Tech Q&A

Richard Simonds

Erratic air conditioner, Part II

Q: Now that we're driving our 2005 C55 AMG in hot weather, we've noticed that the air conditioning doesn't always seem to work when we turn it on, especially if the car has been sitting out in the heat. We're guessing that there is a sensor in the system that prevents the a/c from working when the engine is running hot. Are we correct, or is it possible there's something wrong with the cooling system?

A: Check the Freon (R-12 or R134a) level for a full charge when the a/c does not cool.  There are many possible issues, but a trained tech with access to a Star Diagnostic Scanner should be able to diagnose the problem. Member’s response: When we had our annual B-Service today, we had the service department check the HVAC system. As was suspected, we were low on Freon –by 50 percent (one pound instead of the two pounds that should have been there). They believe that may have been the cause of the isntermittent failure of the regulator and motor, which are now being replaced.

A good engine degreaser

Q: What’s a good engine degreaser that does not have a petroleum base like GUNK – GUNK works really well but it leaves that lasting petroleum smell on the engine and in the vehicle. I would prefer anything that would be environmentally friendly and still a good engine cleanser, even it’s considered a milder product, as long as it didn’t leave a strong odor afterward.

A: We talked to several MBCA members who are known for the quality of their concours-prepped cars, There are several products in the ZEP family of de-greasers and they come highly recommended by detailing fanatics. The one most suitable for all-around automotive use is ZEP Industrial Purple Solvent Degreaser (13 oz. can #1049848).  If you find it works well for you and want to buy it in bulk, a related product is ZEP Industrial Purple Cleaner and Degreaser Concentrate (1 gal. and 5 gal bottles #ZU0856128). For more information and to learn about applications and ingredients you can visit their website at www.zep.com/products/home/degreasers.

Discontinued paint color

Q: Is Mercedes-Benz paint code 989 Desert Taupe discontinued? If it is, what substitute color would you suggest for a repaint?

A: There are a couple of ways you can find the color you want: (1) Contact the Mercedes-Benz Classic Center in Irvine, California, to determine whether the paint was discontinued and if there is a  formula for the paint (866.622.5277); or (2) Go to an MBUSA-authorized Collision Center that has access to all the paint formulations; they can use a paint-color reader to re-create the formula and provide you with a top-quality paint job.

Transmission problems

Q: I put about 5,000 miles a year on my 2003 W210 wagon with 87,000 miles. A few years ago, I had transmission problems and replaced the conductor plate and connector, using all M-B parts; it ran great. Last night I had to stop short and then turn; the transmission did not engage. I shut the engine off and then back on. The car went into limp-home mode and malfunctioned again. With my foot off the gas, the car accelerated. When I pressed the gas pedal, the transmission disengaged again and the check engine light came on. My mechanic thinks the engine was sending a bad message to the transmission. Anyone got any ideas?

A: You need to either go to a Mercedes-Benz dealership or to an independent Mercedes shop that subscribes to the Star Diagnostic System. The SDS can identify the fault code(s) and suggest remedies for the service people to use to repair your W210 E-Class Wagon. It certainly is not safe to drive as it is.

Pairing garage door opener

Q: We’ve just bought a used 2014 Mercedes-Benz and noticed that it has three buttons near the rear-view mirror that I believe are intended to actuate a remote garage door opener (the owner’s manual is long gone). Is there a common set of steps that would pair our car’s buttons with our garage door opener?

A: This isn’t hard to do, but even the newest owner’s manuals are a bit short on instructions. If you have an older garage door apparatus, it’s very straightforward, but if you have a newer “rolling-code” system that resets the code with each use, there’s an additional step that isn’t obvious. This takes a few extra minutes and a stepladder to carry out.

1. First clear all old codes from your car by turning on the ignition; press and hold all three buttons simultaneously for about 20 seconds.

2. With your remote garage-door switch near the three buttons in the car, press and hold the button in the car you want to pair with the opener until the indicator light turns yellow and begins to flash. 3. Press the button on the garage door opener and hold it until the yellow light turns green or starts flashing green. It may take up to 30 seconds for the Homelink system in the car to recognize your garage door code.

3. If the light turns red, repeat steps 1-3, holding the opener at a different angle, until you get a green light. If the light shows steady green, then you have an old fixed-code system; your car switch is now paired and will operate the garage door. If the light is flashing green, then you have a rolling-code system and you will need to sync the car’s system with the actual garage door mechanism rather than just the remote switch.

In this case, you’ll need to move the car out onto the driveway (but still near the garage) and get a stepladder: You’ll need to press a button on the opening motor mechanism as part of the pairing process.

Climb the ladder and check the back of the mechanism for a button.  It might be labeled a “Smart Button,” or “Training Button,” or have no label at all, but it will be fairly obvious. Make a mental note of where it is. Back in the car, turn the ignition on, and repeat steps 1-3. Once the green light is flashing, you have about 30 seconds to climb back up the ladder and push that button, and then get back to the car to push the opener button. Push the button and hold it for about five seconds, then release for five seconds. Keep on pushing (it usually takes three to four tries) until the door to the garage closes. Congratulations! You have now mated your rolling-code remote garage door opener with the button installed in your car. Keep in mind the technology did change about 10 years ago, so earlier models may not be able to be paired with current door systems.