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1995 Cutlass Ciera AC


mptc
04-22-2014, 11:43 PM
Question regarding air conditioning. Is the AC Refrigerant Pressure Sensor the same thing as the AC Refrigerant Pressure Transducer? Do they perform the same function? My Cutlass Ciera does not have a high and low cut-off switch. Is there a source for GM Part number for this piece?

Thank you in advance.

mptc

brcidd
04-23-2014, 09:14 AM
Yes, they are the same. You have a pressure transducer (three wires on high side line) and you indeed have a high and a low cut-off- the car's computer decides that. You have a variable stroke compressor that does not use a cycling switch because it does not cycle by design.

The number one cause of compressor not coming on is loss of refrigerant due to a leak- your V-5 compressor will run with only 5 ounces refrigerant in it- factory spec is nearly 32 ounces or so (on underhood label)

4 cylinder or 6 cylinder engine? they may be different a/c systems.

Tech II
04-23-2014, 09:56 AM
On the old pressure cycling switch of the old CCOT system, you could jumper out the switch to see if that was the problem.....you can't do that with the pressure switch.......

Have you checked hi/lo pressures with car off? should be close to ambient temp, for example, if it is 70 F outside on a cold engine, hi/lo = 70 psi......if much lower, you have a leak.....

Do you have access to a scan tool? Does it read the same a/c pressure as the gauges?

mptc
04-23-2014, 11:17 AM
It has a 3.1L V-6.

mptc
04-23-2014, 04:17 PM
On the old pressure cycling switch of the old CCOT system, you could jumper out the switch to see if that was the problem.....you can't do that with the pressure switch.......

Have you checked hi/lo pressures with car off? should be close to ambient temp, for example, if it is 70 F outside on a cold engine, hi/lo = 70 psi......if much lower, you have a leak.....

Do you have access to a scan tool? Does it read the same a/c pressure as the gauges?

I do not have a scan tool...at least not an OBD1. What I did do is with the ignition on and the engine off and the pressure sensor disconnected and the ac selector to the "max" position with a digital volt meter I jumpered reference (gray) wire and the signal (red/black) wire and it measured 4.84 volts which is below the 4.92 (high end) volts. Using DVM I connected the reference (gray) wire to ground. It measured near 5 volts (4.98). I also connected the reference (gray) wire and the ground (black) wire and it measured 5 volts (which is reference voltage). So I know the ground wire is good. In addition I did replace the signal wire (red/black).

The sensor is a new replacement. I have tried 2 different PCMs (used) with the same results. I believe the wiring and connections are all good. Now the sensor may be a lemon. Or it could be that the code (1530) is present and until it is cleared it won't operate the compressor. Beyond that I am at a loss of what is next.

Tech II
04-23-2014, 07:47 PM
have you checked pressure in the system with gauges?

brcidd
04-23-2014, 08:47 PM
It takes at minimum 47 psi for compressor to be enabled- have you measured signal voltage with transducer plugged in. It should be somewhere near 1 volt as I recall at ambient of 70 deg and compressor off.

Put some gauges on it- you may have an empty system and the transducer and computer aredoing waht they are suposed to- keep the compressor off.

mptc
04-23-2014, 08:48 PM
have you checked pressure in the system with gauges?


Not lately. The system has been checked, drained and recharged previously (last fall) when I was still having trouble with it. It held the pressure, no leaks or any indication of leaks. I quit working on it through the winter.

mptc
04-23-2014, 08:52 PM
It takes at minimum 47 psi for compressor to be enabled- have you measured signal voltage with transducer plugged in. It should be somewhere near 1 volt as I recall at ambient of 70 deg and compressor off.

Put some gauges on it- you may have an empty system and the transducer and computer aredoing waht they are suposed to- keep the compressor off.

I have no way of measuring the signal voltage with the transducer plugged in. No scan tool.

Tech II
04-24-2014, 07:44 AM
You can back probe the signal wire while it is plugged in to read the signal with the key on.......Just because it was charged last year, does not mean it is charged this year.....these compressors are famous for leaking at the front seal, and also at the service valves....

One more thing.....the place you should really back probe the signal line, is at the ECM....this will tell you the integrity of the line, and if the ECM is receiving the signal....

mptc
04-24-2014, 11:18 AM
You can back probe the signal wire while it is plugged in to read the signal with the key on.......Just because it was charged last year, does not mean it is charged this year.....these compressors are famous for leaking at the front seal, and also at the service valves....

One more thing.....the place you should really back probe the signal line, is at the ECM....this will tell you the integrity of the line, and if the ECM is receiving the signal....

I will try that this weekend and report back. Should I be looking at 1 volt? Is the 70 degrees ambient temp the outside temp? If it is we won't be there for another month or so.

mptc
04-26-2014, 01:08 PM
You can back probe the signal wire while it is plugged in to read the signal with the key on.......Just because it was charged last year, does not mean it is charged this year.....these compressors are famous for leaking at the front seal, and also at the service valves....

One more thing.....the place you should really back probe the signal line, is at the ECM....this will tell you the integrity of the line, and if the ECM is receiving the signal....

Okay...back probed signal wire at ECM. The specs call for voltage of 0.1 volts at 0 psi up to 4.9 volts at 450 psi or more. The best I could get was 0.01 to 0.03 volts with DVM set at 20. So basically no voltage. I did this with the key on, engine off and the AC switch at max. I also did it with the key on, engine on and the AC switch set at max. (Note the ambient (outside) temp is 50 degrees).

Tech II
04-26-2014, 05:01 PM
That voltage means you have no refrigerant in your system....no wonder it won't run...this will be verified with gauges attached.....

mptc
07-16-2014, 11:41 PM
That voltage means you have no refrigerant in your system....no wonder it won't run...this will be verified with gauges attached.....

Okay...here is the update.

1) I had the refrigerant drained (it only had 5 oz. in it). However it held the vacuum for several minutes (indicating no leak in the system).

2) I replaced the a/c pressure sensor (the one I bought previously off of eBay was evidently not compatible with the 95 Ciera 3.1L). In addition, the O-ring had a chunk missing. So that was replaced when putting in the new a/c pressure sensor.

3) The new sensor did not work. I was getting the same .02 or .03 voltage on the signal wire at the PCM (with key on, engine not running and a/c selector switch on).

4) I disconnected the pressure sensor connector and jumpered the reference line (5 V) with the signal wire (according to diagnostic flow chart) it was reading 4.97 volts on the signal wire at the PCM and the secondary cooling fan kicked on (which it should) indicating that the wiring was good.

5) So the system was drained once again. I put the "original" a/c pressure sensor back in (not the one from eBay but previous to that). Now I am getting voltage of 1.10 on the signal wire at the PCM (with the key on and the a/c selector switch turned on). But no secondary fan, no compressor nothing.

So the a/c pressure sensor is operating. The wiring from the a/c pressure sensor to the PCM is good. I can jumper the compressor and it will kick on. The system is charged and holds a vacuum (no leaks).

What am I missing? I have been at this on and off for 2 years.

HELP!

mptc

mptc
08-12-2014, 07:09 PM
I have a scan tool read codes and none were present (looking for 1530). I had them cleared anyway. When monitoring the A/C the pressure read 101.7 and the tool showed that the A/C was being requested but the compressor was not running and no cool air. This in addition to the information in the previous post has me at a complete loss as to where to look next.

Any help would be greatly appreciated!

mptc

DeltaP
08-12-2014, 07:29 PM
1) I had the refrigerant drained (it only had 5 oz. in it). However it held the vacuum for several minutes (indicating no leak in the system).
__________________________________________________ ________________________
If the system only had 5 oz in it and then it held the vacuum for only several minutes then you have a leak! What don't you understand?

mptc
08-13-2014, 11:09 AM
That was before it was recharged, which was about a month ago. Yesterday the scan tool read 101.8 psi. So there is refrigerant in the system. No pressure no refrigerant.

Tech II
08-13-2014, 11:23 AM
Ok, on a cold engine, the pressure reading on the scan tool should be approx. ambient air......so if the car was not started, and the key is just turned to on, and you turn your ac on, your pressure reading on the scan tool should be close to ambient air....80F outside air, should register 80 psi on the scan tool.....

If it is, and your PCM data shows an ac request, then the next step is to check the ac clutch relay......first remove it....probe the 4 legs with a test light....two legs should be hot....the other two legs are the control circuit and the output circuit to the compressor clutch.....

If two legs are not hot, check your ac clutch fuse......

If they are, try swapping the ac relay with another relay......then start car, and see if compressor comes on......

If it doesn't, have someone feel the relay, while you turn the ac on and off....if it doesn't click, then you will have to check the integrity of the control wire from the PCM to the relay, to see if it is open...if it is not, bad PCM....

If it does click, and the compressor does not come on, then you have to check the integrity of the wire from the relay to the compressor clutch...

DeltaP
08-13-2014, 12:16 PM
I might add that the clutch assy could be so worn that the gap is excessive and the magnetic coil just can't pull or hold it in.

Tech II
08-13-2014, 08:23 PM
DeltaP, in post #14, he jumpered the clutch and it ran....

mptc
09-07-2014, 11:32 PM
Okay....checked everything and back probed the control wire from the a/c clutch relay to the PCM and the clutch clicked. I did the same for the secondary cooling fan (which is supposed to engage when selecting the A/C). Same thing the secondary fan engaged. So one would assume a bad PCM.

But here is the deal....I have purchase 2 other PCMs. Both from a salvage yard in Wisconsin on two separate occasions. So including the original PCM, I now have 3 PCMs all displaying the same problem. What are the odds of that happening?

Tech II
09-08-2014, 08:51 AM
I guess it is back to square one......

Need the engine cold first thing in the morning.....

Need gauges on the A/C system.........

Key on, engine not running.....

P0530 must not be set....if it is, clear it.....

Does the pressure reading on the scan tool, equal the pressure reading on the gauges(hi and lo should be equal)? Is the pressure close to ambient air?

If yes to all, start car....turn AC on....does the PCM recognize an AC request on scan tool?

If it does, and pressure reading is ok, then the PCM should be grounding the AC clutch relay.....but apparently it isn't.....

Now, you replaced the sensing line(red/blk) from the sensor to the PCM....

You also said you back probed the control wire(dk green/white) from the PCM to the AC clutch relay and it clicked.......so with the car running, AC requested and blower on, watch the pressure data on the scan tool.....now back probe the control wire to ground again......the clutch should engage, and you should feel cooling, and the pressure data on the scan tool should drop to 30-40 psi......does it do this? Do you get cooling? Do the cooling fans come on? Just do this for a few seconds......

If the compressor comes on, the cooling fans come on, the pressure reading is ok(30-40), then I think you have to check the integrity of that dk green/white wire back to the PCM....it could be an open wire, since you have replaced the PCM.....

mptc
09-01-2018, 04:22 PM
I am back...it has been a long while. The AC is fixed. I replaced the wire from the PCM to the A/C compressor clutch relay including new terminals at the PCM side and the relay side. I also did some diagnostics on the secondary fan relay...which is supposed to engage when A/C is selected. I tested the wire from the pcm to the secondary fan relay. It showed no resistance (.000). I replaced it anyway and what do you know...the compressor clutch kicked on. I also discovered a bad crimp connection in the wire leading from the compressor clutch relay and the compressor plug. I appreciated the patience and help to a novice (at best) budding mechanic (I use that term in the loosest sense).

I do have a new question/request. I am looking to replace the battery cables both negative (which is no problem) and positive which has been discontinued. It is an unusual cable (GM 12157254). It has the wire that leads to the starter but it also has a secondary wire that splits into 3 fusible links (one leading to the ignition, one leading to the Anti lock brake relay and not sure where the other leads but shouldn't be hard to figure out). Is anyone aware of a source for that type of positive battery cable? If not is there a "work around" using a more conventional positive battery cable.

Thank you in advance for any assistance.

mptc

Tech II
09-01-2018, 09:56 PM
You can get any pos bat cable of the correct length.....if the fuseable links are ok, just cut them as close to the starter as possible and add "eyelets"(aka ring terminal) to them to connect them to the post on the starter with the pos battery cable....

https://mobileimages.lowes.com/product/converted/461740/4617404.jpg

mptc
09-04-2018, 07:10 PM
It is about 20" from where the pos. cable connects to the starter. The current fusible links are too short to cover that distance. Most of the fusible links I have sourced are about 9" long. Still too short. Is it possible to get 14 and 16 gauge fusible link wire and cut it to the length I need and then crimp the appropriate eyelets onto one end and use a 3 way connector (male and female) to connect to the ignition wire, etc.? Or just butt connect them individually?

Thanks,

mptc

Tech II
09-04-2018, 09:33 PM
That should work.....

Just remember:

An electrical fusible link is a type of electrical fuse that is constructed simply with a short piece of wire typically four American wire gauge sizes smaller than the wire that is being protected. For example, an AWG 16 fusible link might be used to protect AWG 12 wiring. Electrical fusible links are common in high-current automotive applications. The wire in an electrical fusible link is encased in high-temperature fire-resistant insulation to reduce hazards when the wire melts.

mptc
09-04-2018, 10:39 PM
So would you suggest 3 - 9" fusible links (2-14 gauge and 1-16 gauge) coming off the stud on the starter and then connect 10 gauge wires to each of those terminating at or close to their point of origin?

thanks,

mptc

Tech II
09-05-2018, 08:17 PM
What wire size did you come up with for the circuits?

Are all 3 circuits the same size or different?

For example, if all three circuits are the same size, let's say 14 gauge, the you will use 3-18 gauge fusible links.....

mptc
09-05-2018, 08:37 PM
What wire size did you come up with for the circuits?

Are all 3 circuits the same size or different?

For example, if all three circuits are the same size, let's say 14 gauge, the you will use 3-18 gauge fusible links.....


Actually 2 are 14 gauge and 1 is 16 gauge.

mptc

Tech II
09-06-2018, 11:17 AM
I found a wiring diagram, it shows all three circuits being 2.0(metric)...

Are you sure? My wiring diagram could be wrong....

mptc
09-06-2018, 01:21 PM
I found a wiring diagram, it shows all three circuits being 2.0(metric)...

Are you sure? My wiring diagram could be wrong....

I initially took the information from my subscription to All Date DIY. But I also verified by looking at the wiring itself. There are 3 fusible links. 2 are gray and 1 is black. The black is 1.0 (metric) and the gray is 2.0 (metric). The other gray has no stamp on it but assuming it is 2.0 because of the color and the size compared to the other gray.

mptc

mptc
09-06-2018, 08:17 PM
Another approach...

The new positive battery cable I am looking at is 4 gauge with an 8" 12 gauge lead wire. Is it possible or advisable to take the 12 gauge lead and splice and solder a connection of the 3 fusible links (2-14 gauge and 1-16 gauge) to the 12 gauge lead. Heat shrink the connection and then individually connect the fusible links to their corresponding wires that lead to their terminal point?

mptc

Tech II
09-07-2018, 12:52 PM
This is my diagram:

As you can see, the lead coming off the bat cable is 13, so the line coming off your new cable would be too small, at 12g(3m)......the 12g would not be big enough to carry the current for the 3 circuits if they ran at max current....

the diagram does show, B and G links being 14g and the C link being 16g.....so I would just get the cable without the lead and just use the three lengths of fusible links with an eyelet to attach to the solenoid.....make sure the 16g goes to the correct circuit....

http://i1208.photobucket.com/albums/cc376/gmtech7/Cutlass%20Ciera.png

mptc
09-07-2018, 04:09 PM
How about this battery cable from Rock Auto? It has an 8 gauge lead wire.
If not I will go with the no lead wire battery cable and use the fusible link wire method.


https://www.rockauto.com/en/moreinfo.php?pk=915434&cc=1217180&jsn=418

Thanks for your patience on this.

mptc

Tech II
09-07-2018, 09:34 PM
According to the wiring diagram, it should be 6g....

I am confused.......were these fusible links attached at the starter solenoid or at the battery?

mptc
09-08-2018, 12:33 AM
According to the wiring diagram, it should be 6g....

I am confused.......were these fusible links attached at the starter solenoid or at the battery?



Here is a photo of the original positive battery cable. The fusible links come off the lead near the battery terminal.

mptc

Tech II
09-08-2018, 09:04 PM
Ok, I was confused....I thought the fusible links were attached at the starter, not the battery....

According to the wire diagram, that wire should be a 13m, or 6g....

Now a 6g can handle the three circuits while an 8g, can't(safely)....you can run two circuits off the 8g, and then you can run another fusible link circuit off the bat bolt to the third circuit.....

mptc
09-09-2018, 08:09 PM
Ok, I was confused....I thought the fusible links were attached at the starter, not the battery....

According to the wire diagram, that wire should be a 13m, or 6g....

Now a 6g can handle the three circuits while an 8g, can't(safely)....you can run two circuits off the 8g, and then you can run another fusible link circuit off the bat bolt to the third circuit.....

Great idea. Do I crimp on a loop terminal (like the photo you attached earlier)? Then do I place it behind the battery terminal and the battery bolt will pass through it as it threads into the battery?

mptc

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