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Hi all, I own a 1999 SL500. Neither my center or floor vents blow any air. Heat and A/C work fine but only come out at defrost and side vents. Any ideas? A vacuum leak? Best place to check, firewall or under dash? Thanks.
twhobie,
Your climate control unit in the dash can be put into diagnostic mode and display stored and real-time errors in your system. Before looking for leaks or
elsewhere at the firewall or dash, etc. run the diagnostics first. Then report back what the diagnostics show and get the specific help you need, if not self evident from the codes displayed.
Try doing a 'advanced search' on the words, climate control diagnostics , in all forums, and you should get the info you need. If not, pm me with your email address and I'll send you a copy I've got that's too large to post here.
Just had it checked today, the M-B mechanic says that the climate control unit needs to be replace. Their parts cost is $995 plus labor. I would like to find a much cheaper ccu. Thanks for asking.
Just had it checked today, the M-B mechanic says that the climate control unit needs to be replace. Their parts cost is $995 plus labor. I would like to find a much cheaper ccu. Thanks for asking.
Did the tech tell you which stored and real time codes came up in the display? If not....ask him. Better yet, have him run the diagnostic program with you watching. Reason....these CCU's can be rebuilt for around $350 and warranteed for a year; they take all of 5 minutes to remove and install. If your tech is telling you $900, there is either more wrong with your system that the tech either hasnt' told you or you haven't told us. If you do nothing else, get a second opinion, and FCS, run the diagnostics.
I spoke with the MB people this morning. They said that no codes tripped when they ran the diagnostics, they removed the ccu, 'reset' it put back- no change.
Said the ccu is bad.
I saw one on ebay for $200 or so.
There are two sets of diagnostics in the CCU that owners can get to without involving the dealer or a tech. 1 set stores error/fault codes in memory, and the other provides real-time values for many of the components in these systems. There are specific diagnostic tests that measure the voltage from the thumb wheels to the left, right, and center vents. If the voltages are out of range, the vents won't work. If you don't know how to get to all this data, pm me with your email address and I'll send the instructions and expected values to you. There are additional tests that can be run via the Star Diagnostics Maintenance Port. Did the tech tell you that's how he got to the diagnostics?
A CCU for $200 on eBay. 2 things, the part number for our car is
202 830 1485; fits '99-'02, and has the latest updates/features. Be careful about the p/n; earlier versions will have a 13 or 12 in the p/n. Confirm w/Mercedes Dealer if the older versions will work. Check the sellers feedback carefully. $200 is way cheap for a solid working unit.
First, a good tech, IMO, would be anxious to tell his customer how he arrived at a conclusion that the CCU is toast and that he wants you to part with nearly $1000 of your money to fix it. I'll shut up about this if you really trust your tech, but from what you've said here, this just doesn't feel right. Once again, though, I'd get a 2nd opinion from a tech or dealer that hooks up your car to the Mercedes Star Diagnostic System to scan the CCU. All dealers have this tool and good independents do too.
Re the part number...perhaps I wasn't clear in the earlier post. The one on ebay has the number 1385 in it, and the one in our cars is 1485, ergo, the ebay part pre-dates your car. IOW, it's the version before our model year although the faceplates/control panels are identical. The question is, 'will an earlier rev level control unit work in your car'? I frankly don't know and would call the dealer to check before buying or get agreement from the seller you can return it if it doesn't operate your CC system exactly like the one that's in there.
I've gotten several private messages about sending out the diagnostic instructions, etc. Rather than that, the links below will take you to another Forum where this topic is discussed at length and the diagnostic test instructions are included. It will help you if you print out the instructions and expected test values pages, and take them with you to the car so you'll have them for reference and can make notes.
Note: When you run the center vents tests (#61-66), remember to turn the thumb wheels open and closed while in diagnostic mode. The readout should go from a low voltage to higher voltage as you turn the wheel from closed to open. This will be clearer when you hands on the unit and run the tests.
Hello Bob: Yes, you were clear on the older parts numbers, I just apparently misread them. I called an M-B parts guy and he said that the #13 CCU part will work fine-so for $84 I bought it.
Okay got the links for the diy diagnostics on the current CCU.
Here they are:
61-2.5
62-4.3
63-4.1 to .9
64-4.1
65-2.3
66-4.3
The dtc info for test#s 226-459 seems to be for pre 1997s. Is there a newer one?
I would like to see if there is an issue with a vacuum line? #423 Y11 on that test.
Steve,
Good find on the CCU, and we all learned, thanks to you, that the older units are compatible. (I would have lost that bet)
LKQ is the 'old' Potomac German company that was aquired awhile back. They have always had an outstanding reputation and you got the deal of the decade for $84.
On your test results...
Tests 61, 63, and 65 (the potentiometer/thumbwheel voltages from high(open) to low (closed) are quite normal.
However, the feedback voltages from the vacuum actuators seems very high. It would lead me to believe that you do have a vacuum problem, as you surmised, at the Y11 vacuum distribution block which if memory serves is located behind the passenger side airbag. The only test that I know of is to get access to the valve block, remove the vacuum lines one at a time and pull vacuum on each line manually. If the vent actuator works when you do this, then the valve block is bad. All this said, I wouldn't jump into this phase until you hook up the new-used CCU and see what happens.
Hopefully others that have had this problem and resolved it can also comment.
Dear Bob and friends.....It's finally over. Found a link on carguru and found the culprit in seconds. Yes! It was one disconnected, thin, white vacuum hose located directly behind the firewall. All vents work now! Bob you were right about the shop. I am disappointed in the Benz crew there (name withheld for now). Either they are crooked, ignorant, or just don't care-or all three.
Hey, anybody want a perfectly good CCU? I put it in yesterday before I found the real problem, and it worked identical to the old one-no floor or center vents working. $100 I will ship it.
Steve
Dear Bob and friends.....It's finally over. Found a link on carguru and found the culprit in seconds. Yes! It was one disconnected, thin, white vacuum hose located directly behind the firewall. All vents work now! Bob you were right about the shop. I am disappointed in the Benz crew there (name withheld for now). Either they are crooked, ignorant, or just don't care-or all three.
Hey, anybody want a perfectly good CCU? I put it in yesterday before I found the real problem, and it worked identical to the old one-no floor or center vents working. $100 I will ship it.
Steve
Steve,
That's great news...congratulations! I'm glad you researched this further as my earlier comment would have had you pulling the passenger airbag for no good reason! Hat's off to you for tracking down the real problem!
About the shop, their original comments just didn't pass the smell test. With a car so rich in diagnostics, for them to say there were no stored codes, etc., was just nonsense.
Since you've now got this service provider's ***** in a vice, I hope you take advantage of this and get something material back from them, i.e., heavily discounted parts, free A & B services for a year, etc. Good luck and have fun!
Dear Bob and friends.....It's finally over. Found a link on carguru and found the culprit in seconds. Yes! It was one disconnected, thin, white vacuum hose located directly behind the firewall. All vents work now! Bob you were right about the shop. I am disappointed in the Benz crew there (name withheld for now). Either they are crooked, ignorant, or just don't care-or all three.
Hey, anybody want a perfectly good CCU? I put it in yesterday before I found the real problem, and it worked identical to the old one-no floor or center vents working. $100 I will ship it.
Steve
Resurrecting an old thread. I am experiencing similar lack of air from the center vents with identical readouts for test points 62 and 66 with a reading of 4.2 mv. Can you point me to where you found the disconnected hose? Was it the one going to the distribution block on the fire wall? I just changed this out as I found a crack on the bottom with out any changes in operation.
Thank you for your help.
Ron
Resurrecting an old thread. I am experiencing similar lack of air from the center vents with identical readouts for test points 62 and 66 with a reading of 4.2 mv. Can you point me to where you found the disconnected hose? Was it the one going to the distribution block on the fire wall? I just changed this out as I found a crack on the bottom with out any changes in operation.
Thank you for your help.
Ron
I found the hose, rear of engine. It was disconnected. Thanks everyone for this wonderful thread.
Well similar problem here. Center and side vents just stopped working. In the control panel, the forward arrow is also no longer lighting up as an option when going through the zones. It just goes goes from lower to upper and skips mid.
Checked for a vacuum line as in the pics above and could not find it in my 600. Was hoping that would do the trick. The control panel screen would occasionally go bad which required me to press on it to fix, so I have a new unit on the way anyway. If that doesn't work, I'll dig around for that line. Is it located somewhere else in the 600s or should I look closer?
Well similar problem here. Center and side vents just stopped working. In the control panel, the forward arrow is also no longer lighting up as an option when going through the zones. It just goes goes from lower to upper and skips mid.
Checked for a vacuum line as in the pics above and could not find it in my 600. Was hoping that would do the trick. The control panel screen would occasionally go bad which required me to press on it to fix, so I have a new unit on the way anyway. If that doesn't work, I'll dig around for that line. Is it located somewhere else in the 600s or should I look closer?
Thanks
the vacuum block and lines that can cause issue with ac vents on 600s is in the right upper side of engine bay by the diagnostic port, but have you pressed the red or blue buttons above the center vents first? you have to do that to be able to get center vents flowing
the vacuum block and lines that can cause issue with ac vents on 600s is in the right upper side of engine bay by the diagnostic port, but have you pressed the red or blue buttons above the center vents first? you have to do that to be able to get center vents flowing
Thank you. Yes, tried pressing and holding and every combination of the two. Neither red or blue buttons light up.
11-11-2010, 07:15 PM
