A/C recommendations for the MB vehicles - Page 30 - PeachParts Mercedes-Benz Forum

Squiggle Dog · #**436** 06-25-2018, 07:28 PM

For those interested, at the advice of the "stay with R-12" crowd, I called around to almost every shop in the Phoenix, Arizona valley that does automotive air conditioning. They said they haven't used it for years, can't get it, don't have the equipment, and said it would be nearly impossible to find. Even the ones that advertise that they use R-12 on their websites said they sold their equipment. Their advice was "just buy some adapter fittings and we can put in R-134a".

I did find a shop in Tucson that will charge with R-12, so I might be making a five hour round trip if I decided to stay with R-12. I'd rather NOT have my air conditioning blowing warm in stop and go traffic, which is what I'd expect out of R-134a, even though I replaced every component of the air conditioning system, including a 16" auxiliary fan, parallel-flow condenser, Sanden compressor, hoses, evaporator, expansion valve, etc. Keep in mind that we have 120F summers here. It was 112 just a few days ago.

Anyway, as nice as sticking with R-12 sounds, it seems very difficult to find a place that will charge with it--even if you brought them the bottles they still won't touch it.

ROLLGUY · #**437** 06-25-2018, 10:35 PM

Quote:

Originally Posted by Squiggle Dog

For those interested, at the advice of the "stay with R-12" crowd, I called around to almost every shop in the Phoenix, Arizona valley that does automotive air conditioning. They said they haven't used it for years, can't get it, don't have the equipment, and said it would be nearly impossible to find. Even the ones that advertise that they use R-12 on their websites said they sold their equipment. Their advice was "just buy some adapter fittings and we can put in R-134a".

I did find a shop in Tucson that will charge with R-12, so I might be making a five hour round trip if I decided to stay with R-12. I'd rather NOT have my air conditioning blowing warm in stop and go traffic, which is what I'd expect out of R-134a, even though I replaced every component of the air conditioning system, including a 16" auxiliary fan, parallel-flow condenser, Sanden compressor, hoses, evaporator, expansion valve, etc. Keep in mind that we have 120F summers here. It was 112 just a few days ago.

Anyway, as nice as sticking with R-12 sounds, it seems very difficult to find a place that will charge with it--even if you brought them the bottles they still won't touch it.

I am fortunate to have a supply of R12 and a shop that has the equipment to charge these systems. Although R12 is preferred, the larger fan, P.F. condenser, new hoses and a clean evaporator will provide better cooling with 134a than the stock components would have. I think you might be surprised. Of course there is always R152a (computer duster). It is cheap and will give similar cooling to R12.

Either way, be sure to use Ester oil in the system (6 oz in the compressor, 2 oz in the rest). It works with either refrigerant.

Diseasel300 · #**438** 06-26-2018, 09:59 AM

Quote:

Originally Posted by Squiggle Dog

For those interested, at the advice of the "stay with R-12" crowd, I called around to almost every shop in the Phoenix, Arizona valley that does automotive air conditioning. They said they haven't used it for years, can't get it, don't have the equipment, and said it would be nearly impossible to find. Even the ones that advertise that they use R-12 on their websites said they sold their equipment. Their advice was "just buy some adapter fittings and we can put in R-134a".

I did find a shop in Tucson that will charge with R-12, so I might be making a five hour round trip if I decided to stay with R-12. I'd rather NOT have my air conditioning blowing warm in stop and go traffic, which is what I'd expect out of R-134a, even though I replaced every component of the air conditioning system, including a 16" auxiliary fan, parallel-flow condenser, Sanden compressor, hoses, evaporator, expansion valve, etc. Keep in mind that we have 120F summers here. It was 112 just a few days ago.

Anyway, as nice as sticking with R-12 sounds, it seems very difficult to find a place that will charge with it--even if you brought them the bottles they still won't touch it.

The difficulty and expense of staying with R12 is what made me decide to try R134a and the alternates (R152a and R290 [propane]). I have a half full can of R12 with about 10 lbs left in it, but the valve is bad, so as soon as it's opened gas comes spraying up all around the handle.

The Gen II W126 has a factory A/C setup very similar to what you've converted yours to. Denso compressor (very similar to the Sanden) and the small-tube dual-circuit condenser which not as good as a parallel-flow is still a significant improvement over the large tube small condenser of the earlier cars. I do have a replacement R134a expansion valve installed which is all that is available for my car nowadays. Not sure about the flare-fitting version in the older vehicles or if it even makes any difference.

I was very disappointed with the performance of R152a and R290. Both cooled excellently with some engine RPM and movement, but fell far short at idle. Any RPM above 1000 and they cooled great, but if you coasted for a while or stopped, you could expect 62˚ vent temps. That isn't acceptable in my book, sorry. I tried everything, I put gas in, pulled gas out, did the hokey-pokey......you get the picture.

I finally gave up and decided to try 134a. Initially I charged by weight at 80% and while an improvement over the 152 and 290, it was still lacking in performance, especially on a really hot day (>95˚). I decided to tweak the charge and added gas until the pressures and vent temps matched what I wanted and I ended up somewhere around 87% of the R12 charge by weight. With the charge tweaked, I have 0 complaints about the performance of the A/C. Even on a 104˚ day like it was this weekend, it was capable of blowing 44˚ at the center vent. Idle performance is significantly better, it will usually hold within 5-7˚ of the moving temperature. Once it pulls the cabin down I've never seen it above 51-52˚ at the center vent at idle.

My point isn't to brag about my car or give false expectations, it's just to give a datapoint on what can be done with a later stock system (or upgraded earlier system) when you take the time to dial in the refrigerant charge instead of wildly dumping in random amounts of gas and hoping for the best. I never see temps above 110 in this area, so I have no idea what it would do at 120˚, but even in the low triple-digits my converted A/C in the SDL blows colder, faster, and harder than any of the modern vehicles I have access to with factory R134a systems in the same conditions. At some point in the future I may convert the condenser to a PF style if it develops a leak, but for now I'm satisfied with how it is and can't really ask for it to do any more. I currently have no window tint and that's something that's rocketing to the top of the "to-do" list. I suspect that will help out even more.

Squiggle Dog · #**439** 07-22-2018, 04:54 PM

What do you think of using double end-capped PAG100 with R-12? I've heard it's compatible with both R-12 and R-134a, and that's the oil Klima recommends when converting to a Sanden compressor and using R-12 (Sanden also seems to list it as the only oil they endorse for their compressors). I'd like the flexibility of using an oil compatible with both refrigerants in case I'm forced to use R-134a in the future, and PAG100 is supposed to be superior to ester oil.

I definitely don't want to use mineral oil because it's not compatible with R-134a and I don't want to deal with flushing out all the old oil if I am forced to use R-134a in the future. My entire system is going to be brand new, so there will be no residual oils of any kind. I understand the reason people like to use ester oil so much is because it can mix with all oil types to some extent, but this will not be necessary in my case.

Junkman · #**440** 07-22-2018, 05:04 PM

For the record, I think there are several sets of unused R12 gauges that I bought years ago when selling at the flea market. $25+ shipping. PM and I'll make the trip out to my shop where they are stored. They should still be there unless the metal thieves stole them when they ransacked the place.

Squiggle Dog · #**441** 07-22-2018, 05:45 PM

Quote:

Originally Posted by Junkman

For the record, I think there are several sets of unused R12 gauges that I bought years ago when selling at the flea market. $25+ shipping. PM and I'll make the trip out to my shop where they are stored. They should still be there unless the metal thieves stole them when they ransacked the place.

Thanks! I'll probably have a professional shop do the charging, though, so they can pressure test the system and all that. I don't want to mess it up by doing it myself.

Also, I assume it's safe to drive with no oil in the compressor as long as the clutch isn't engaged? I want to deliver the car with the compressor emptied of the shipping oil and flushed out and drained with DEC PAG100 oil so the shop can add the proper amount after vacuuming.

I'm seeing bottles of DEC PAG100 saying they are compatible with both R-12 and R-134a, so I imagine it should be fine to use with R-12 in my case since there will be no residual oil for it to mix with. Also, it seems a big part of the reason people don't use DEC PAG100 much is because of the higher price. I don't care how much it costs. I'm going to be paying the big bucks for R-12, anyway. I don't want wimpy air conditioning in Arizona heat.

ROLLGUY · #**442** 07-22-2018, 06:35 PM

Quote:

Originally Posted by Squiggle Dog

Thanks! I'll probably have a professional shop do the charging, though, so they can pressure test the system and all that. I don't want to mess it up by doing it myself.

Also, I assume it's safe to drive with no oil in the compressor as long as the clutch isn't engaged? I want to deliver the car with the compressor emptied of the shipping oil and flushed out and drained with DEC PAG100 oil so the shop can add the proper amount after vacuuming.

I'm seeing bottles of DEC PAG100 saying they are compatible with both R-12 and R-134a, so I imagine it should be fine to use with R-12 in my case since there will be no residual oil for it to mix with. Also, it seems a big part of the reason people don't use DEC PAG100 much is because of the higher price. I don't care how much it costs. I'm going to be paying the big bucks for R-12, anyway. I don't want wimpy air conditioning in Arizona heat.

Regardless of what oil you use, you should fill the compressor with the proper amount before mounting it on the bracket in the car. If you are using a fairly new compressor, it will already come with the proper amount of R134a compatible oil (either PAG100 or 46). If you drain the compressor well (fill and rear ports), there should be no need to "flush" it in any way. I believe the proper amount is 200cc of oil (or something close to that). Normally the complete system will require about 8oz total of oil. I usually put about 6oz in the compressor, and the remaining 2oz gets mixed with dye and added during the charge process (after vacuum).

Squiggle Dog · #**443** 07-22-2018, 11:08 PM

Quote:

Originally Posted by ROLLGUY

Regardless of what oil you use, you should fill the compressor with the proper amount before mounting it on the bracket in the car. If you are using a fairly new compressor, it will already come with the proper amount of R134a compatible oil (either PAG100 or 46). If you drain the compressor well (fill and rear ports), there should be no need to "flush" it in any way. I believe the proper amount is 200cc of oil (or something close to that). Normally the complete system will require about 8oz total of oil. I usually put about 6oz in the compressor, and the remaining 2oz gets mixed with dye and added during the charge process (after vacuum).

I was hesitant on adding oil to the compressor for two reasons: 1. I wasn't sure what type of oil to use or how to measure how much I'd need and 2. I wasn't sure if vacuuming the system would suck out the oil.

The Sanden probably has PAG100 in it, but I don't know for sure, and don't know if it's single or double end-capped. So, I figured draining the original oil, adding some new DEC PAG100, and then draining should clear out whatever's in there.

I guess I can add the proper amount of oil if I can measure it in some way.

ROLLGUY · #**444** 07-23-2018, 12:15 AM

Quote:

Originally Posted by Squiggle Dog

I was hesitant on adding oil to the compressor for two reasons: 1. I wasn't sure what type of oil to use or how to measure how much I'd need and 2. I wasn't sure if vacuuming the system would suck out the oil.

The Sanden probably has PAG100 in it, but I don't know for sure, and don't know if it's single or double end-capped. So, I figured draining the original oil, adding some new DEC PAG100, and then draining should clear out whatever's in there.

I guess I can add the proper amount of oil if I can measure it in some way.

Vacuuming does not get the oil out of the compressor. Again, 8oz is about what the system takes total. As far as the difference between DEC and SEC, I have no idea. I would think that whatever PAG100 that is commonly available would be the oil to use. I have seen two different labels on these compressors. One says SP 15, and the other SP10. One may be PAG46, and the other PAG100. I believe the number relates to viscosity. I am not the oil expert, I leave that up to Chris- my A/C tech.

Capn Jonas · #**445** 07-23-2018, 09:13 AM

My W124 2.5diesel's A/C leaks, Replaced compressor, condenser, dryer 2 years ago and it held for a year. Now it leaks down in a matter of a couple of days. Any likely sources for me to look? Thoughts about tools to pressure test the system?

Squiggle Dog · #**446** 07-23-2018, 10:15 AM

Quote:

Originally Posted by ROLLGUY

Vacuuming does not get the oil out of the compressor. Again, 8oz is about what the system takes total. As far as the difference between DEC and SEC, I have no idea. I would think that whatever PAG100 that is commonly available would be the oil to use. I have seen two different labels on these compressors. One says SP 15, and the other SP10. One may be PAG46, and the other PAG100. I believe the number relates to viscosity. I am not the oil expert, I leave that up to Chris- my A/C tech.

Good to know. Single end-capped PAG100 isn't R-12 compatible because the refrigerant turns the oil to acid, or something.

ROLLGUY · #**447** 07-23-2018, 11:27 AM

Quote:

Originally Posted by Capn Jonas

My W124 2.5diesel's A/C leaks, Replaced compressor, condenser, dryer 2 years ago and it held for a year. Now it leaks down in a matter of a couple of days. Any likely sources for me to look? Thoughts about tools to pressure test the system?

Pressurize the system with a dry gas, and spray all connections with soapy water. A leak that size should be very easy to find.

vstech · #**448** 07-24-2018, 10:09 AM

Quote:

Originally Posted by Squiggle Dog

Good to know. Single end-capped PAG100 isn't R-12 compatible because the refrigerant turns the oil to acid, or something.

Nope...

Acid is formed in the presence of oxygen and water.

R12 has no issues with any oil.

134MUST use an oil compatible with it.

Squiggle Dog · #**449** 07-24-2018, 02:22 PM

Quote:

Originally Posted by vstech

Nope...

Acid is formed in the presence of oxygen and water.

R12 has no issues with any oil.

134MUST use an oil compatible with it.

For whatever reason, whenever I see a bottle of single end-capped PAG oil, it states on it "not for use with R-12" and I've read countless times on various forums that it can't be used with it. But, when I see bottles of double end-capped PAG, it always seems to state "compatible with R-12 and R-134a". Maybe it has more to do with how well the PAG oil mixes with mineral oil, which is not a concern in my case because there is no mineral oil left in my system.

But, it looks like the oil I am going to be using (double end-capped PAG100) should be a decent oil that will work with whatever refrigerant I put in there. I got a good deal on 12 oz of it on eBay. I can't believe the local AutoZone wanted $55.99 for just 8 oz of it.

ROLLGUY · #**450** 07-24-2018, 02:39 PM

Quote:

Originally Posted by Squiggle Dog

For whatever reason, whenever I see a bottle of single end-capped PAG oil, it states on it "not for use with R-12" and I've read countless times on various forums that it can't be used with it. But, when I see bottles of double end-capped PAG, it always seems to state "compatible with R-12 and R-134a". Maybe it has more to do with how well the PAG oil mixes with mineral oil, which is not a concern in my case because there is no mineral oil left in my system.

But, it looks like the oil I am going to be using (double end-capped PAG100) should be a decent oil that will work with whatever refrigerant I put in there. I got a good deal on 12 oz of it on eBay. I can't believe the local AutoZone wanted $55.99 for just 8 oz of it.

Something is wrong with that. I see 8oz bottles at all the stores for around $12.