Wondering if any one else has had this problem and what they did to fix it. When I push the button to turn the A/C the light comes on but when I let go of the button the light goes out. Can not get the A/C to work at all. Can that switch be replaced or do you have to have the whole cluster replaced. Here in Florida we need our A/C

 

Check for freon. The system will not function if not charged.

 

Thank you I will have it checked

 

YEP!! Does it BLINK then goes off or just goes out??

Have you read and posted your DTCs using the internal code reader??

BC

 

When you push the button the light comes on and then when you let go it goes out. Not sure what you mean by the DTCs internal code reader... is that done through the DIC

 

This is how...

 

READING YOUR Engine Diagnostic Codes







The Diagnostic Display Mode is entered with the following procedure:



1) Turn on the ignition but don't start the engine. NOTE! You can read the DTCs with the engine running and or driving down the road but it can distract you. BE careful! Some DTCs clear themselves when you turn the ignition OFF!



2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open ect)

3) Press and hold OPTIONS

4) While holding OPTIONS, press FUEL four times within a 10-second period.





Initially, on-board diagnostics go into an Automatic Mode which shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each. ( i.e. PCM = 4 codes) If none are present in a given module, you will see No More Codes on the display.

There are two kinds of diagnostic codes, Current and History designated with a letter suffix, “C” or “H”. A current C code indicates a malfunction is present and active in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes.

More likely it's an indication of an intermittent malfunction.

Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.

Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except English/Metric (E/M). Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present; press GAGES to go forward or FUEL to go back.

To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press and hold the RESET button To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.

NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles.

Once you have the codes, the next question is: What to do with the information?

First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5. You can GOOGLE the DTC and also find information on it.









Here is very good site that explains the DTCs:





http://www.corvette-web-central.com/C5DTCcode.html





http://www.obd-codes.com/trouble_cod...d-ii-codes.php







Make sure to include the H or C suffix!!

 

OK got all that and did the DTC's check and ran a check with my code reader and pretty much things are the same. Now my question is where the heck is the A/C relay
P1545H & P1546H

 

Engine compartment fuse box.Relay located in #34 position.

 

Well I have done everything that was suggested so far and I just got it back from the shop for a recharge of the A/C, replaced the Relay, did the recalibration of the A/C door flows AND still no good. The shop said my problems are somewhere else. The only thing I can think of now is take the A/C control panel out and send it in for repair or replace. You know I really like this car but GM sure SCREWED up in changing everything they did for the C5. Do not know about the C4 but the C5 is nothing but a electrical, computerized headache and disaster. More and more I wish I had my 69 back,, NO COMPUTER

 

Don't know of your mechanical "skills" but first check fuse 24 which is your AC fuse...if fuse is good remove the relay that was replaced...see if 2 terminals of the relay are powered with key ON....one side of the relay is the "load" side which powers the AC clutch and the control side (coil side of the relay) which gets its GROUND from the PCM to energize the coil closed. The ground for the load side is that infamous ground behind the R/H headlight. Now you can take a jumper wire and jump pins 87 and 30 of the relay and see if the AC now works...you have now taken the control side completely out of the picture !!...I was referencing my 01 wiring but your 97 should be the same...I will check specifically the '97 wiring when I get home from work (the place that babysits me for 8 hours and then pays me...LOL !!!)....also the PCM looks at some inputs before deciding whether or not to let the AC operate...one being your ambient air temp sensor...it's that sensor that lets you know how hot is outside....if bad and the sensor tells the engine computer it's COLD outside...like freezing the AC won't work...now the engine computer will not ground that control side of the relay !!...oh, if you can wait a year or two I'll be retiring down your way...Fort Myers !!

 

Thanks for all the info. Not real smart of on this relay and electrical stuff but I will try. I have a set of GM repair manuals coming so hopefully they will help me thru a lot of this.

 

Well after doing all that has been suggested on the forum, the A/C still does not come on. When you push the button the light comes on and when you let go of button the light goes. I am thinking it is time to take the A/C control unit and send in to fix or replace. Does anyone else have any ideas. Thanks for all.

 

I'd give it about a 3% chance it's the AC head unit. Simply no. My cursory reading here tells me you've done really quite little in the way of diagnosis. The AC system is pretty simple really, but you're getting all worked up and blaming the C5 electronics. While I'll admit, there are times the c5 electrical can be a pain, for the most part it's a huge blessing. One hell of a lot easier than fixing the ac on your 69 you pine for, that's for sure.

The codes are telling you to look at the clutch, but so far, I see no mention of you doing that. There's 2 errors that you've disclosed to us and both of them narrow this problem down to the clutch on the compressor. You've also not told us how the system got recharged if the compressor wasn't working. I'd be curious to hear about that. Did you pay for an AC service you didn't get? They put gauges on, said yep, it's full, and took your money? Good questions. How much do you trust this shop?

So, can it still be electrical or a ground? Yes. But it's the compressor that's not turning on (from what I"m reading above). There's a feedback circuit (line the PCM looks at to see if the compressor is running), and both that and the compressor control circuit are telling the PCM to stop the AC, something is wrong. The head unit is doing precisely what it has been told to do.

• DTC P1545 Air Conditioning (A/C) Clutch Relay Control Circuit
• DTC P1546 Air Conditioning (A/C) Clutch Feedback Circuit Low Voltage

Ok, so how about doing as C5Diag above says and attempt to bypass that circuit and see if the AC works. Then track down the wiring issue at the compressor/clutch... Ground, power, or otherwise. Grab your DMM and get checking!

 

OK Mr. K-Spaz I agree with some of what you say and as for my 69 I pine for it was al true muscle NO A/C to take away any power. As far as being recharge the shop did not charge me anything because he did say it took very little ??????.

I also admit that I am not the most brightest person when I comes to checking all this electronic stuff out, so I ask you if I was to plug the a/c head unit back in and have someone hold the button and me stand out and see if the clutch engages, and if it does then tell them to let go of button and see if the clutch disengages. As far as grounds I have gone all over and thru the car and all the grounds have been cleaned and redone, unless there are grounds just for the a/c I do not know about. I do thank you for all you advise and hope there is a way you can tell me or send me to be able to check this head unit out with out sending it in. A replacement or repair is $295 and for that kind of money, if I knew how to check the car itself I could do a lot because time is nothing to me. Thank you again and I must say you do have a way with words.

 

No, that's not what was suggested. Troubleshooting is a process that requires carefully following directions. You've received very good advice, but it is worthless, unless you follow it step by step AND report results for every step.

I'm not saying it's your case, but usually when people use blanket statements to the tune of "tried everything, but no change", it's just out of frustration and not a guarantee that steps were followed. More importantly, feedback info is omitted and it's difficult to proceed.

As suggested below, remove the relay and jump pins 87 and 30 on the socket, observe what happens and report back

 

Something smells fishy here. Let's say you actually took this to a real HV AC technician. A mechanic who supposed to know something about AC. He should have seen plain as day that the compressor clutch did not engage . You cannot add refrigerant unless that is working and at that point there's just no reason to go farther.

As I think about some of the stuff you've said here and what I can surmise from that, I really can't say for sure if there's refrigerant in your system or not. As I think about it it's possible it could be empty. I think that's probably unlikely but I really can't rule it out.

you don't need a second person. You can hear the clutch engage and disengage with no trouble at all. It will be more noticeable if you open the windows and the hood but you probably already have them open when you've been checking now. The sound of the clutch engaging and the compressor running is a pretty noticeable thing so just listen for it oh, it's pretty hard to miss. Listen to it on another car if you have doubt. They all pretty much sound the same.

I really don't think you have a head unit problem. For some reason or other your clutch is not being told to turn on or it is not turning on when it is told to. Really your best bet is just to pull that AC relay and jump across that and see if your compressor clutch engages and starts Cooling. Until you try that, we are handcuffed here trying to help.

 

If you’re not sure these are the 2 terminals you have to jump to see if the clutch will engage...with key on you will hear it click !!...I would also swap the relay with your horn relay first to see if it may be a bad relay that is causing your concern !!...good luck !!...if you want to get your HVAC sent out for repair that is your prerogative !!!...GOOD LUCK !!...and for FWIW I’d take my 01 over a 69 anything as far as diagnostics go....OH the power of a scan tool !!

 

Well I made the jump wire and plugged it in and turned the key on and the A/C light came on and stayed on. Every thing on the head unit worked just like it is suppose to, but it was NOT blowing cold air. I can not honestly say I heard the clutch engage when I turned the key on, but my hearing is not the best.

C5 Diag, you said the infamous ground wire was on the right side behind the head light. Every one takes this different. Do you mean R as sitting in the car or standing in front. I personally say R is from sitting in the car. That being said I took that ground off the stud cleaned it very good and put it back and checked and there is a good ground. I did not and do not know how to check all the wires in that black so called plug, also that being said with the grounds disconnected from the stud and hooked to nothing I turned the key on and the A/C light in the control head came on and stayed on, car running and so cold air and a short while later I heard a loud pop and steam like coming from under the car and green liquid on the floor. I did find a black plastic plug laying there too. I and thinking now it really needs a charge or do you think I screwed something up.


sorry if this is the second post of the same, I got called away and do not remember if I posted so I did

 

Hi !!
Yes, R/H is from the drivers seat...all even numbered grounds are on the R/H side and odd numbered on the L/H side...low numbers towards the front and high towards the back !!...the green fluid is antifreeze and not some aliens blood so you're safe...LOL !!!....don't know about this plug...maybe you can post it...I guess now you will have to locate this coolant leak and take the car to a reputable shop to have them check your refrigerant....you can explain your situation...you said it was blowing cold so it may be OK...you may have a bad AC pressure sensor....that testing may be challenging...you will just have to concentrate on the control side of the circuit...you said you replaced the relay but I would check to see if you have 12 volts on pin 86 key ON which is the control feed wire...from the drivers seat it would be the inboard front terminal (next to the blue 15 Amp fuse) !!...with a Tech 2 or any bi directional scan tool makes this diagnosis a lot easier !!