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post #1 of 16 (permalink) Old 06-13-2016, 05:36 AM Thread Starter
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AC issue

In the three plus years I've owned my camaro the ac has always worked. Although it never blew frigid air just cool enough to be comfortable.

Yesterday it was in the mid 90's and as I was driving I noticed the air was not very cool at all and then eventually it was just plain hot. I always meant to recharge the system but hadn't done it yet.

So I got one of those cans of refrigerant with a gauge and tried to recharge it and I noticed that the compressor clutch wasn't spinning at all. I don't think any refrigerant went into the system because the gauge on the can never moved when I pulled the trigger.

Is my compressor toast?? I read on Ls1 tech that our cars have a low pressure cut off that will not let the compressor cut on if the pressure is too low. I'm wondering if that may have happened. I know it's needed charged for awhile but lazy me hasn't done it yet lol. Any help is appreciated

110k, Bright Red, Hard top, Moroso cold air, Trick flow ceramic intake elbow, SLP 3" Y pipe, Random tech high flow cat, Borla adjustable cat back with DHM cutout, MSD 8.5mm plug wires, Summit polished diff cover, March crank pulley, V8 shock tower brace, core shifter/billet hurst, Sway bars, Hotchkis lower control arms, welded subframe connectors, lakewood drive shaft loop, non cracked dash
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post #2 of 16 (permalink) Old 06-13-2016, 07:07 AM
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Yes, there is a safety switch that does not allow compressor to run when r134 pressure gets too low.

You need to consult 95 service manual to see which wires on compressor relay to jump to get compressor on long enough to take in the r134.

However, only jump relay long enough to get enough r134 in system so compressor will run on it's own.

Another problem you may have is; if pressure in system falls below atmospheric air pressure, air & moisture will be drawn into system. This is a mucho bad thing as moisture causes the system oil to create acids that attack metal parts of system.

It would be best to have r134 gauge set attached to system when you attempt to recharge system. If pressure in system is below 14 psi, with compressor running, you have moisture in system.

It will need to be flushed & vacuumed out before recharging. If you do not, your compressor will fail in a short time, as well as condenser & evaporator.
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post #3 of 16 (permalink) Old 06-14-2016, 05:28 AM Thread Starter
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Ok thanks man for the info. My friend is an ac tech and he has gauges and a vacuum pump he said it's not very difficult to bleed and vacuum out the system. I'm not positive at what psi the safety switch shuts down the compressor but hopefully the pressure isn't below 14psi. I know there's a chance that my compressor just went out also so it will be good to eliminate all other possibilities first, hopefully that's not the case.

110k, Bright Red, Hard top, Moroso cold air, Trick flow ceramic intake elbow, SLP 3" Y pipe, Random tech high flow cat, Borla adjustable cat back with DHM cutout, MSD 8.5mm plug wires, Summit polished diff cover, March crank pulley, V8 shock tower brace, core shifter/billet hurst, Sway bars, Hotchkis lower control arms, welded subframe connectors, lakewood drive shaft loop, non cracked dash
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post #4 of 16 (permalink) Old 06-19-2016, 03:14 AM Thread Starter
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Unhappy

[QUOTE=cocobolo95;954689]Yes, there is a safety switch that does not allow compressor to run when r134 pressure gets too low.

You need to consult 95 service manual to see which wires on compressor relay to jump to get compressor on long enough to take in the r134.

However, only jump relay long enough to get enough r134 in system so compressor will run on it's own.

Another problem you may have is; if pressure in system falls below atmospheric air pressure, air & moisture will be drawn into system. This is a mucho bad thing as moisture causes the system oil to create acids that attack metal parts of system.

It would be best to have r134 gauge set attached to system when you attempt to recharge system. If pressure in system is below 14 psi, with compressor running, you have moisture in system.

It will need to be flushed & vacuumed out before recharging. If you do not, your compressor will fail in a short time, as well as condenser & evaporator.[/QUOTE



Got a chance to work on my car for a few hours yesterday to try and diagnose what's going on with the ac. My friend who's an ac tech put his gauges on the system and it was reading about 20psi, so low but not super low. So he put some refrigerant in and got the psi up to about 30 but the compressor still didn't turn on.

Next we removed the relay for the compressor and ran a jumper wire from it to the battery and the compressor came on and the air started getting cool inside the car. It seemed to run perfect not making any noises.

Next he checked to make sure that the relay wasn't bad by putting an identical relay (i think the one that runs the fog lights) and the compressor still didn't run.

So then we checked the power plug that goes into the compressor and it was plugged in tight.

Then he thought that maybe the ac pressure sensor might be bad so we called O'reilleys and they had one in stock so we drove to the store and the very nice manager let us put it on the car but still no dice

So what could still be keeping it from running? Could the ac control switch inside the car be not working all of a sudden? Or maybe a bad wire between the relay and the compressor. Thanks in advance for your help.

110k, Bright Red, Hard top, Moroso cold air, Trick flow ceramic intake elbow, SLP 3" Y pipe, Random tech high flow cat, Borla adjustable cat back with DHM cutout, MSD 8.5mm plug wires, Summit polished diff cover, March crank pulley, V8 shock tower brace, core shifter/billet hurst, Sway bars, Hotchkis lower control arms, welded subframe connectors, lakewood drive shaft loop, non cracked dash
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post #5 of 16 (permalink) Old 06-19-2016, 07:53 AM
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Since you jumped the points of relay and compressor ran, we know that points power supply is good, as well as wiring to compressor.

However, a relay is made up of 2 components (1) the points that carry the power to compressor. And (2) the relay control which is a coil that energizes and creates a magnetic field to make relay points close.

I suspect you have trouble on the coil side of relay wiring.

With key on, see if you have battery voltage at place on relay connector that terminal 85 of relay plugs into. If no, probably splice S165 which has orange wire and is located about 3 inches from wire breakout of underhood electrical center, is bad. Or the orange wire going from splice S165 to terminal 85 of relay connector.

If all is well with power going to relay coil, then you must check the ground wire for the relay coil. It is the dark green/white wire that runs from terminal 86 of relay to connector D cavity 8 of pcm. 1st test is with relay in. Find dark green/white wire coming from terminal 86 of relay. Bare a small area so you can connect another wire.

With car running, touch the wire you just connected to dark green/white wire, to a good ground. If compressor now kicks in, you have a ground problem with coil part of relay. If this didn't cause compressor to turn on, make sure you have your wire connected to the dark green/white wire from terminal 86 of relay.

If compressor ran, shut car off, disconnect battery and remove the wire you used for last test.. Remove relay, and disconnect pcm connector D It's the blue connector.

Use multimeter set to resistance setting and connect one probe to terminal 86 of relay and other probe to connector D cavity 8 of pcm. Dark green/white wire all the way. You are testing to see if you have continuity on this wire. Continuity will give a meter reading of 0 ohms or near 0 ohms.

If you have continuity, I'm out of ideas. If no continuity on dark green/white wire, check connector C100. Its 1 of the 2 large connectors near where the pcm is. It will be on the inner fender well.

Disconnect connector C100. You are looking for the dark green/white wire in cavity B of connector. Again put 1 lead of meter, set to ohms, on terminal 86 of relay. Other probe on dk grn/wht wire of cavity B of C100. Test the side of connector going away from pcm. If you don't have continuity, problem is in on wire between relay and C100. Or the C100 connector

If you have continuity, continue test. Put 1 probe on side of C100 cavity B that is coming from pcm. 2nd probe to pcm connector D cavity 8. Of course with it disconnected from pcm. If you have continuity again, My guess there is a ground problem with pcm.

If no continuity Then wire running from C100 to pcm conn D or other half of C100 is bad.

Last edited by cocobolo95; 06-19-2016 at 08:11 AM.
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post #6 of 16 (permalink) Old 06-20-2016, 04:21 PM Thread Starter
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Quote:
Originally Posted by cocobolo95 View Post
Since you jumped the points of relay and compressor ran, we know that points power supply is good, as well as wiring to compressor.

However, a relay is made up of 2 components (1) the points that carry the power to compressor. And (2) the relay control which is a coil that energizes and creates a magnetic field to make relay points close.

I suspect you have trouble on the coil side of relay wiring.

With key on, see if you have battery voltage at place on relay connector that terminal 85 of relay plugs into. If no, probably splice S165 which has orange wire and is located about 3 inches from wire breakout of underhood electrical center, is bad. Or the orange wire going from splice S165 to terminal 85 of relay connector.

If all is well with power going to relay coil, then you must check the ground wire for the relay coil. It is the dark green/white wire that runs from terminal 86 of relay to connector D cavity 8 of pcm. 1st test is with relay in. Find dark green/white wire coming from terminal 86 of relay. Bare a small area so you can connect another wire.

With car running, touch the wire you just connected to dark green/white wire, to a good ground. If compressor now kicks in, you have a ground problem with coil part of relay. If this didn't cause compressor to turn on, make sure you have your wire connected to the dark green/white wire from terminal 86 of relay.

If compressor ran, shut car off, disconnect battery and remove the wire you used for last test.. Remove relay, and disconnect pcm connector D It's the blue connector.

Use multimeter set to resistance setting and connect one probe to terminal 86 of relay and other probe to connector D cavity 8 of pcm. Dark green/white wire all the way. You are testing to see if you have continuity on this wire. Continuity will give a meter reading of 0 ohms or near 0 ohms.

If you have continuity, I'm out of ideas. If no continuity on dark green/white wire, check connector C100. Its 1 of the 2 large connectors near where the pcm is. It will be on the inner fender well.

Disconnect connector C100. You are looking for the dark green/white wire in cavity B of connector. Again put 1 lead of meter, set to ohms, on terminal 86 of relay. Other probe on dk grn/wht wire of cavity B of C100. Test the side of connector going away from pcm. If you don't have continuity, problem is in on wire between relay and C100. Or the C100 connector

If you have continuity, continue test. Put 1 probe on side of C100 cavity B that is coming from pcm. 2nd probe to pcm connector D cavity 8. Of course with it disconnected from pcm. If you have continuity again, My guess there is a ground problem with pcm.

If no continuity Then wire running from C100 to pcm conn D or other half of C100 is bad.
Ok thanks a lot man for all your help I told my friend to read your post and he said we can check those wires to see if that's where the problem is. All of that stuff is a little over my head but my friend is very knowledgable and understands your instructions hopefully we can get it fixed without too much trouble.

Also I wonder if the head unit could be going bad or at least the ac switch itself. I looked on eBay and theres plenty of them for sale for around 40 bucks but I don't wanna just throw parts at it if that might not even be the problem.

I meant to reply last night to your post but cleveland finally won a championship and the rest of the night was a blur lol.

110k, Bright Red, Hard top, Moroso cold air, Trick flow ceramic intake elbow, SLP 3" Y pipe, Random tech high flow cat, Borla adjustable cat back with DHM cutout, MSD 8.5mm plug wires, Summit polished diff cover, March crank pulley, V8 shock tower brace, core shifter/billet hurst, Sway bars, Hotchkis lower control arms, welded subframe connectors, lakewood drive shaft loop, non cracked dash
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post #7 of 16 (permalink) Old 06-20-2016, 08:01 PM
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I don't think that ac control unit is bad. But you can find out for sure if you put car on obd 1 scanner that does real time sensor data. One of the data categories is ac request. If ac control unit is good, when you switch ac on the scanner will show ac request as yes.

If you don't have acess to an obd 1 scanner, may I suggest downloading the free obd 1 scan program called "scan9495". It was made for our 93-95 f-body cars. It scans for regular codes, ABS & SIR codes. It does running sensor scans and will log data to a file for later playback. And it tests engine & auto trans actuators.

Get at www.mediafire.com/?0elo4c935uc5s

You will need Microsoft Net Framework version 4.0 or newer to use scan9495. It is available at link I posted or Microsoft website.

You will need a 16 pin obd 1 aldl to usb port of pc cable to read car's pcm. Get at OBD Diagnostics

Last edited by cocobolo95; 06-20-2016 at 08:03 PM.
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post #8 of 16 (permalink) Old 06-21-2016, 05:56 AM Thread Starter
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Quote:
Originally Posted by cocobolo95 View Post
I don't think that ac control unit is bad. But you can find out for sure if you put car on obd 1 scanner that does real time sensor data. One of the data categories is ac request. If ac control unit is good, when you switch ac on the scanner will show ac request as yes.

If you don't have acess to an obd 1 scanner, may I suggest downloading the free obd 1 scan program called "scan9495". It was made for our 93-95 f-body cars. It scans for regular codes, ABS & SIR codes. It does running sensor scans and will log data to a file for later playback. And it tests engine & auto trans actuators.

Get at www.mediafire.com/?0elo4c935uc5s

You will need Microsoft Net Framework version 4.0 or newer to use scan9495. It is available at link I posted or Microsoft website.

You will need a 16 pin obd 1 aldl to usb port of pc cable to read car's pcm. Get at OBD Diagnostics
Ok thanks, My friend has a 95 corvette with a bunch of engine work done to it i'm gonna ask him if he has scanning equipment for his car. I'm assuming it would work on mine since it has basically the same power plant.

Also I was talking to my friend sunday who's a mechanic and he said one way to check if the ac switch inside the car is bad is by turning on the defrost to see if compressor kicks on. But like you said I highly doubt that the head unit suddenly went bad but stranger things have happened.

110k, Bright Red, Hard top, Moroso cold air, Trick flow ceramic intake elbow, SLP 3" Y pipe, Random tech high flow cat, Borla adjustable cat back with DHM cutout, MSD 8.5mm plug wires, Summit polished diff cover, March crank pulley, V8 shock tower brace, core shifter/billet hurst, Sway bars, Hotchkis lower control arms, welded subframe connectors, lakewood drive shaft loop, non cracked dash
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post #9 of 16 (permalink) Old 08-21-2016, 12:03 PM Thread Starter
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So I finally got to work on my car yesterday after over a month of extremely hot weather here in Raleigh and not wanting to mess with it. So my friend read on another forum of a guy having the same issue with his 95 z28 and he said he unhooked his battery for about 10 minutes and the compressor started working. So we tried it not thinking that it would and it worked!!!

The compressor started working like its supposed to and the air inside the car started getting cool but not as cool as it should be. My friend put his gauges on the system and it was a little low so we charged it up to around 35-40 psi and the air got a little cooler but not cold yet.

Then he noticed that the hi and low ac lines coming out of the expansion valve were not getting cold and sweating like they should with the compressor running. But the expansion valve itself was cold and sweating??

So we are thinking that the expansion valve might not be opening up all the way and only letting a little bit of refrigerant out so make the air sort of cool inside the car but not enough to make those lines get cold like they are supposed to.

So then he told me to drive the car a little bit and see what happens, and a minute after I started driving the compressor shut off. He thinks that the pressure may have gotten too high from the expansion valve not working and cut off the compressor.

He wasn't able to check the pressure on the high side cuz something was broken on his gauges but he thinks the pressure is to high from the blockage. So i'm thinking of changing the expansion valve and seeing if that's my issue now. It seems like that has to be it with it being cold and the lines coming out of it staying warm.

Any ideas?

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post #10 of 16 (permalink) Old 08-21-2016, 12:11 PM
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Be aware that changing the valve involves creaking open the system. This will require a vacuum pump to vacuum out system, before charging with R134.
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post #11 of 16 (permalink) Old 08-21-2016, 08:06 PM Thread Starter
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Thanks for the reminder. I forgot to mention that very important detail, thankfully my friend is an ac tech and he has the vacuum pump to do that.

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post #12 of 16 (permalink) Old 08-22-2016, 04:46 PM Thread Starter
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I bought the only Lt1 expansion valve in the city of Raleigh today lol so hopefully will be able to change it out saturday and have cool air blowing again!

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post #13 of 16 (permalink) Old 08-29-2016, 05:28 AM Thread Starter
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So we changed the expansion valve saturday and it didn't fix the issue. We are starting to think that maybe the compressor isn't pumping the refrigerant correctly. Because the pressure's are reading pretty normal and the car is dripping condensation but the air inside the car is hot.

Also the low side line coming out of the expansion valve is not getting cold and has no condensation on it. And when my friend put his gauges on the high side and we revved the engine the gauge didn't go up at all it just stayed the same right at about 150. He said that it should be going up if its working correctly.

Also the condenser fan is working so it's not that. It's just kinda a process of illimination at this point but i'm thinking my compressor may be on its way out. Only other thing my friend said is that maybe there is a blockage in the system thats not letting the refrigerant flow.

110k, Bright Red, Hard top, Moroso cold air, Trick flow ceramic intake elbow, SLP 3" Y pipe, Random tech high flow cat, Borla adjustable cat back with DHM cutout, MSD 8.5mm plug wires, Summit polished diff cover, March crank pulley, V8 shock tower brace, core shifter/billet hurst, Sway bars, Hotchkis lower control arms, welded subframe connectors, lakewood drive shaft loop, non cracked dash
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post #14 of 16 (permalink) Old 03-12-2017, 08:53 AM Thread Starter
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So finally got around to working on the ac on my car yesterday and after 8 hours of work the car is fixed! We decided that the compressor was most likely going bad so I rolled the dice and ordered an AC delco from Rock Auto and changed it out and she's fixed.

The worst part about the job was getting the bolt out of the back of the compressor that connects the lines to it. It had lots of loctite on it and had us so frustrated we were about to give up lol. I finally had to weld a piece of steel to a wrench and was able to break it loose! I was surprised at how easy the compressor came out and the new one went back in after that bolt came out though. My friend told me he had to unbolt his front sway bar to get the compressor out on his 98 trans am so at least we didn't have to do that.

110k, Bright Red, Hard top, Moroso cold air, Trick flow ceramic intake elbow, SLP 3" Y pipe, Random tech high flow cat, Borla adjustable cat back with DHM cutout, MSD 8.5mm plug wires, Summit polished diff cover, March crank pulley, V8 shock tower brace, core shifter/billet hurst, Sway bars, Hotchkis lower control arms, welded subframe connectors, lakewood drive shaft loop, non cracked dash
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post #15 of 16 (permalink) Old 03-12-2017, 10:55 AM
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Quote:
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So finally got around to working on the ac on my car yesterday and after 8 hours of work the car is fixed! We decided that the compressor was most likely going bad so I rolled the dice and ordered an AC delco from Rock Auto and changed it out and she's fixed.

The worst part about the job was getting the bolt out of the back of the compressor that connects the lines to it. It had lots of loctite on it and had us so frustrated we were about to give up lol. I finally had to weld a piece of steel to a wrench and was able to break it loose! I was surprised at how easy the compressor came out and the new one went back in after that bolt came out though. My friend told me he had to unbolt his front sway bar to get the compressor out on his 98 trans am so at least we didn't have to do that.
That bolt was a major PITA but nothing a few beers cant take care of.

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