mail
sent you a pm

It was too big... sorry... resent it from my normal acct.

Tool in hand

OK, got a chance to sit down and watch the videos.

When you are checking for codes, did you try to scroll through? When you get the "00" that means diagnostic mode. Then you use the up or down button for the fan to go through them.

http://www.corvetteforum.com/articles ... de-translation-1990-1996/

It's good that you got the gauges, but you might not need them yet. From watching your video it seems that the compressor is cycling just fine. I mean in a mechanical sense.

Your problems appear to be coming from the control head itself. Have you done any work recently or replaced the battery? The first thing I would try is disconnecting the battery for a bit to reset everything. Surprisingly that's all it takes on some on the later Vettes with C68.

If that doesn't work, you might consider disassembling the control head and cleaning it well with alcohol:

http://www.corvetteactioncenter.com/f ... -climate-control-r-r.html

http://forums.corvetteforum.com/c4-ge ... ontrol-button-repair.html

Did you ever get the troubleshooting tree from Andy in your email? I don't personally have it. It might use the Tech 1 to bypass the control head to run tests.

Hope this helps.

Matthew

In the diagnostic mode I did scroll through. If you watch the video again you will see that when I enter the mode the screen shows: -00 when I hit the fan auto button the display changes to just : 00 meaning no codes.

As far as the head unit needing to be power cycled. The car was in the garage with a dead battery for several months. It had a new battery installed about 6 weeks ago. The battery was disconnected for a short time about 3 weeks ago so any power cycling should have been complete already.

I'm going to attack the head in the next few minutes.

and finally, no I have not received an e-mail from Andy yet.

I know people are busy so thank you to everyone for helping me out. I'll report back about eh head and do a write up with pics on it as well.

Henderson

I saw that you hit the auto button once you entered the diagnostic mode but I believe you have to use the up or down button to scroll? I don't know since I don't have a 96 but it's worth a shot.

Can't hurt to disconnect to battery first and try one more time. It seems to work on other ac issues I've read about.

damned emails... I sent that last night...

I used the comcast acct you indicated in your PM.... check your spam bin? I sent it with the subject ACDiags from Bogus.

It has a 4mb pdf attached.

Andy can you send it to me so I can look it over?

OK, Andy... I feel like a dumb ass. See your PM's!

The head was pulled and cleaned. Gotta run some errands so reinstall wont be till a little later. Good write up coming on that.

I'm gonna disco the negative battery cable and leave it unhooked while I run the errands that way we can say EVERY possible measure was taken with this!

When I reinstall I will run the diagnostic again this time toggling through b4 hitting the "enter" key

sent to both of you!

it's a touch over 4mgs long.

About 50 pages of AC Trivia.

No luck. Head is clean and still the same issue.

Gonna go back and finish putting it together.

On a side note, I found this short video. Now I understand what you mean when you hit the center button and there were no codes. You can still scroll through and check parameters:

So a thought that just popped into my head. The older C4s with C68 had a problem when the blower fan would run even with the car/ignition turned off. This was caused by a bad blower control module. The BCM receives a constant 12v even with the car off, and when it would go bad internally would short out and run. Check the info Andy gave you and run the diagnostics for the BCM to see if it is bad. The blower control module for your year fits 93-96, GM #16174981 (old) and 12368390 (new), AC Delco 15-71970.

I checked the FSM pages Andy sent but that portion doesn't address the BCM to clutch testing portion. I sent Andy a message to see if that's in the electrical supplement portion.

you both have more mail.

Id this the chart I should be going by when I check the pressure?

If so I assume the first line is the ambient air temp (outside)
2nd line is the high side pressure
thirn line is low side
and fourth is the output of the ac vent




which is the high side connection in the vehicle?

There is another chart in there I would use. You can't interchange the fittings between high and low so it will be obvious. If not, one of the diagrams in the fsm shows the location of the fittings. The low side is on the accumulator and the high side is on the line.

Regardless, your issue lies in the electronic or electrical portion of the ac system.

here are the static readings. car hasn't been on since yesterday and from what I've read the ambient temp isn't critical for this. Based on these readings should I go ahead and return the manifold gauges?

Static pressure not running from ambient temps doesn't really mean anything. Not nearly as important as operating pressures. I don't think you need the gauges at this point. Up to you if you want to hang on to them or return them.

Gonna take it back. At this point no use for it so rather not keep it. Any suggestions on how to pull the programmer?

The static pressure check was more for peace of mind. With the needles both pegged at 50 it's a model for a system properly holding charge. Maybe the pic will help someone else doing an ac search

I sent you another e-mail Andy. Looking for section 8A of the fsm.

Thanks

I wasn't at my computer all night last night... sorry...

I will burn off 8A tonight.

Okay trying to catch up... have not watched the videos yet..


with the 90-up C68 I have had issues int he past where I have not codes, but I also would get no AC either.

Matatk is on the the right track there is a reset procedure for the C68, once done properly the A/C should work.. keep in mind one of the steps on a battery pull/ AC reset is the Blend door must fully complete its recalibrate cycle

essentially what I would do is this:
-Disconnect battery for 5 min
-Reconnect battery
-Turn key to 'ON' (don't start yet)
-wait until the blower fans starts blowing, this will be after a few minutes and once the blend door has calibrated

-once that is done, start car then test your AC


It is hard to determine much form static pressures, once the Compressor cycles then you can check with gauges..

to confirm the Compressor cycles you can jumper a switch/sensor to have it run and make sure the clutch works etc

I think there are 3 sensors/switches or a variation of them in the system, High pressure cutoff, cycle switch and one other.. been a couple years since I really got into it so I would need to look at the FSM again

looked at couple of videos..

Cycling fast typically means low on refrigerant, but if there is a blockage I know there is a High side cut off..

As for the compressor cycling in the off position, it could be a bad Programmer found down by the accelerator pedal.

So:
when completely off does the Compressor cycle? if so, then I doubt it is the A/C Head unit and would lean towards the programmer.. but I don't suggest throwing parts at it yet.

IF time allows I will look at my 96 FSM tonight as well

Quote:

The static ac check was to verify that the system has refrigerant. All the data I read stated that with the vehicle off a properly charged system will have 50psi or greater in the system. So the static check in my opinion at least verifies the system is charged. This car sat for 18 months, if it has 50psi like the book says it's not leaking!

The head was already taken apart and cleaned so that's not the issue.

The battery disconnected but not cycled like you described above.

When you say OFF, do you mean the car being off or the Ac set to the OFF button?

If you mean the CAR OFF, then nothing works.

If you mean the AC OFF Button engaged then in this position YES, the clutch cycles and in only the OFF position do I get the condensation since the clutch is cycling.

odd... I am still leaning towards the programmer...

But a blockage does weird things, and sitting for an extended period could easily cause a blockage... something sits, festers...

Not that this is an exact comparison, but my 1976 AMC Pacer (I know, POS), had a blockage at the top of the dryer/accumulator. It condensed and then froze up there. Nasty, really. If there is a bad dryer or oraface tube... something to consider?

Quote:

When I mean off.. Car running/ AC off, since your answer was YES it cycles with AC off car running, I am leaning towards Programmer as well...

I too am leaning toward the programmer. I e-mailed Andy earlier for some more data. We're gonna figure this one out!!!

I will get it to you as quick as I can... but I do have 6:30 PDT dinner plans, if I have enough time after work and before we have to leave... I will, otherwise, it will be more like 8pm PDT.

No worries, take your time. Gonna take a break from the Vette today. Full plate, working on the firebird, driving the kids around and not to mention my shoulder is killing me, so I'm not about to try and contourt myself under the dash!

I'll post pics of the firebird later

a whole lotta emails sent... 4 to be exact. big pdfs...

Section 8A.

Since you found this was a 95 programmer in the car - did you ever revisit the issue/fix it?