Re: [MBZ] Why is my ac not working?
Jumpeingr 5 and 7 is what the relay does, so your compressor is good and the clutch coil conducts enough to at least spin it, but that does not mean the KLIMA is good. As I said, the PBCU switches on the compressor by grounding the wire from the low pressure cutout switch, so if the KLIMA is good, grounding that wire indicates that the PBCU is bad for some reason. If there is no voltage present at the low pressure cutout switch, either the wiring or the KLIMA is bad, and if there is but you don't get the compressor to come on when you ground it, the KLIMA is bad. You should also check the OVP relay, as I think the PBCU is protected, and a bad OVP relay will leave you with no or intermittent operation. Peter ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Why is my ac not working?
If the ovp relay was bad you would also not have any tach or electronic idle control, correct? Sent from my iPhone On Jul 14, 2013, at 8:09 AM, Peter Frederick psf...@earthlink.net wrote: Jumpeingr 5 and 7 is what the relay does, so your compressor is good and the clutch coil conducts enough to at least spin it, but that does not mean the KLIMA is good. As I said, the PBCU switches on the compressor by grounding the wire from the low pressure cutout switch, so if the KLIMA is good, grounding that wire indicates that the PBCU is bad for some reason. If there is no voltage present at the low pressure cutout switch, either the wiring or the KLIMA is bad, and if there is but you don't get the compressor to come on when you ground it, the KLIMA is bad. You should also check the OVP relay, as I think the PBCU is protected, and a bad OVP relay will leave you with no or intermittent operation. Peter ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Why is my ac not working?
More than one circuit in there, you can lose one but not the others, I think. Good luck, I hate tracing down automotive electrical problems! One last thought -- make sure the ground at the PBCU is good Peter ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Why is my ac not working?
So I ran a test wire from the plug on pressure switch to ground and compressor started up. So we either have a wiring issue to the pbu or a bunch of bad pbu's? Sent from my iPhone On Jul 14, 2013, at 8:09 AM, Peter Frederick psf...@earthlink.net wrote: Jumpeingr 5 and 7 is what the relay does, so your compressor is good and the clutch coil conducts enough to at least spin it, but that does not mean the KLIMA is good. As I said, the PBCU switches on the compressor by grounding the wire from the low pressure cutout switch, so if the KLIMA is good, grounding that wire indicates that the PBCU is bad for some reason. If there is no voltage present at the low pressure cutout switch, either the wiring or the KLIMA is bad, and if there is but you don't get the compressor to come on when you ground it, the KLIMA is bad. You should also check the OVP relay, as I think the PBCU is protected, and a bad OVP relay will leave you with no or intermittent operation. Peter ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Why is my ac not working?
That is what I would say. Check the ground wire for the PBCU -- no ground = no operation. I'd suspect the wiring on that age car though -- 95 was right in the middle of the magical disintegrating insulation period. Every wire in the car is subject to that problem, not just the engine harness. The rest of the W124s and W126s have crumbling insulation issues as well, just not anywhere near as bad. Peter ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Why is my ac not working?
I'll give you $500 for it. Luther KB5QHUForest Park, IL '98 ML320 Max (168,xxx mi) On 7/13/2013 9:40 PM, Kaleb C. Striplin wrote: I had one clutch fail, but have had many klimas fail. This one has me baffled. Sent from my iPhone ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Why is my ac not working?
The KLIMA Is probably bad -- the signal goes from the PBCU to the KLIMA to the low pressure switch on the receiver/dryer. If the KLIMA relay has burned contact, it won't switch the compressor on no matter what you do as the clutch current goes only through that relay contact set. Check the resistance of the clutch coil as well -- a shorted clutch will simply burn out another KLIMA relay in sort order. Peter ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Why is my ac not working?
I have also tried about or 5 different klimas also. One out of my other 95 and several out of 2.5 that I know work in those cars but do have the 12th pin for temp sensor cutout that the 95 does not. I pulled the Klima apart and I do not see anything that appears burned. In prep for the test it says turn key on, set temp to min and put pos of vm on battery, neg to both terminal one after another and check if battery voltage is present. I am not getting 12 volts at this step. Sent from my iPhone On Jul 13, 2013, at 3:19 PM, Peter Frederick psf...@earthlink.net wrote: The KLIMA Is probably bad -- the signal goes from the PBCU to the KLIMA to the low pressure switch on the receiver/dryer. If the KLIMA relay has burned contact, it won't switch the compressor on no matter what you do as the clutch current goes only through that relay contact set. Check the resistance of the clutch coil as well -- a shorted clutch will simply burn out another KLIMA relay in sort order. Peter ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Why is my ac not working?
The PBCU provides a ground to the voltage signal, so I suspect you don't have voltage at the switch due to a failed wire somewhere between the battery and the pressure switch. I almost forgot -- some engines are equipped with a wide open throttle switch to disconnect the AC compressor at full throttle. If that switch as failed, you won't get AC engagement and no voltage at the PBCU, just as if the low pressure switch was open. I don't know where this switch is in the circuit, but the switch itself is on the throttle linkage. Check for voltage at the pin socket for the KLIMA, this is supplied via the keyswitch. If you don't have voltage at the KLIMA socket for that wire, the AC won't ever come on as the KLIMA relay cannot be energized. You will have to check the KLIMA wiring, I'm not sure if that line is separate or internally connected to the switched positive supply. If you have voltage at the switch but not the connector at the PBCU, you have a wiring failure between the pressure switch and the PBCU or a failed open pressure switch. You can jumper the switch, but you've tried that, right? The system works by the PBCU providing a ground for the relay in the KLIMA, which can be disconnected by an open pressure switch, a failed speed sensor signal (engine speed vs compressor speed) or in some cases a temperature or wide open throttle switch. Peter ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Why is my ac not working?
The KLIMA Is probably bad -- the signal goes from the PBCU to the KLIMA to the low pressure switch on the receiver/dryer. If the KLIMA relay has burned contact, it won't switch the compressor on no matter what you do as the clutch current goes only through that relay contact set. Check the resistance of the clutch coil as well -- a shorted clutch will simply burn out another KLIMA relay in sort order. Peter Another disagreement I had with the esteemed Herr Doktor. He argued that the Klima never fails. I've had many fail. I've not had a compressor clutch coil fail yet, but I'd never say they don't fail. ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Why is my ac not working?
I've only seen one failed KLIMA so far, but it was in the car where the clutch coil shorted. Burned the internal relay contacts. They can also start to leak and get corroded, but failure is no more common than other failures in MB relays. Peter ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Why is my ac not working?
I checked for cont between the switch and pin 10 of Klima, it was good, pin 1 and ground, it was good, switch and pin 7 I believe of pbu it was good. Pin 13 at pbu is power I believe, if I put positive there and neg pin 7 I show less than a volt, like .6 or something. I even ran a test wire directly from switch to ground, pin 1 of Klima to ground etc thinking it was bad wire also but still no go. Between that and checking ohms on the wires I think the wires are good, there is something I am missing apparently Sent from my iPhone On Jul 13, 2013, at 7:29 PM, Peter Frederick psf...@earthlink.net wrote: The PBCU provides a ground to the voltage signal, so I suspect you don't have voltage at the switch due to a failed wire somewhere between the battery and the pressure switch. I almost forgot -- some engines are equipped with a wide open throttle switch to disconnect the AC compressor at full throttle. If that switch as failed, you won't get AC engagement and no voltage at the PBCU, just as if the low pressure switch was open. I don't know where this switch is in the circuit, but the switch itself is on the throttle linkage. Check for voltage at the pin socket for the KLIMA, this is supplied via the keyswitch. If you don't have voltage at the KLIMA socket for that wire, the AC won't ever come on as the KLIMA relay cannot be energized. You will have to check the KLIMA wiring, I'm not sure if that line is separate or internally connected to the switched positive supply. If you have voltage at the switch but not the connector at the PBCU, you have a wiring failure between the pressure switch and the PBCU or a failed open pressure switch. You can jumper the switch, but you've tried that, right? The system works by the PBCU providing a ground for the relay in the KLIMA, which can be disconnected by an open pressure switch, a failed speed sensor signal (engine speed vs compressor speed) or in some cases a temperature or wide open throttle switch. Peter ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Why is my ac not working?
I had one clutch fail, but have had many klimas fail. This one has me baffled. Sent from my iPhone On Jul 13, 2013, at 8:59 PM, Dieselhead 126die...@gmail.com wrote: The KLIMA Is probably bad -- the signal goes from the PBCU to the KLIMA to the low pressure switch on the receiver/dryer. If the KLIMA relay has burned contact, it won't switch the compressor on no matter what you do as the clutch current goes only through that relay contact set. Check the resistance of the clutch coil as well -- a shorted clutch will simply burn out another KLIMA relay in sort order. Peter Another disagreement I had with the esteemed Herr Doktor. He argued that the Klima never fails. I've had many fail. I've not had a compressor clutch coil fail yet, but I'd never say they don't fail. ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Why is my ac not working?
I was something online about a failed Klima, having a couple of small relays inside the box, remove the cover and clean the contacts. I pulled the cover off this one and I do not see anything that looks like mini relays, it's all computer circuit. Sent from my iPhone On Jul 13, 2013, at 9:36 PM, Peter Frederick psf...@earthlink.net wrote: I've only seen one failed KLIMA so far, but it was in the car where the clutch coil shorted. Burned the internal relay contacts. They can also start to leak and get corroded, but failure is no more common than other failures in MB relays. Peter ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Why is my ac not working?
You might try grounding the low pressure switch wire that goes to the KLIMA with the engine running. This should engage the compressor if the KLIMA is good as the only signal to the KLIMA from the PBCU is a ground. If it does not come on, there is something wrong with the KLIMA or circuit to the clutch. You can also test the clutch itself -- if the coil is OPEN, it won't engage no matter what. Obviously you must have power to the PBCU to get it to operate, but since all it does to operate the compressor is ground the signal wire to the KLIMA, the PBCU unit being dead is like likely that some other failure. Do check the fuse -- you usually get no fan and full heat if it's bad since the monovalve will be open all the time. Peter ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Why is my ac not working?
I will give that a try tomorrow. If it runs I assume it indicates what? The pbu or wire between it and the switch is bad or wire to Klima is bad or what? Sent from my iPhone On Jul 13, 2013, at 10:55 PM, Peter Frederick psf...@earthlink.net wrote: You might try grounding the low pressure switch wire that goes to the KLIMA with the engine running. This should engage the compressor if the KLIMA is good as the only signal to the KLIMA from the PBCU is a ground. If it does not come on, there is something wrong with the KLIMA or circuit to the clutch. You can also test the clutch itself -- if the coil is OPEN, it won't engage no matter what. Obviously you must have power to the PBCU to get it to operate, but since all it does to operate the compressor is ground the signal wire to the KLIMA, the PBCU unit being dead is like likely that some other failure. Do check the fuse -- you usually get no fan and full heat if it's bad since the monovalve will be open all the time. Peter ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
Re: [MBZ] Why is my ac not working?
Ps with the wire jumpers between 5 and 7 at the Klima compressor runs. Sent from my iPhone On Jul 13, 2013, at 10:55 PM, Peter Frederick psf...@earthlink.net wrote: You might try grounding the low pressure switch wire that goes to the KLIMA with the engine running. This should engage the compressor if the KLIMA is good as the only signal to the KLIMA from the PBCU is a ground. If it does not come on, there is something wrong with the KLIMA or circuit to the clutch. You can also test the clutch itself -- if the coil is OPEN, it won't engage no matter what. Obviously you must have power to the PBCU to get it to operate, but since all it does to operate the compressor is ground the signal wire to the KLIMA, the PBCU unit being dead is like likely that some other failure. Do check the fuse -- you usually get no fan and full heat if it's bad since the monovalve will be open all the time. Peter ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com ___ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
