If you recall last week, we almost had it all diagnosed out and ready to fix...but still no cold air yet!! (well..sometimes its still cold.. lol)
My problem was the A/C would work SOME of the time, but not all of the time.
A few of you helped me out, and we thought it may be the A/C speed sensor on the back of the compressor.
I was able to get the part, and then I brought it to a local MB specialist. (had never met this guy)
He took the car in, looked at it, and told me that it was not the a/c speed sensor that needed replaced but instead the entire compressor...
He claimed that the compressor had a "wabble" in it, causing it to send a signal to the speed sensor to shut it off.
Basically he was saying my speed sensor was fine. And the compressor needed replaced.
He quoted me 1600$ US for the job....Claiming that most of the expense was in the parts.
So I called the guy who got me the speed sensor and he was willing to sell me a remanufactured A/C unit with a year warranty for a mere 250$!!
Excitedly, I called the repair shop, and told them I had found the part myself, and how much would he charge for the labor...?
His response both startled and shocked me at the same time....
" Well, we were going to make money on both the parts and labor....so if you bring in the part...Ill have to charge you more than our standard labor rate...Ill have to charge you 1.5x the amount we normally charge for labor..."
WHAT!??
Ok, I know thats insane, and i'm not going to let someone take me to the cleaners just because he couldn't rip me off the first time...
Anyways.....
I called my local a/c repair shop, and explained the entire situation to him.
His first reaction (besides disgust at the other guys labor rate ) was :
."How the hell could the guy know the a/c had a wabble unless he had x-ray vision ?? "
He claimed it was impossible to see in side a compressor even in a MB and that there was no way the man could have known that without doing more extensive work.
He then called his a/c rebuilder, who claims to know MB well. And this gentleman, thinks its the actual control unit (at the dash)
He asked if the a/c will work if I shut the car off and back on (maybe a few tries) but that I have to turn the car off to get it to work.
That does work sometimes, so I answered "yes".
He said that is what makes him believe its the a/c control unit, nothing wrong with the speed sensor, or the actual compressor....
So NOW, I'm turning back to you all, my friends, my comrades, and my fellow enthusiasts to help me settle this matter...
Is it the whole compressor I need replaced??
Or is this a/c guy correct in his assumption that it is the control unit ??
Either way, I am going to have to shell out a few bucks for this, and I don't have the money to guess wrong unfortunately....
ANY help or insight into either the control unit, or the compressor would be GREATLY appreciated!!!!
The a/c guy just called me back, and alerted me that his rebuilder would like to take it apart (the compressor) and see if it needs rebuilt, or if it is just the speed sensor..
I guess now he did a little more research on his own, and he must be leaning away from the "control unit" theory....
LOL what a mess!!!
I only wish I had one of them damn a/c machines and knew what I was doing!
unfortunatley, I have a hard time even changing the oil...that alone turns into a fiasco with me everytime
Im still looking for anyones input into wat I should do for this problem.
I think I replied to your thread about this. My A/C system had it share of breakdowns due to age. First that I had to replace was the 'evaporator sensor', located behind the dash and of course connected to the evaporator, this was about 18 months ago. Symptom=compressor not coming-on at all.
Next to go was the 'speed sensor' on the compressor, this was replaced about a month ago. Symptom=compressor comes-on for a few minutes then shuts-off completely. Restart the car and it does the same thing.
At both instance, the control unit was never a suspect. As long as your climate control is working (on auto mode) then it's fine.
A rebuilt compressor with 1 year warranty is a good deal because they'll replace most parts with brand new ones. But if the compression of your compressor is still good, why change it or why have it rebuilt at all?
Change the speed sensor first, that's cheaper
By they way, were you able to test a different Klima relay on your car?
Please refresh us one more time about your problem.
Whether it is the control unit cutting the compressor off or the compressor itself is not working should be easily testable. There should be no possibility of an error to distinguish these possibilities. You do not need to take the a/c system apart to do this test. There is just one wire that brings in the voltage to run the compressor clutch. Turn the a/c on in the car and check the voltage on this wire, if you get battery voltage there and the compressor does not run, then it is the compressor clutch that is bad. Also if this is the case, you still dont have to replace the whole compressor, just the clutch can be replaced, and in some MB cars you dont even have to remove the compressor to do this. Alternatively, you can disconnect the connector on the compressor and apply battery voltage to the clucth coil terminal and determine if the compressor will engage and give you cold air. When doing this, make sure you apply the battery voltage to the clutch coil terminal and not the speed sensor terminal.
These two tests can tell you a lot about your a/c system.
If you dont get any voltage on the compressor terminal when you turn on the a/c, the first thing you have to look for is a controller module called the base module and the pressure switch on the drier.
The compressor connector is a 3 pin connector. Pins 1 and 2 are speed sensor terminals and Pin 3 is the compressor clutch terminal. The coil is grounded via the chasis. The color coes on the wire are:
Red/Blue is pin 1, White/Blue is pin 2 and Blue/Green is pin 3. The wire connected to pin 3 should most likely also be the thickest wire.
I would take the car to an auto air specialist (not the ones you have visited so far, I am not sure they are working in your best interest), ones that only do auto air and get a diagnosis. It could also be that you dont have sufficient refrigerant charge. Or take it to an auto parts store and see if anyone there could help you check the compressor, tell him that you know the pin configuration and just want to check if the compressor engages with external voltage.
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