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Discussion Starter #1 (Edited)
Hi,

Having got the heater box out and refurbished all the flaps (as well as removing a collection of old pens, combs and 1/2 a coat hanger), it struck me that I'd be stupid not to replace the evaporator, expansion valve and A/C hoses while I had everything in pieces. The car had stood for 16 years, and the AC Belt had been removed even before then, so I have no idea what the state of the system is.

I have a few questions:

1) Does anyone know a vendor who sells complete (i.e with connectors) new A/C lines for the earlier 450SL? (it looks like the lines changed in 76, and there seems to be plenty for sale for later cars). I'd prefer to get 'new' lines, as (I hope) they would be constructed of barrier hose, as I'd plan to use R134a.

2) Looking at the attached EPC diagram, # 92 (A1078300096) looks to be the complete hose from the Evaporator to the compressor manifold (not shown); but when I check online pricing seems to be surprisingly reasonable (around $25 at most online MB places). Is this part number actually the complete hose, or just the hose (to which connectors have to be added)

3) It looks like 4 Seasons ( 54131 ) is pretty much the only option for the evaporator (other than a few MB OEM's at silly money). I've noticed that Four Seasons seem to not get the highest ratings, but that seems to be mainly on compressors (and I can leave that for a while - just want to get the heater box back in and the dash fitted). Does anyone have any experience (good or bad) with the Four Seasons expansion valves or evaporators.

Thanks in advance!!

(and a callout to AussieMerc, and all his postings on the heater box - couldn't have done that without that help!!)
 

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1. I looked for, but could not find, a vendor offering 450SL hoses (mine is a 78) utilizing barrier hose. I bought a hose from MB, it used non-barrier. So I had them made by Charlie Griffiths, a friend of mine from the Porsche community. https://griffiths.com. He doesn't regularly do this but I asked him nicely and he delivered. I sent him my old hoses and he rebuilt them with Parker Futura.
No leaks, no issues.

2. #92 in diagram is in fact the complete hose assembly with crimped connectors, that goes between the outlet from the evaporator under the dash forward to the compressor manifold (as you correctly call it). This is the hose that I was able to source, has the right crimps, but not a barrier hose. Also, the original hose has a metal section on the evaporator end that is probably eight inches long-- the factory hose just has a conventional crimp connector on that end.

3. I used a four seasons TXV and compressor (a rebadged aluminum Delco) and these were both fine. I wouldn't have a problem putting their evaporator back in my dash.

Are you converting to R134a? The TXV is specific to that refrigerant and of course you need the correct oil.

Hope this helps

Good luck!
 

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Discussion Starter #3 (Edited)
1. I looked for, but could not find, a vendor offering 450SL hoses (mine is a 78) utilizing barrier hose. I bought a hose from MB, it used non-barrier. So I had them made by Charlie Griffiths, a friend of mine from the Porsche community. https://griffiths.com. He doesn't regularly do this but I asked him nicely and he delivered. I sent him my old hoses and he rebuilt them with Parker Futura.
No leaks, no issues.

2. #92 in diagram is in fact the complete hose assembly with crimped connectors, that goes between the outlet from the evaporator under the dash forward to the compressor manifold (as you correctly call it). This is the hose that I was able to source, has the right crimps, but not a barrier hose. Also, the original hose has a metal section on the evaporator end that is probably eight inches long-- the factory hose just has a conventional crimp connector on that end.

3. I used a four seasons TXV and compressor (a rebadged aluminum Delco) and these were both fine. I wouldn't have a problem putting their evaporator back in my dash.

Are you converting to R134a? The TXV is specific to that refrigerant and of course you need the correct oil.

Hope this helps

Good luck!
Thanks!

Yes - I am planning to use R134a (or maybe EnviroSafe - still investigating that). I didn't realize the TXV needed to be different, based on the refrigerant. As it sounds like you also went the R134a route, which Four Seasons valve model did you use? (I see 38604 listed at most sites for the R107, but I assume that's intended for the original R12). Also - did you use the 4S Model 58098 compressor? (it's good to hear some feedback on that, as I had been considering that..)

-Steve

Edit: Just found your thread covering your A/C rebuild - answers a bunch of other questions I had - definitely bookmarking that!!
 

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Do not use R134a. It works ok up to apprx 95 to 98 degrees outside temperature, and then it gives up. You will find that opening the windows with outside temps over 100 degrees is cooler than running your AC. Your cores are just not big enough to make up for its lower effectivness.
 

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Thanks!

Yes - I am planning to use R134a (or maybe EnviroSafe - still investigating that). I didn't realize the TXV needed to be different, based on the refrigerant. As it sounds like you also went the R134a route, which Four Seasons valve model did you use? (I see 38604 listed at most sites for the R107, but I assume that's intended for the original R12). Also - did you use the 4S Model 58098 compressor? (it's good to hear some feedback on that, as I had been considering that..)

-Steve

Edit: Just found your thread covering your A/C rebuild - answers a bunch of other questions I had - definitely bookmarking that!!
Fixer,
I just ordered the enviro-safe Kit today $34.95 and many others here have used enviro-safe and are real happy with the outcome. As I even spoke to one of the person in sales and he indicated the alternate kit is the way to go but make sure that you do not exceed 35lbs psi. And the adaptors fittings you will need #3005 low and #3020 high side. I have some R12 in my system and I'm adding enviro-safe to it. Also if for some reason later the system leaks, he mention to add then the "stop leak" provided in the kit and then add more enviro-safe.
 

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Discussion Starter #8
I used the 4 seasons TXV. No issues in two years. No experience with the evaporator.
Thanks! I've already bought the evaporator and TXV (both Four Seasons).

It looks like everyone is recommending EnviroSafe (thanks for all the recommendations), so I have some questions:

a) I'm assuming that the TXV I've bought ( 38604 ) will be ok for the EnviroSafe ( 304065 mentioned earlier in the thread that the TXV was refrigerant dependent). I'm wondering if there's a better option here - even though I've got the TXV ordered, I'm prepared to change if there's something definitely better.

b) Those of you using EnviroSafe, did you bother with getting modern barrier hose, or did you use OEM (My hoses are so old, I'm going to replace anyway, but trying to decide the route to go - finding OEM, or getting a set made up (304065 recommended a shop, but not called them yet). I'm kind of amazed that there doesn't seem to be a specialist I can order a set of hoses from 'off the shelf'

c) Any thoughts on the condenser? I see RockAuto lists the APDI/PRO 7014075 at a very reasonable price. Knowing that the R107 system is pretty weak to start with, if a modern condenser can give me a few more degrees cooling I'm happy to replace that (and I'm also worried about any debris/oil oils that might be lurking in the original after so long wrecking a new compressor. Currently considering the 'small' 4 seasons aluminum compressor (58098)

Thanks!
 

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Why not pay a shop to do a full flush of the system. They do not need to do more than slap in some of the oil appropriate to your choice of cooling medium. The system was designed to run R12, which puts the R134 junk to shame. Find a replacement compressor that will function with R12, and you could use some of the canned air stuff (same cooling coefficient as R12) to recharge the system.
 

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Discussion Starter #11
Why not pay a shop to do a full flush of the system. They do not need to do more than slap in some of the oil appropriate to your choice of cooling medium. The system was designed to run R12, which puts the R134 junk to shame. Find a replacement compressor that will function with R12, and you could use some of the canned air stuff (same cooling coefficient as R12) to recharge the system.
Unfortunately, not really practical at the moment - the car is in pieces, in the middle of a restoration. As the heater box is out, and the hoses looked pretty crappy I decided to replace them (and the evaporator) while I'm in there. Based on the recommendations here I do plan to refill with Envirosafe, though that's several months away - just want to get the hoses in place while it is easy.

Also: I've found a place in Florida (coldhose.com) who will be making up the hoses for me; I'll post here once I get them back. Their web site allows you to specify exactly what you need, or you can ship the hoses to them and they will copy them. I'm probably going to send them, just to avoid any mistakes (also, it appears that the firewall gasket for the hose to the condensor is probably easier to put on the hose while it is being manufactured)

-Steve
 

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I miss the "old days" when AC work was straight forward. Use R12, add mineral oil, and install a new A6 compressor-- everything worked great, cooled nicely and it all lasted a long time. It’s complicated now-

1)R12 is a problem to get-- some of the aftermarket "propane" refrigerants seem to work. Don't use 134a unless your AC is specifically designed for it (not modified to use it).

2)Oils-- Pag is the better current oil now but it is not compatible with R12 or mineral oil, which might be still be in the system. Ester oil is cross compatible- but it is not as good of a lubricant. The compressor really must be one that is ok with Ester. --

The Delco A6 will work with ester oil, but it really doesn’t like it.
The Four Seasons compressor doesn't really like ester oil either.
The Pro6ten compressor is ok with Ester oil.

You can’t get a good new GM Delco A6 anymore- - The rebuilds are sometimes good, or very often, they are not.-- They run ok for a while and then many quit.

The new Four Seasons compressor is available and was also sold by GM/Delco "somewhat", but Delco seems to be avoiding it now - The Four Seasons compressors are really are not all that great- Some who use them have good luck and some don’t.

The Pro6Ten compressor is sold by Classic Air- -It is a modified Aluminum rotary compressor to match the dimensions of the original A6- - The early ones had some issues sometimes. They ones sold now seem pretty good. This might be the better current choice. And it will work with PAG, Mineral oil, or ester.
 

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Discussion Starter #13
I miss the "old days" when AC work was straight forward. Use R12, add mineral oil, and install a new A6 compressor-- everything worked great, cooled nicely and it all lasted a long time. It’s complicated now-

1)R12 is a problem to get-- some of the aftermarket "propane" refrigerants seem to work. Don't use 134a unless your AC is specifically designed for it (not modified to use it).

2)Oils-- Pag is the better current oil now but it is not compatible with R12 or mineral oil, which might be still be in the system. Ester oil is cross compatible- but it is not as good of a lubricant. The compressor really must be one that is ok with Ester. --

The Delco A6 will work with ester oil, but it really doesn’t like it.
The Four Seasons compressor doesn't really like ester oil either.
The Pro6ten compressor is ok with Ester oil.

You can’t get a good new GM Delco A6 anymore- - The rebuilds are sometimes good, or very often, they are not.-- They run ok for a while and then many quit.

The new Four Seasons compressor is available and was also sold by GM/Delco "somewhat", but Delco seems to be avoiding it now - The Four Seasons compressors are really are not all that great- Some who use them have good luck and some don’t.

The Pro6Ten compressor is sold by Classic Air- -It is a modified Aluminum rotary compressor to match the dimensions of the original A6- - The early ones had some issues sometimes. They ones sold now seem pretty good. This might be the better current choice. And it will work with PAG, Mineral oil, or ester.
Thanks - that's a very useful summary!

Currently, it looks like the only two original parts left in my system once it's done will be the suction pipes (all steel on a '76 SL), and the condensor.

The suction pipes will be easy to clean out once they are out of the car. Would you recommend replacing the condensor as well? (given it probably contains old oil, and has been sat in the car unused for at least 20 years.?)

I'd seen lots of 'universal' condensors for sale at a surprisinly reasonble price (<$100 US), but was concerned about their fit, especially to the dryer and hoses (everything is pretty tight in that corner)

-Steve
 

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MB AC hoses

Thanks - that's a very useful summary!

Currently, it looks like the only two original parts left in my system once it's done will be the suction pipes (all steel on a '76 SL), and the condensor.

The suction pipes will be easy to clean out once they are out of the car. Would you recommend replacing the condensor as well? (given it probably contains old oil, and has been sat in the car unused for at least 20 years.?)

I'd seen lots of 'universal' condensors for sale at a surprisinly reasonble price (<$100 US), but was concerned about their fit, especially to the dryer and hoses (everything is pretty tight in that corner)

-Steve
For what it's worth, I just purchases low and high side AC hoses from the dealership for my 1977 450SL. $29.00 for the low side and $32.00 for the high side. I installed the low side by just removing the bottom panel under steering wheel and the steering wheel. Difficult, but I was able place a open end wrench on the expansion valve and another wrench on the low side hose to re-assemble and to assemble.
 

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The stock MBZ condenser coil was a good quality build, but- its current condition is important. If it is still solid- no bangs, crimps, corrosion, and such--- That is good. You say it was sitting. That is not a big problem as long as it appears basically clean and is not jammed with dirt. Absolutely use a specific AC flush solution and pressure force it through the coil. You can get pressure bottles for this purpose at a low cost, eBay or other sources. Fill the bottle with solution and pressure charge with an air compressor hose, then flush through the coil. Always flush one component at a time, do no flush multiple components. The coil must be dried out after the flush. Nitrogen is best but you may not have it available. You can use compressor air but be sure that it is not coming from a compressor line which sends out globs of water or dirt, you might need a filter, don’t run the pressure too fast as that tends to send out stuff. After a higher pressure blow out of the solution, a low-volume flow of air through the core for a while can assure it is a dry as possible.
 

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Discussion Starter #16
For what it's worth, I just purchases low and high side AC hoses from the dealership for my 1977 450SL. $29.00 for the low side and $32.00 for the high side. I installed the low side by just removing the bottom panel under steering wheel and the steering wheel. Difficult, but I was able place a open end wrench on the expansion valve and another wrench on the low side hose to re-assemble and to assemble.
I think the 77 is the same as the '76 (you still have the manual/cable slider controls on the dash correct?)

Do you know what the part numbers were? I couldn't see a part number for the evaporator-drier - that seemed to come as hose and two connectors from MB according to the EPC.

My current assumption was the the OEM hoses wouldn't be barrier hoses, so would leak R134a. I'm probably now going with Envirosafe, so I don't know if that's still an issue - but it would be nice to know I could switch to R134a if I had to in the future. That said, odering 'off the shelf' would be a lot easier...

-Steve
 

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Discussion Starter #17
The stock MBZ condenser coil was a good quality build, but- its current condition is important. If it is still solid- no bangs, crimps, corrosion, and such--- That is good. You say it was sitting. That is not a big problem as long as it appears basically clean and is not jammed with dirt. Absolutely use a specific AC flush solution and pressure force it through the coil. You can get pressure bottles for this purpose at a low cost, eBay or other sources. Fill the bottle with solution and pressure charge with an air compressor hose, then flush through the coil. Always flush one component at a time, do no flush multiple components. The coil must be dried out after the flush. Nitrogen is best but you may not have it available. You can use compressor air but be sure that it is not coming from a compressor line which sends out globs of water or dirt, you might need a filter, don’t run the pressure too fast as that tends to send out stuff. After a higher pressure blow out of the solution, a low-volume flow of air through the core for a while can assure it is a dry as possible.
Thanks - that's very useful to know; didn't realize you could get flush solution etc. I'll pull the condenser and take a careful look at it. The fins look a little bent, but can't see any serious damage to it.

-Steve
 

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Okay, I ran into a problem with the high pressure hose on my 1977 450SL. MB new High Pressure hose connection to the compressor is fine but to the condenser its an incorrect fitting, as it has the same fittings as to the AC Compressor. My high pressure hose was previous replaced and as to when I was taking out the old receiver/dryer I had notice that the high pressure hose was clamp on the condenser by ordinary hose clamps (2). Today I removed the high pressure hose at both ends and you can see in photo what the my condenser connection looks like after I removed the hose clamps. So I now believe that I'm going to have to remove the condenser completely from the car and have the new high pressure hose cut and professionally attached. I'm assuming the factory condenser comes with the high pressure hose, a non removable permanently attached to the condenser. Can someone verify my conclusion.... or come up with a better alternative. I also attached a photo (marked 2) of my friend's 79 SL and you can clearly see how the compressed connection to the condenser came from the factory.
Thanks,
carltwo
 

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Yes-- The early ones did have a crimped hose on the top condensor connector. Remove the core and take it to an ac shop. They can use a crimper to put a new hose on it. The hole on the core side of the crimp ferrel most generally must be ground somewhat to fit over the connector on the core.
 

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Yes-- The early ones did have a crimped hose on the top condensor connector. Remove the core and take it to an ac shop. They can use a crimper to put a new hose on it. The hole on the core side of the crimp ferrel most generally must be ground somewhat to fit over the connector on the core.
rick,
Appreciate the confirmation...
carltwo
 
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