2009 ML320. A/C started getting warmer as the engine warmed up.Both high and low pressure checked good with A/C running, but with a/c off the low pressure side will climb up to about 80psi and high side drops to about 100. I replaced the expansion valve and now the system holds at about 68 to 70 degrees at the vent, but no cooler. Pressure switch seems to be working fine - unplugged it's like the a/c is turned off - plug it back in and the pressures go back to about 50 low / 250 high with outside temps around 90. Need to check cabin filters but they're almost new (3 months at most). I'm wondering about blend door problems? thermostats? sensors? etc. 170k miles on the car and probably the original compressor / condenser / receiver dryer.. Any ideas?
A/C @ 70 degrees
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Withe pressures 50/250 lines going to the expansion valve should have significant temperature difference. Large one ice cold, small on warm/hot.
Need to get a scanner that will read codes and display actual values like compressor demand and all temp sensors.
I have an iCarsoft MBII, which is pretty lame, but it didn't show any codes under the A/C module. Not sure if it reads out any other pertinent data - I'll have to check it out.
There is a temp difference between the lines - before changing the expansion valve it would gradually equalize and quit blowing cold. Now there is a consistent temp difference, but just not as much as it should be. I'll take my laser thermometer to them and see what the actual temps are and post them. Wife drove the car yesterday in 95+ outside temps and it consistently blew out 70 degree air from the vents over a 15 mile drive....which is good, but not good enough.
There is a temp difference between the lines - before changing the expansion valve it would gradually equalize and quit blowing cold. Now there is a consistent temp difference, but just not as much as it should be. I'll take my laser thermometer to them and see what the actual temps are and post them. Wife drove the car yesterday in 95+ outside temps and it consistently blew out 70 degree air from the vents over a 15 mile drive....which is good, but not good enough.
Turns out the iCarsoft MBII has some good data readouts for the A/C module! Compressor demand and actual temps and pressures are really good indicators of what is going on in the system. My compressor demand was staying pegged on 100% but the temps at the evaporator were 70F or so. Pressure readings were consistent with what I was getting on my manifold set. I took a gamble and bought a kit from Amazon including: compressor, condenser, dryer, expansion valve (which I had already replaced), gaskets and 8 oz. of pag 46....all Asian made (UAC brand) but I had good results with that brand on my Ford truck. Total kit price: $370. The work was not easy, especially since there are NO videos for this service on YouTube....I really doubt that many people actually work on these cars themselves, but the alternative was to pay a shop or dealer $2 to $4,000 to do this for me which I cannot afford. I got the parts replaced over about a 5 day period (details can be provided if anyone is interested. I'm not in the video making business although someone needs to be!) The biggest problem I had was that the electrical connector on the compressor would not plug in even though it looked identical. I ended up having to remove the compressor (again) and re-wire it myself with a simple connector kit I had bought from Amazon. I charged the system finally and immediately started getting 45 degree air from the vents! We ran it non-stop on a recent vacation with no issues whatsoever. It's cool to be cool again. ;0). iCarsoft readings with dash temps set at 74F and 95F outside temps are: refrigerant pressure - about 14 bar; evaporator temp - about 35F; compressor demand - about 50 to 99% depending on the situation. I cursed the stupid plastic - snap together design of the radiator / condensor / intercooler while trying to figure out how to get it apart.....C'mon MB! a few screws would do the same job as all the ridiculous injection molded snaps and tabs that hold this thing together! What takes 10 minutes to remove on a Ford F-350 took me 3 days on this engine - I am thoroughly convinced that this is BY DESIGN to keep anyone (like me) from actually working on their own car....disgusting. I refuse to buy into the notion that "only dealers can do that service!" I've worked at stealerships in the past and I've seen the games they play. Again....disgusting! I've proved over and over again that you CAN work on these cars if you are determined enough (and don't have the thousands of dollars to throw away to have someone do it for you.) My next job will be to do away with the absolutely idiotic transmission oil level design on this engine - hey, it's maintenance free, right? NO, it's just STUPID....no dipstick, no way to check the level, you have to fill it FROM THE BOTTOM....ugh, I'll be fixing that next with no help from MB, thank you very much. I'll post the details here when I get it done.
CURRENT: 2011 SL550 FORMER: C300, ML350, CLK550 Cabriolet, C240, ML320, 300TD
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First of all, long posts are easier to read in paragraphs! 
There is a hug difference between the size of the engine bay in a full-frame F350 and a car-based SUV. There will always be challenges in accessing some parts.
My guess is that one of those parts you replace was bad, probably either the dryer or expansion valve. I am glad you have it fixed now.
As for the transmission fill and level check being done from underneath, this is is becoming more and more common on all cars. It's really not that difficult to do this job, just slightly more complex.
There is a hug difference between the size of the engine bay in a full-frame F350 and a car-based SUV. There will always be challenges in accessing some parts.
My guess is that one of those parts you replace was bad, probably either the dryer or expansion valve. I am glad you have it fixed now.
As for the transmission fill and level check being done from underneath, this is is becoming more and more common on all cars. It's really not that difficult to do this job, just slightly more complex.
@rudney:
Apparently, you haven't removed an F-350 A/C compressor! lol. WAY more difficult than the ML320....not to mention cylinder head removal and so on.
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I just hate when manufacturers actually TRY to make things difficult to work on without need. It used to be that those things happened by chance due to....say, a lower hood design, or aerodynamics.....but it has become more and more apparent that these difficulties are BY DESIGN rather than by chance.
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I saw, back when I worked at a Mercedes stealership, some of the ludicrous service requirements that MB called for....and was even more shocked to see how all the American manufacturers were following suit and doing the same stupid things. So, just because "everyone else is doing it" doesn't make it right.
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I have worked as a moldmaker in injection molding and I can assure you that a HUGE amount of money was spent to create the "snap together" design of the heat exchangers on the front of the ML320, when the same thing could have been accomplished with a few $0.10 screws. THAT is why the cars cost 50k or more these days.....and then they redesign the whole thing every year or two, whether it needs it or not. Why was the VW bug a huge success? Because they didn't change everything all the time. If it ain't broke, don't fix it!
I'm glad I've got it fixed too, but I'm sure that every time I service this car it will be met with similar aggravations, when I see how hard MB has worked to make their cars un-workable.
Apparently, you haven't removed an F-350 A/C compressor! lol. WAY more difficult than the ML320....not to mention cylinder head removal and so on.
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I just hate when manufacturers actually TRY to make things difficult to work on without need. It used to be that those things happened by chance due to....say, a lower hood design, or aerodynamics.....but it has become more and more apparent that these difficulties are BY DESIGN rather than by chance.
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I saw, back when I worked at a Mercedes stealership, some of the ludicrous service requirements that MB called for....and was even more shocked to see how all the American manufacturers were following suit and doing the same stupid things. So, just because "everyone else is doing it" doesn't make it right.
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I have worked as a moldmaker in injection molding and I can assure you that a HUGE amount of money was spent to create the "snap together" design of the heat exchangers on the front of the ML320, when the same thing could have been accomplished with a few $0.10 screws. THAT is why the cars cost 50k or more these days.....and then they redesign the whole thing every year or two, whether it needs it or not. Why was the VW bug a huge success? Because they didn't change everything all the time. If it ain't broke, don't fix it!
I'm glad I've got it fixed too, but I'm sure that every time I service this car it will be met with similar aggravations, when I see how hard MB has worked to make their cars un-workable.
CURRENT: 2011 SL550 FORMER: C300, ML350, CLK550 Cabriolet, C240, ML320, 300TD
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I must be used to it because I find MBZ vehicles to be easy to work on. Much easier than the typical FWD setup with transverse-mounted engines. As always, there are things that are difficult, but I find that on any car. The worst cars I've every worked on are minivans. They stuff the engine half under the windshield. My daughter had a Ford Windstar and it was a nightmare to do anything - except the alternator. It was on the top of the engine in the front. It was a good thing because the thing died every 6 months!
Keep in mind that some of the things auto manufacturers have been doing are related to the CAFE 2025 standards which (thankfully) have been tossed out. Remember that legislation where every manufacturer's Corporate Average Fuel Economy had to be 54.5mpg? Of course no one was going to get close because even hypermiling a Prius with the rear seats removed won't hardly make 54.5mpg, much less all these SUVs and pickup trucks consumers are buying. But that's OK, because the legislation called for "credits" that manufacturers would get for "trying real hard". For example, while reducing a model's weight by 5% may not actually save much fuel, it would get a 5+ mpg "credit". So manufacturers jumped on the weight-reduction bandwagon, and that's why you see cars without spare tires, without dipsticks, and with plastic moldings where bolts or screws used to be.
MBZ used to not care. They's just use bigger engines to carry heavier cars and add that "gas guzzler tax" on the window sticker. But CAFE 2025 made it so manufacturers could not pass the fines onto the consumer, so thy all, including MBZ, did things. Oh, some other things that earn credits: auto-stop engines that shut off instead of idling, LED lighting, shutters on the intake to make the vehicle more aerodynamic, and low-rolling-resistance tires. Add it all up and a 25mpg SUV can earn enough credits to get darn close to the 54.5mpg mandate.
Keep in mind that some of the things auto manufacturers have been doing are related to the CAFE 2025 standards which (thankfully) have been tossed out. Remember that legislation where every manufacturer's Corporate Average Fuel Economy had to be 54.5mpg? Of course no one was going to get close because even hypermiling a Prius with the rear seats removed won't hardly make 54.5mpg, much less all these SUVs and pickup trucks consumers are buying. But that's OK, because the legislation called for "credits" that manufacturers would get for "trying real hard". For example, while reducing a model's weight by 5% may not actually save much fuel, it would get a 5+ mpg "credit". So manufacturers jumped on the weight-reduction bandwagon, and that's why you see cars without spare tires, without dipsticks, and with plastic moldings where bolts or screws used to be.
MBZ used to not care. They's just use bigger engines to carry heavier cars and add that "gas guzzler tax" on the window sticker. But CAFE 2025 made it so manufacturers could not pass the fines onto the consumer, so thy all, including MBZ, did things. Oh, some other things that earn credits: auto-stop engines that shut off instead of idling, LED lighting, shutters on the intake to make the vehicle more aerodynamic, and low-rolling-resistance tires. Add it all up and a 25mpg SUV can earn enough credits to get darn close to the 54.5mpg mandate.
2008 ML350 (Me!), 2018 GLC300 (Wife), 2010 GLK350 (sold), 2003 ML-350 (Totaled!)
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It's a bit of a stretch to say these difficulties are all "by design". I seriously doubt the engineers sat down and said "OK, let's try and design this to be as difficult as possible. After all, we gotta screw the DIY guy!". I would bet $20 that people said the same thing about Philips head screws and disc brakes back in the day. "Why did they change it? It was working fine as is! It's all a plot to get us to go to the dealer or buy new tools!"
The removal of the dipstick was most likely a cost saving/business decision, just like removing the drain plug on torque converters. The shop does all their tranny work with a flush-fill machine anyway, and while it may seem like they are being penny-wise / pound foolish, those little parts all add up. They can save a ton of money over hundreds of thousands of vehicles by deleting those parts
Speaking of which, it would not surprise me one bit to see oil pan drain plugs disappear one day as well. Every dealer does oil changes top-side now, and many DIY'ers do as well. It's all about efficiencies at scale.
The removal of the dipstick was most likely a cost saving/business decision, just like removing the drain plug on torque converters. The shop does all their tranny work with a flush-fill machine anyway, and while it may seem like they are being penny-wise / pound foolish, those little parts all add up. They can save a ton of money over hundreds of thousands of vehicles by deleting those parts
Speaking of which, it would not surprise me one bit to see oil pan drain plugs disappear one day as well. Every dealer does oil changes top-side now, and many DIY'ers do as well. It's all about efficiencies at scale.
Are there any service books or online manuals for these cars? All I've found for MB seems to stop about 2006 (another reason why it seems obvious to me they don't want you working on these cars!)
Every engineering decision is a compromise: any machine can be designed to last a lifetime (or longer!), but there are always trade-offs in cost. Henry Ford used to send engineers to junk yards to find out which parts were still good on his worn out cars, so he could make those parts cheaper. That's just business, I guess. I would rather he'd of made the worn out parts better, instead of making the good parts worse, but that's just me.
I've been in engineering meetings where decisions like this are made, so don't think that I'm being conspiratorial when I say that MB's designs are intentionally made to discourage tinkerers. It may be a secondary issue, but it IS an issue.
I truly believe that even with the exorbitant cost of vehicles these days (due to the constant redesign of things that don't need to be redesigned) is secondary to the manufacturers, to the profits made from a lifetime of servicing these vehicles. Hence, more and more computer controls that cannot be overridden by the DIYer, leaving him with no choice but to Pay the Piper.
I'm just one of those stubborn ones who thinks that, not only are the service costs ridiculous, but if I can do it myself I should, and it will probably be done better! Then there is the "trust factor." I've seen it many times, and EVERYBODY has stories about it: extremely bad service centers who messed up their cars...and then made THEM pay to fix it. It happens all the time....and that's not just at the greasy shop on the corner, but at the dealerships who are supposed to be the experts and do everything right. Believe me, I've worked at some of those dealerships and have seen it first hand - and that's why I don't work there anymore. When I work on my car I know exactly how much care was taken and how thoroughly the job was done - I don't think you EVER have that assurance at a dealership...no matter how nice their floormats and keyfobs are.
I think it's way overdue for a modern day rerun of the original VW bug legacy....make a car simple, safe, reliable, and easy to work on, then LEAVE IT ALONE FOR YEARS!!! and watch the profits pile up. I would think Asia would be all over it. I for one, don't need a new dashboard design in the showroom every year - who buys a new car every year anyway? I'm 61 and haven't bought my first one yet....and don't plan to, unless someone finally gets some sense in the auto industry.
Thanks for letting me rave, lol.
Every engineering decision is a compromise: any machine can be designed to last a lifetime (or longer!), but there are always trade-offs in cost. Henry Ford used to send engineers to junk yards to find out which parts were still good on his worn out cars, so he could make those parts cheaper. That's just business, I guess. I would rather he'd of made the worn out parts better, instead of making the good parts worse, but that's just me.
I've been in engineering meetings where decisions like this are made, so don't think that I'm being conspiratorial when I say that MB's designs are intentionally made to discourage tinkerers. It may be a secondary issue, but it IS an issue.
I truly believe that even with the exorbitant cost of vehicles these days (due to the constant redesign of things that don't need to be redesigned) is secondary to the manufacturers, to the profits made from a lifetime of servicing these vehicles. Hence, more and more computer controls that cannot be overridden by the DIYer, leaving him with no choice but to Pay the Piper.
I'm just one of those stubborn ones who thinks that, not only are the service costs ridiculous, but if I can do it myself I should, and it will probably be done better! Then there is the "trust factor." I've seen it many times, and EVERYBODY has stories about it: extremely bad service centers who messed up their cars...and then made THEM pay to fix it. It happens all the time....and that's not just at the greasy shop on the corner, but at the dealerships who are supposed to be the experts and do everything right. Believe me, I've worked at some of those dealerships and have seen it first hand - and that's why I don't work there anymore. When I work on my car I know exactly how much care was taken and how thoroughly the job was done - I don't think you EVER have that assurance at a dealership...no matter how nice their floormats and keyfobs are.
I think it's way overdue for a modern day rerun of the original VW bug legacy....make a car simple, safe, reliable, and easy to work on, then LEAVE IT ALONE FOR YEARS!!! and watch the profits pile up. I would think Asia would be all over it. I for one, don't need a new dashboard design in the showroom every year - who buys a new car every year anyway? I'm 61 and haven't bought my first one yet....and don't plan to, unless someone finally gets some sense in the auto industry.
Thanks for letting me rave, lol.
CURRENT: 2011 SL550 FORMER: C300, ML350, CLK550 Cabriolet, C240, ML320, 300TD
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If you are serious about DIY, get your own SDS setup. You can buy a turnkey Chinese clone system for around $500, or bring your own laptop and buy the multiplexer with software for under $300. It includes WIS (Workstation Information System) which is the official shop manual the dealer uses. You can also buy a strand-alone copy of WIS on eBay for around $30. It covers all MBZ cars.
Regarding the economics of the injection molded tab mounting, they just look at it like this:
$250,000 mold tool / 500,000 vehicles = $0.50 per car. If it saves a minute of labor on the line, which these days could be $40/hour/60 min/hour = $0.67 per car. End of analysis.
Plus it was probably proposed by the same vendor who makes the part for “insert generic cheap-ass car here”, which saves them on design costs.
$250,000 mold tool / 500,000 vehicles = $0.50 per car. If it saves a minute of labor on the line, which these days could be $40/hour/60 min/hour = $0.67 per car. End of analysis.
Plus it was probably proposed by the same vendor who makes the part for “insert generic cheap-ass car here”, which saves them on design costs.
The trans fill idea is idiotic. Why not make it a fill plug instead of a drain. You have to drop the pan anyway, that drains it. Could always suck it out if that was a problem.
The design problem with MB and most German cars is two fold. First the cars are designed by people who don’t work on their own cars in a culture that supports disposable cars. Second is they are too proud to admit design problems and make revisions. They redesign the wheel over and over. Each time addressing a past issue but introducing a new one.
The design problem with MB and most German cars is two fold. First the cars are designed by people who don’t work on their own cars in a culture that supports disposable cars. Second is they are too proud to admit design problems and make revisions. They redesign the wheel over and over. Each time addressing a past issue but introducing a new one.
CURRENT: 2011 SL550 FORMER: C300, ML350, CLK550 Cabriolet, C240, ML320, 300TD
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The trans fill issue is again, not an MBZ issue. It's like that on most all modern cars. It makes packaging easier with not having to route a diptube and again, it saves weight. Although the eight saved is not much, it still goes toward the CAFE credits.
Honestly, I find MBZ cars fairly easy to work on. Not everything is easy on every car, but overall, I find them easier to maintain and repair than most American and Asian brands. Don't compare this to working on your 1965 Mustang or 1969 Chevelle. Compare it to a Lexus RX or Nissan Murano.
Honestly, I find MBZ cars fairly easy to work on. Not everything is easy on every car, but overall, I find them easier to maintain and repair than most American and Asian brands. Don't compare this to working on your 1965 Mustang or 1969 Chevelle. Compare it to a Lexus RX or Nissan Murano.
...OR....let's use existing sheet metal bending equipment we ALREADY have and NOT spend a quarter mil on a new mold and save our customers $500 a piece. Those are the economics that make sense. Think about it.
So you would only have 500 customers?
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