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#16
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Concerning the pressure sensor wires...
What are the pressure readings on the car with gauges attached ? If you do not have normal amount of refrigerant in the system... then that switch is working correctly in not letting electricity get to the compressor...
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1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
#17
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When I checked it the pressure was like 90 - fairly normal for the ambient temp. I know the system is pressurized and holding right now.
Ahhhh...forgot to mention that there was no continuity across the pressure switch. So that could be a problem, but if I jumper the leads, I still get no engagement, so that can't be the whole story right?
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Current Mercedes 1979 maple yellow 240D 4-speed Gone and fondly remembered: 1980 orient red 240D 4-speed Gone and NOT fondly remembered: 1982 Chna Blue 300TD Other car in the stable: 2013 VW Jetta Sportwagen TDI / 6-speed MT |
#18
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*bump*
for any ideas?
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Current Mercedes 1979 maple yellow 240D 4-speed Gone and fondly remembered: 1980 orient red 240D 4-speed Gone and NOT fondly remembered: 1982 Chna Blue 300TD Other car in the stable: 2013 VW Jetta Sportwagen TDI / 6-speed MT |
#19
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Ok.. there is a difference between jumpering across the leads....and having 12V going through them...
so make sure it has both ... How about this order.... take 12v to the compressor clutch direct with jumper wire and just see if you get a click and movement. Then start from the compressor and work back with VOM to see where the last place 12v is available for sure in a static situation... of course this will not factor in ' pilot operated' switch settings...but will give a place to start from.. Take out your fuses and clean and reinstall them before you start...or better yet put new ones in just 'on principle ' as MB says...
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1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/showthread.php?threadid=10414 http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
#20
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OK, 12V directly to the compressor leads made lots of sparks and no engagement.
Replacement time? Electrical system is the great unknown for me.....
__________________
Current Mercedes 1979 maple yellow 240D 4-speed Gone and fondly remembered: 1980 orient red 240D 4-speed Gone and NOT fondly remembered: 1982 Chna Blue 300TD Other car in the stable: 2013 VW Jetta Sportwagen TDI / 6-speed MT |
#21
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For those new to this and just watching at this time..... you mean you put 12 volts to the compressor clutch leads.... the two of them.... (?) Some compressors may have other things with leads to them... but that is not what we are talking about .
What colors are the leads ? Which one did you put the direct negative 12v to ? The sparks were at the actual connection points ? Did you burn your fingers ? Ok, at this point in time..do you still have the pressure in the system ? You might could just replace the compressor Clutch... but I do not know if you have the tools to do this...
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1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/showthread.php?threadid=10414 http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
#22
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fixed mine i think
i just wanted to say thanks, the "mercedes guy" at the part store told me there was no pressure switch in there, well i read this thread. found mine, bipassed the pressure switch and the compresser clutch quietyly engaged and ran the whole thing..... now i can recharge it instead of evacuating it and then taking apart the compressor or just putting in a rebuilt one.
man what a d.,' he is like nope if it doesnt engage it is shot, new compressor. joker has no idea what he is talking about, i hat throwing parts at a problem. anyway thanks for the help and i hope you get sorted out. |
#23
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Quote:
I did this by running black jumper cable from neg terminal to the topmost lead (yes, directly on the compressor just south of the belt). Then I snaked the red clip down under the engine well (moved the washer res.) clipped it to a long flat screwdriver (with a plastic handle ( ) and let it dangle on the floor. Connected the red lead to the positive terminal. Then I got under the car and touched the screwdriver blade to the bottom lead. I did have the control cable leads connected at the time. Did it with the car both off and running with AC control engaged. Didn't seem to matter. When I touched the lead, I got lots of sparks. No burns - had my longest screwdriver in use - but it was bright and a bit scary..... Anyway, never heard the clutch move at all - just the sparks popping.
__________________
Current Mercedes 1979 maple yellow 240D 4-speed Gone and fondly remembered: 1980 orient red 240D 4-speed Gone and NOT fondly remembered: 1982 Chna Blue 300TD Other car in the stable: 2013 VW Jetta Sportwagen TDI / 6-speed MT |
#24
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Ok... was trying to determine if the sparks came from behind the clutch in an area which might mean the wires were frayed and contacting...or where you hooked up.... but can't tell from what you did which it might be...
If you still have pressure... then you may can just replace ( in place ) the compressor CLUTCH.... instead of the whole thing... that means not having to deal with the refrigerant... I think there are threads about what tools and suggestions as to what else to take out of the car.. I think the radiator to give you working room... Or you can replace the whole clutch and compressor as a unit .....
__________________
1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/showthread.php?threadid=10414 http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
#25
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The wires look good - when I did the job last year, I replaced the plastic connector end with a new one from the dealership (i.e. resoldered the wires to the leads) - they are still in place, but the POS plastic piece fell apart - (missing German production quality in "Genuine" MB parts). I made very sure they are not contacting anywhere and that the jumper cables were all clear.
Is it possible to have the polarity reversed on the clutch? Not sure if I tried the leads both ways, but I definately didn't try the jumper positions switched..... Thoughts on replacing the clutch versus whole unit? I have all the tools I need (minus a compressor wrench which is a free loaner at AZ) to do the whole unit. In reading, I would have to get other tools to pull the clutch I think? Cost may be about a wash when I consider in the fact that I will still have a (slightly) used compressor body in place? Thanks so much for your advice LM
__________________
Current Mercedes 1979 maple yellow 240D 4-speed Gone and fondly remembered: 1980 orient red 240D 4-speed Gone and NOT fondly remembered: 1982 Chna Blue 300TD Other car in the stable: 2013 VW Jetta Sportwagen TDI / 6-speed MT |
#26
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I don't think polarity matters when you try to jumper the compressor. I always try to ohm out the resistance of the coil. I do not know the exact value for the compressor in question but it should be quite high, may be in the order of a few hundred ohms. Also try to ohm the 2 leads to chassis. It should not conduct. If the coil is burnt or is short to chasis then the you will see sparks. I think it is not recommended to replace the clutch with the compressorr in situ. I don't even know whether it is possible. I have not followed this post closely but it seems to be a bad compressor if you can not engage it directly with 12v.
Good luck.
__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed. W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html 1 X 2006 CDI 1 x 87 300SDL 1 x 87 300D 1 x 87 300TDT wagon 1 x 83 300D 1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry. |
#27
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ah-kay, don't you mean the indications are ...so far... that it is a bad compressor Clutch ?
I do not recommend changing the AC clutch in situ either.. EXCEPT that if someone can find a shop which can do that.. then the rest of the system... mainly the refrigerant... does not have to be messed with ....( this assumes the rest of the system is OK )... a judgment call only the owner can make...
__________________
1980 240d , chain elongation, cam marks reference: http://www.peachparts.com/shopforum/showthread.php?threadid=10414 http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html evap fin cleaning: http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator A/C thread http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html |
#28
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May be LM can help to locate an A/C shop
Quote:
If the OP can find a shop who is willing to replace the clutch in situ, this is a BIG IF, and the OP is willing to pay someone to do that then good luck. It ain't going to be cheap or doable as there are a lot of stuffs in the way. BTW, the jury is still out whether it is the clutch, may be with your electrical knowledge you can help the OP to diagnose more.
__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed. W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html 1 X 2006 CDI 1 x 87 300SDL 1 x 87 300D 1 x 87 300TDT wagon 1 x 83 300D 1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry. |
#29
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WARNING! There is probably a diode in parallel with the coil. If so, you will burn it out if you energize with reversed polarity.
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#30
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The diode is there to protect back emf. It is easy to ohm it out across the terminals if there is a diode or not. The diode is reversed biased across the coil.
__________________
Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed. W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html 1 X 2006 CDI 1 x 87 300SDL 1 x 87 300D 1 x 87 300TDT wagon 1 x 83 300D 1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry. |
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