This has been a on going problem for me and hopefully finally thanks to C5 Tech with all his help and willingness to solve others problems he feels that my problem is not the A/C Compressor or clutch. I had my car to his hours and for about 2/3 hours he did a lot of checking. One of the reasons was when I got to his hours the darn thing would not quit working, and we needed it to quit. Like they say can not fix it if it is not broke. Well it finally cooperated with us and quit. With his expertise and his knowledge and willingness to crawl under my car he pretty much figured out that it was the ECM. I had power from the fuse box to the condenser but not from the ECM to the fuse box, and by power I mean it had to ground out in the ECM to finish the circuit. I have had it set up for my garage to do a diagnostic test on it in about 3 weeks and I used C5 as my second opinion and he does agree with this. Thanks again there good buddy for all the help, your knowledge and expertise in diagnostic help.

Now I am going to look for a ECM for my 1997 C5. Probably not available new but maybe refurbished, rebuilt. So if anyone knows of a place for me to get in touch with I would appreciate and and all recommendations. .

 

Sorry man. I’m trying to help, but i really don’t understand what’s going on here. This post is really
confusing.

 

I’ll explain it so you can understand it since I looked at the car this morning...customer complaint is AC light does not illuminate after vehicle has been driven for an extended period of time...AC works normally and blows cold air until the car is driven for about an hour..
your thoughts and your diagnostic process to resolve this issue ????

 

Were you not able to diagnose the issue?

 

I did but would like another’s diagnostic process to verify I didn’t miss something !!

 

He is asking you your thoughts, I'm sure he knows why

 

Oh. Awesome. The car is still in your garage? I’m happy to help.

 

No it’s not in my garage right now but like to hear your thoughts !!

 

 

sorry. Don’t understand. What does this mean? He said the car isn’t in his garage anymore. Is there something I can help you with?

 

Weird thread....

is this auto or manual? Slightly different wiring auto and manual...

Here’s my thoughts.... I wouldn’t spend any $$$ until I know for a fact the PCM is the issue.

is it mechanical, wiring, or control issues?

I would get a baseline refrigerant pressure before and after... this will determine bad sensor, wiring, compressor or system issue. Data logger might help with conflicting values...

I would inspect wiring from HVAC to PCM and compressor circuit for AC on and AC request... data line/star connector #1 comes to mind...

 

it is a weird thread. Haha. Politics has taken over this forum. I’ve been a member since 2002 and had my account deleted because I disagreed with “Evil Twin.” This forum protects their paying customers no matter the bad reviews. Real reviews should take precedent over paid reviews. Unfortunately, that’s not how business works. This forum will bury, delete and ban people that try and voice an opinion contrary to the mainstream. At the end of the say, this forum is out to make money and they dont care about your opinions. I know. I know. I’ll be banned in 3.....2.......but I’ll be back.

 

This is an auto...this issue only happens after a long drive so it’s not a refrigerant charging issue...AC temp is good...in this case high heat equals high resistance which equals low or no current flow... all of the AC inputs were checked...ECT, RPM, AC pressure sensor, ambient temp sensor...couldn’t think of any more...load side of relay is good when 87 and 30 are jumped and clutch engages...AC light will stay on in this case...pin 85 (the control side ground of the relay which is controlled by PCM) not illuminating when AC turned on for a few seconds (test light connected to battery positive)...thinking maybe bad connection inside fuse box ??...went to the PCM pin 39 which is the control side ground and still no good...maybe bad PCM...I did not not remove the PCM connector and check for corrosion and pin fitment and will have to do that...OP will be taking the car to his own shop so I said don’t let know I said it may be a bad PCM...don’t like calling a bad PCM without another set of eyes...will probably look at the car again and recheck everything if it’s still acting up...hate AC issues especially when they are intermittent.

 

Ok...the pcm will activate the ac clutch relay when the PCM detects that ac has been requested (ac req) from Hvac unit... it could be hvac controller/ wiring...

 

Well you can take my word for it robmiz, I will not be spending any $$ until I find out for sure that this is my problem, but I do agree when you read it I tried to explain what was going on and probably did not come out right but what C5 Diag said is what is going on. FRUSTRATING but thanks for all the comments.

 

No problems... just trying to help... the weird part I was referring to was the bantering.

There was no mentioned of dtc codes... was there any? I figured C5 Diag did a thorough inspection and looked at them already.

 

No powertrain DTC’s but I believe there were a few history DTC’s in the HVAC module.

 

When you jumped the pcm grounding circuit and supplied voltage to the comp clutch it should have tripped P1539. P1539 is PCM detects voltage to the clutch when the AC request was not given...

You did cleared the codes afterwards... the shop may use this in their troubleshooting... which would be incorrect...

I would see what codes are there...then clear them...