1992 SC300: A/C Troubleshooting
07-14-15, 07:06 AM
#1
1992 SC300: A/C Troubleshooting
Thought I'd just keep a little journal here more or less of my A/C troubleshooting efforts as I go through them, in case it helps anyone in the future. I've done a bit of searching and I find a little bit of into here and there. So I can kind of consolidate the stuff that pertains to me here. So here we go..
1992 SC300
The A/C has not worked since I've owned the car. The system did have refrigerant in it when I bought it, just did not work (A/C light would blink in the interior). The refrigerant was evacuated a couple years back when I pulled the motor. Now I'm to the point where I'm ready to try and get it working again.
Interesting note is that my car is a 1992. Assuming it was an R12 system, I purchased an EnviroSafe R12a recharge kit since actual R12 is a bit spendy and I heard a lot of good reviews about the R12a stuff. Once I got the kit in the mail, I came to realize my car actually has R134a lines on it. Strange, previous owner must have swapped in an R134a system or something? No idea if he did just the lines, or the condenser too, all I know is I have R134a fittings on my lines. And they are the actual fittings on the lines, not retrofitted fittings.
So, my current plan is that I bought an O-Ring kit. Since the system is empty, I'm going to take this opportunity to replace all the O-Ring seals. Also bought a new drier that I'll install as well. At that point hopefully my system is ready to rock.
I also have the existing issue I mentioned previously where when I got the car the A/C did not work. Basically you hit the A/C button in the car, the light turns on for a few seconds then immediately starts blinking, which from what I've come to understand means that the system did not detect the Mag Clutch engage. I know I cannot feel or hear the clutch engage either which I figured I'd be able to feel or hear something, so that makes sense that the light is blinking. I did try jumpering the signal at the MG CLT relay (pin 5 to pin 3) briefly just to see if I could hear the clutch engaging, and I heard nothing. I verified voltage was present at the relay. So that seems to be a good starting point for troubleshooting. My next idea is that I will jumper 12V directly from the battery to the compressors plug itself to see if I can hear it engage. I did purchase a used compressor off ebay that should be here in a few days just in case I find out I need to replace the compressor itself.
I did the A/C diagnostic test and only had code 21 (solar detector) which makes sense as I was in the garage. But I read code 21 does NOT prevent the compressor from turning on all by itself, so I'm not too worried about that code. Plus like I said, I saw voltage at the relay, so that makes me think the button itself is trying to tell the compressor to turn on.
That's about it for now, I'll keep this updated as I go.
Couple questions I do have for other folks out there since I haven't dealt with A/C systems a lot. It's obvious I'm not an A/C tech, and so a lot of what I'm doing here will not be 'by the books'. I don't have a system to pull a vacuum and all that jazz, but I figured I'd give it a shot anyway, this is a total home brew way I'm going about it here. If I end up having to take it in to get a pro to charge the system, so be it. But I'm going to give it a shot first! So since I'm more or less starting with an empty system, my R12a recharge kit came with a bottle of oil. How much of that should I put in? And when should I put that in, should I put that in first before any Freon?
1992 SC300
The A/C has not worked since I've owned the car. The system did have refrigerant in it when I bought it, just did not work (A/C light would blink in the interior). The refrigerant was evacuated a couple years back when I pulled the motor. Now I'm to the point where I'm ready to try and get it working again.
Interesting note is that my car is a 1992. Assuming it was an R12 system, I purchased an EnviroSafe R12a recharge kit since actual R12 is a bit spendy and I heard a lot of good reviews about the R12a stuff. Once I got the kit in the mail, I came to realize my car actually has R134a lines on it. Strange, previous owner must have swapped in an R134a system or something? No idea if he did just the lines, or the condenser too, all I know is I have R134a fittings on my lines. And they are the actual fittings on the lines, not retrofitted fittings.
So, my current plan is that I bought an O-Ring kit. Since the system is empty, I'm going to take this opportunity to replace all the O-Ring seals. Also bought a new drier that I'll install as well. At that point hopefully my system is ready to rock.
I also have the existing issue I mentioned previously where when I got the car the A/C did not work. Basically you hit the A/C button in the car, the light turns on for a few seconds then immediately starts blinking, which from what I've come to understand means that the system did not detect the Mag Clutch engage. I know I cannot feel or hear the clutch engage either which I figured I'd be able to feel or hear something, so that makes sense that the light is blinking. I did try jumpering the signal at the MG CLT relay (pin 5 to pin 3) briefly just to see if I could hear the clutch engaging, and I heard nothing. I verified voltage was present at the relay. So that seems to be a good starting point for troubleshooting. My next idea is that I will jumper 12V directly from the battery to the compressors plug itself to see if I can hear it engage. I did purchase a used compressor off ebay that should be here in a few days just in case I find out I need to replace the compressor itself.
I did the A/C diagnostic test and only had code 21 (solar detector) which makes sense as I was in the garage. But I read code 21 does NOT prevent the compressor from turning on all by itself, so I'm not too worried about that code. Plus like I said, I saw voltage at the relay, so that makes me think the button itself is trying to tell the compressor to turn on.
That's about it for now, I'll keep this updated as I go.
Couple questions I do have for other folks out there since I haven't dealt with A/C systems a lot. It's obvious I'm not an A/C tech, and so a lot of what I'm doing here will not be 'by the books'. I don't have a system to pull a vacuum and all that jazz, but I figured I'd give it a shot anyway, this is a total home brew way I'm going about it here. If I end up having to take it in to get a pro to charge the system, so be it. But I'm going to give it a shot first! So since I'm more or less starting with an empty system, my R12a recharge kit came with a bottle of oil. How much of that should I put in? And when should I put that in, should I put that in first before any Freon?
07-14-15, 06:20 PM
#2
So I jumpered 12V right from the battery to the 3rd pin on the plug that is attached to the compressor which I believe is for the mag clutch. It does not appear to be engaging. So at this point I'm thinking that I have a bad compressor. So next step will be to install the new one when it gets here. Also at that time might as well install the new o rin g kit and new drier. Then go from there.
07-25-15, 03:28 PM
#3
Installed new compressor, can hear the clutch now when I jumper it, so definitely had a bad clutch on the old one. I also installed new o rings since the system was empty. Also installed a new drier. Wierd that the ones at autozone and oreilly for SC300 didn't work, the dowel location for the ac line was in the wrong spot. The ones they had for an SC400 was correct.
I did find out my lines are in fact r134 retrofitted. I will be charging soon hopefully and seeing if I'm good to go.
I did find out my lines are in fact r134 retrofitted. I will be charging soon hopefully and seeing if I'm good to go.
07-25-15, 09:04 PM
#4
Success!
New compressor, new drier, and new o-rings (mostly, there were a few I couldn't do). Ended up going to my cousins work to fill the system. Pulled a vacuum and held perfect. Put in oil and 30oz of R134a. Pressed the AC button and there was cold air! So happy, don't have to worry about sweating my *** off for the rest of the summer in this thing, so I'll be able to put more miles on her!
Few pics attached.
New compressor, new drier, and new o-rings (mostly, there were a few I couldn't do). Ended up going to my cousins work to fill the system. Pulled a vacuum and held perfect. Put in oil and 30oz of R134a. Pressed the AC button and there was cold air! So happy, don't have to worry about sweating my *** off for the rest of the summer in this thing, so I'll be able to put more miles on her!
Few pics attached.
07-25-15, 10:30 PM
#5
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Success!
New compressor, new drier, and new o-rings (mostly, there were a few I couldn't do). Ended up going to my cousins work to fill the system. Pulled a vacuum and held perfect. Put in oil and 30oz of R134a. Pressed the AC button and there was cold air! So happy, don't have to worry about sweating my *** off for the rest of the summer in this thing, so I'll be able to put more miles on her!
Few pics attached.
New compressor, new drier, and new o-rings (mostly, there were a few I couldn't do). Ended up going to my cousins work to fill the system. Pulled a vacuum and held perfect. Put in oil and 30oz of R134a. Pressed the AC button and there was cold air! So happy, don't have to worry about sweating my *** off for the rest of the summer in this thing, so I'll be able to put more miles on her!
Few pics attached.
Dude,
Nice.
07-25-15, 11:03 PM
#6
I just got my A/C working a couple weeks ago. I feel your relief! We're in the midst of a historic heat wave here. My compressor seal was shot, and my spare compressor had a good seal but a blown clutch. Between the two, everything is working great.
Rock Auto has very good prices on the OEM Denso receiver driers, and although I didn't get it since I wasn't sure yet if my spare compressor would work, they have a new Denso compressor for reman'd prices. I inquired if that was correct and they said it's new if it doesn't say remanufactured, rebuilt, etc.
Rock Auto has very good prices on the OEM Denso receiver driers, and although I didn't get it since I wasn't sure yet if my spare compressor would work, they have a new Denso compressor for reman'd prices. I inquired if that was correct and they said it's new if it doesn't say remanufactured, rebuilt, etc.
07-26-15, 09:30 AM
#7
Nice, Rock Auto has the correct Denso driers too for my year SC300. If you look at the other ones, they have the holes for the dowel pins in the wrong spot. I needed mine same day so that's why I just went to O'reilly. Otherwise I love RockAuto !
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10-30-22, 03:32 PM
#8
Your A/C clutch coil was bad. That's a $49 part online. You can test this on the car by 12V to the coil OR using a continuity tester to see if the coil measures continuity. Its just a very thin wire loop. My minivans just went out, The coil behind the clutch harness behind a metal bracket eroded or burned there and was grounded. $18 at pick-a-part and I got it working again. Only special tool I needed to replace this was a external snap ring plier. Both clutch pulley and coil just slipped off the pump with a few taps from the back. Good luck.
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