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Have to jump ground to relay to make it

 
Old 07-08-2019, 03:40 PM
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radar502
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Default Have to jump ground to relay to make it

93 Corvette I have to jump ground to A/C relay to make the compressor come on . The switch that goes to ground not working ??? All new a/c parts right amount of R134A . Fans work the doors work just not the compressor unless I jump a ground to the NEW A/C relay .. Any help .. Thanks
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Old 07-09-2019, 06:46 AM
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Deepa
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Disconnect the battery for a few minutes. Reconnect and try normally with everything hooked up as it should be.

The c68 climate controls need to be reset once a code is stored.
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Old 07-09-2019, 07:53 AM
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Originally Posted by Deepa View Post
Disconnect the battery for a few minutes. Reconnect and try normally with everything hooked up as it should be.

The c68 climate controls need to be reset once a code is stored.
Yep tried that nothing ,tried all the setting nothing . The only thing that works is just I touch the ground wire on the relay and bam the clutch kits in ,something not letting it go to ground .. The A/C works if I keep the ground wire touching the ground on the relay . I seen in the shop manual that the black wire going the Compressor is just a ground so ran a ground to it no help . I don't see any other ground in the system just the black wire going the compressor .. Looks like the ground ( the black wire ) grounds the relay as well . I jumped a ground to it no help ..????? It looks like all I need is a ground . But I don't know were its coming from ..
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Old 07-09-2019, 08:22 AM
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What code is the A/C panel showing?
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Old 07-09-2019, 09:58 AM
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NO codes 00 . If I had a code I could fix the problem, maybe . I got nothing ..
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Old 07-09-2019, 10:21 AM
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Are you using the FSM for diagnostics and diagnostic tree? see 8A-67-1 and that vicinity. What terminal of the relay are you grounding for operation? Pin 86 GRN/WHT?
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Old 07-09-2019, 10:36 AM
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Yes GRN/WHT and all I have is a shop manual and have checked all the out side switches I know about all looks good .. Went to a very good A/C shop and he said all outside switches seem to be good ,but he did not have the time to start digging into it .. He jumped the ground to the Green and white wire worked ,R134a is good all new parts ???
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Old 07-09-2019, 10:52 AM
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Originally Posted by radar502 View Post
Yes GRN/WHT and all I have is a shop manual and have checked all the out side switches I know about all looks good .. Went to a very good A/C shop and he said all outside switches seem to be good ,but he did not have the time to start digging into it .. He jumped the ground to the Green and white wire worked ,R134a is good all new parts ???
GRN/WHT is grounded/commanded through ECM but how the programmer relates to all of this ? but you mention NO CODES - SO see 8A-67-5 & 6. Can you borrow a Tech1 from anyone? The first basics mention checking G109 ground and a few others.
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Old 07-09-2019, 12:29 PM
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Thanks. I will check it all out.
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Old 07-09-2019, 01:34 PM
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I am sure what I got , is the Ecm is not sending the ground single to the relay or is it the A/C controller not sending to Ecm ???? Anybody know how to find out , will a Tech 1 do that ?? its took awhile but have it narrowed down to Controller or ECM.. NO SINGLE ..
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Old 07-10-2019, 09:06 AM
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Originally Posted by radar502 View Post
I am sure what I got , is the Ecm is not sending the ground single to the relay or is it the A/C controller not sending to Ecm ???? Anybody know how to find out , will a Tech 1 do that ?? its took awhile but have it narrowed down to Controller or ECM.. NO SINGLE ..
With a Tech1 you could command AC. If you checked the FSM diagnostics for NO AC Clutch it would have sent you to the CHART C10 in the 6E section.There's also DTC for ECM -AC CLUTCH and switching.

See 6E3-C10-4 for start.

These DTC are all AC - ECM related DTC 66, 67, 68 & 69. DTC 68 & DTC 69 seem to be of interest. 6E3-A-102 thru 6E3-A-105
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Old 07-10-2019, 09:24 AM
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Thanks. I don't have a Tech 1 sounds like I need one . I am trying to find someone in Houston that has one, sure would make it a easier to find the problem . Thanks I will look at the manual ,one more time.
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Old 07-10-2019, 10:58 AM
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Originally Posted by radar502 View Post
Thanks. I don't have a Tech 1 sounds like I need one . I am trying to find someone in Houston that has one, sure would make it a easier to find the problem . Thanks I will look at the manual ,one more time.
If you've got a functioning DIC & CCM you should be able to do ECM DTC etc through and using the DIC. See the 8D section of your FSM if you're not familiar with the use of the DIC and IP LCD for diagnostics. I'd think basic diagnostics using the 8D section & the DIC should get you sufficient info.

This might be an interesting read having a later C4

https://tech.corvettecentral.com/201...trouble-codes/

Last edited by WVZR-1; 07-10-2019 at 11:02 AM.
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Old 07-10-2019, 11:42 AM
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Originally Posted by WVZR-1 View Post
If you've got a functioning DIC & CCM you should be able to do ECM DTC etc through and using the DIC. See the 8D section of your FSM if you're not familiar with the use of the DIC and IP LCD for diagnostics. I'd think basic diagnostics using the 8D section & the DIC should get you sufficient info.

This might be an interesting read having a later C4

https://tech.corvettecentral.com/201...trouble-codes/
Thanks , I will do that . I found a shop here in Houston that has a Tech 1 and they act like they know how to use it ,might be a easy way to find out the problem . Well I did something dump not to far back ( MY BAD ) I replaced the steering column cluster ECT . well when I was putting back the knee boaster I could not figure how to reinstall the plug for the OBD-1 so just left it inside ,NOT GOOD so I have to take out the boaster to get to it and after it replaced the column something moved and the boaster did not want to line up .why ????? Bitch to reinstall so I have been just putting it off to remove it .O-WELL going in . I am going to run a code check if I can't figure it out going to the shop .. He has an 93 and said he feels my pain .. and went on the say can be a bear to figure out what is going on with the 93 A/C but has a guy , that's right the guy .. I ran a check on everything under the hood all is good , $1300.00 and counting ,but does work very good with the jumper on it ,ice cold but can't keep that on there , after awhile the A/C system will do something bad ,I'm thinking . Will keep you updated .. I will have cold air well I have colds air but not working just right .. Being 6'1' and 250 LBS not easy getting under the dash .. This time the damn plug WILL be in the right place .

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Old 07-10-2019, 10:47 PM
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Lots of items and things have to happen to turn the compressor on.
The ECM is the ground return for the compressor relay. So all the inputs to the ECM have to be there the for it to energize the relay.

The cycling switch has to be closed.
The pressure switch sensor on the high side line has to be operational and put out a voltage.
The A/C control head has to put out an A/C request (5 volts) to the ECM

These basic items are required in addition to the control head and ECM working properly.
Having electrical diagrams, meters and a knowledge of electronic will help.

The most simplest items to check is the cycling switch. See if it checks closed.

Hard to say where to start. Biggest problem is getting to points to measure and check.
Sorry to say you're probably not going to fix this checking for codes. But you can check just to see if there is a pressure sensor code.

Check all ECM fuses.
A tech 1 can energize the compressor clutch. But I donít know if it will or won't in your case. And if it does not energize the clutch you still donít know any more than you did initially, it's not a crystal ball.
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Old 07-10-2019, 11:42 PM
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Your right lots of stuff has to happen for the compressor to work . I have two switches to install tomorrow ,might help ( High and low ). The tech -1 something might jump out ,never know ..I might have to go down the list till it works . I have never worked on a Corvette I have not fixed but I am not much of a electrical guy either so ,nothing another $1000.00 worth of parts can't fix .. It's comment deal .. It was 110% here in Houston today ,what's a guy to do ..
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Old 07-11-2019, 05:59 PM
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Update : Installed two new switches High /Low switch and a pig tail for both NOTHING . I did the deal to clear 09 code . The 09 code is the code that turns off the compressor when it runs out of Freon witch mine did and sometimes the code stays in the system so they is a deal to clear it , NO that did not work either ..?? so going to find out try to find out witch one for the controllers is not working right ,controller buttons or the A/C controller or the ECM .. I will send them off to have them tested and rebuild if need be .. Well after a few more test to see if I can figure it out myself ??? If not , spend MORE MONEY .... Nobody her in Houston knows how to figure it out .. SADNESS.. Well I do have temp air two alligator clips and two feet of wire .. That will work for now ... I am in Houston 110 % every day got to have air ..
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Old 07-11-2019, 10:53 PM
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Have you actually pulled the codes for the car (not AC control head) to see if there are any. There are a few codes for AC operation and you should make sure there are not any.


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Old 07-12-2019, 10:16 AM
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Yep I have actually pulled the codes off the OBD-1 and I got 2-H-codes from an bad alternator plug ,nothing else .. No A/C codes al all .. Well I have been putting all efforts on the A/C stuff I installed under the hood why ?? The system was working before it ran out of Freon so the only thing I did was replace all under hood stuff so Ok nothing on the inside was touched so nothing wrong with that ???? . I have I think eliminated all the under hood all new parts ,replaced the switches ,all good now . Well nothing left but the inside stuff . Thanks for the pic I have a manual but I have not seen this pic of the control head .. Not being a Ele. guy this helps . Being a HP guy this is all Greek to me but I am learning . Can/t find anybody ( That I trust ) to look at the thing . Its was in one shop he said he charged it but without it running did he ?? it has some R134a in it now much ???. I am going to put some in myself to see if that helps .. well I had to pay a bill ,that giving money away for nothing way over that .. Going to this shop in the morning old school guys said that have a Tech -1 and would see if they well (might ) have a few tips to help get it going .. He has restored a 93 as well so he said he felt my pain .. Thanks for all the help . The problem is at the tip of my finger and beyond .. LOL
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Old 07-12-2019, 12:27 PM
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I hadn't seen this thread Radar. You've got more knowledgeable folks helping you than me in WVZR-1 and Pcolt but since I just went through a similar process with my A/C I'm going to keep watching and commenting if I see something.

I have to agree with what Pcolt said, the ECM might not be sending a signal to actuate the compressor because it's not being told to by some component that affects the function of the A/C. You might find the fix for your A/C by fixing something in an apparently unrelated system. I also, for my own car, think about all the electrical connectors scattered all over the car. If any one of them has a bad connection it could impact multiple systems, and grounds - OMG.

Regarding the ODB diagnostics, I've just ordered a bluetooth dongle for the diagnostic connector and I've picked out a couple pieces of software, one for my MS Surface and one for my android phone. I'm going to see if either is useful because I'm going to have to get into my EFI after the 'corvette driving season' here in NJ.
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