Mercedes SLK World banner

1 - 11 of 11 Posts

·
Registered
Joined
·
17 Posts
Discussion Starter #1
I have an issue with the AC. It stopped working about a month ago. Have been running through all of the forum to find issues. All the fuses are good. New capacitors installed in SAM. Duo valves checked. I car scanner shows voltage everywhere it should be. Pressure was never low on refrigerant. Checked that first. 3 weeks to get into dealer. No Indy’s in southern Illinois I can find. On a side note have aftermarket Cree headlights installed. Worked for over a year until I repaired the SAM and now passenger low beam light is out. I have 12 VDC AT PLUG.
 

·
Registered
Joined
·
2,175 Posts
Can’t tell. Have not been under car yet to check voltage at the compressor. The car scanner shows 100% demand but getting under car in the garage is a bit tough.
Reading at the compresor is a PWM signal. A volt meter only reads averages and is slow so you will need a scope. Have all the fault codes been cleared from the A/C system? If not the sytem will not operate.

Did you replace the capacitors in the front SAM or did you have someone do it for you? Are you sure the polarity on each was set correct?
 

·
Registered
Joined
·
17 Posts
Discussion Starter #7
Can’t tell. Have not been under car yet to check voltage at the compressor. The car scanner shows 100% demand but getting under car in the garage is a bit tough.
Reading at the compresor is a PWM signal. A volt meter only reads averages and is slow so you will need a scope. Have all the fault codes been cleared from the A/C system? If not the sytem will not operate.

Did you replace the capacitors in the front SAM or did you have someone do it for you? Are you sure the polarity on each was set correct?
I am now in contact with @i860 an he is going to help me become a proud STAR owner. I have 2 permanent stored codes. One for coolant not at expected temp. Thermostat is sitting on work bench and ready for me to get some time free. Appears stuck open and doesn’t reach temp quick enough. The other is evaporative cooler that may be causing my problem but I have no local MB dealer and no one close to me has a STAR system (maybe a side job for me if I can get proficient) so I am waiting to get that cleared and check the compressor. All other indications as far as demand signals look good according to iCar scanner. The headlight issue is driving me crazy though. I have 12.4 vdc at the plug and neither the old OEM light or the new Cree light will illuminate.
 

·
Registered
Joined
·
2,175 Posts
I am now in contact with @i860 an he is going to help me become a proud STAR owner. I have 2 permanent stored codes. One for coolant not at expected temp. Thermostat is sitting on work bench and ready for me to get some time free. Appears stuck open and doesn’t reach temp quick enough. The other is evaporative cooler that may be causing my problem but I have no local MB dealer and no one close to me has a STAR system (maybe a side job for me if I can get proficient) so I am waiting to get that cleared and check the compressor. All other indications as far as demand signals look good according to iCar scanner. The headlight issue is driving me crazy though. I have 12.4 vdc at the plug and neither the old OEM light or the new Cree light will illuminate.
Yes, it does sound like you need to get the codes cleared. Get that done and see what you have then.
 

·
Registered
Joined
·
484 Posts
The headlight issue is driving me crazy though. I have 12.4 vdc at the plug and neither the old OEM light or the new Cree light will illuminate.

Did you measure the voltage with the bulb connected?

If the voltage is there when bulb is connected, then either bulb is faulty, or connector is faulty


Did you measure the voltage at the bulb holder +ve and -Ve or did you use a body earth?
There could be an earth fault to the bulb connector
 

·
Registered
Joined
·
17 Posts
Discussion Starter #10
The headlight issue is driving me crazy though. I have 12.4 vdc at the plug and neither the old OEM light or the new Cree light will illuminate.

Did you measure the voltage with the bulb connected?

If the voltage is there when bulb is connected, then either bulb is faulty, or connector is faulty


Did you measure the voltage at the bulb holder +ve and -Ve or did you use a body earth?
There could be an earth fault to the bulb connector
I tested to both the ground on the fender well and the to the brown plug wire. 12vdc for both tests. When I plug in the LED assembly is plugged in it drops to below 1. The assembly is new and when I switch the whole assembly the fault stays on the passenger side. The lights worked for over a year before this issue.
 

·
Registered
Joined
·
484 Posts
If the voltage drops when you insert the LED bulb, then you have an issue with current flow.


Have you checked it with a regular bulb.


It is possible the SAM does not like the LED load and limits the current.


However if this worked before, then could be a fault inside the SAM, or with wiring or wiring connections.


Can you do the same test, measuring voltage at the SAM?




I have seen a similar issue on my MGTF.



It was caused by an unusual fuse! The fuse had a very small bulb in parrallel to the fuse element. The idea was when the fuse is OK, the bulb is shorted out. When the fuse blows open, the bulb is now in series with the load, and will illuminate, indicating a blown fuse. The bulb acts as a current limiter to a few mA


https://www.autoelectricsupplies.co.uk/product/854/category/157

When measuring the voltage at the bulb holder with no bulb I got 12V, but 0V when a bulb was connected. Measuring the fuse gave about 30 ohms across it.
Never seen these fuses before, or since.
Just a possibility
 
1 - 11 of 11 Posts
Top