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450SE Air Conditioning

Started by simon132, 17 December 2005, 05:40 AM

simon132

I have a Australian delivered 1976 450SE with the original Type 1 R11 air conditioning.  Naturally it doesn't work and I would like to get it back going.  I had a a/c guy have a look at it and said it had a couple of leaks.  What should I do? Can I upgrade to Aus spec RXX and if so how?  Any other advice would be appreciated as I don't want to waste time or money.

BTW, the heater works great.  You could cook with it!

OzBenzHead

Quote from: simon132 on 17 December 2005, 05:40 AM... Can I upgrade to Aus spec RXX and if so how?  Any other advice would be appreciated as I don't want to waste time or money.

Simon:  Unless you'll be content with aircon that is ineffective under 40 km/h, try not to waste the money.

Putting R134a in an R11 or R12 system gives, generally, unsatisfactory results at city speeds. It certainly won't keep you cool in peak hour gridlock.

There is, however, an "interim" gas (don't have a number for it) that nobody advertises cos there's not as big a profit in it as there is in upgrading old systems, (which is necessary to get adequate cooling with R134a). A local(ish) Holden dealer dispenses it in these parts of the world, and I'm off to visit him soon.

I've seen it written / heard it said (perhaps somewhere on this forum?) that the rotary style compressor copes better with the crappier gas; if yours is rotary - as is mine on the 1979 116 - you might get away with it.

Those "couple of leaks" just might prove expensive; suggest you get a firm quote before embarking on that journey.

Good luck.   :)
[img width=340 height=138][url="http://i12.photobucket.com/albums/a215/OzBenzHead/10%20M-B%20Miscellany/OBH_LOGO-2a-1.png"]http://i12.photobucket.com/albums/a215/OzBenzHead/10%20M-B%20Miscellany/OBH_LOGO-2a-1.png[/url][/img]

john skene

Simon132. To make you feel a little more comfortable I had my airconditioner refurbished with a rebuilt compressor, new drier plus the new gas, and it works great. But leaks in the system can be a problem. If the leaks are in the joints, hoses or condensor they can be fixed without too much problem, but if it is in the heater assembly you are looking at 5 hours work to take it out, 5 hours to install, plus the time to find the leak and fix it. Even at a low hourly rate this can be expensive.
If you have to take the heater assembly out thats the time to fix any dash cracks (dash comes out) and check the heater flaps, levers etc to get it working 100%.

john skene

Your right Styria, I'm obviously not adding up the hours correctly. It took me 5 hours to take the dash out of a dismantler, when the centre console was already out, and I did not take out the heater assembly. It would have taken me longer than 5 hours to put the dash back properly, and then there is all the interior to refit.  I am informed the heater assembly is rather difficult to work with so I am putting off work on mine until the weather cools down a bit.

WGB

For my two Bob's worth.

I refurbished my 450SEL A/C with New Compressor, mainly new pipework, new electric Fan, new receiver/dryer and conversion to 134A gas. The cost was AUD$1600 about 18 months ago.
I was advised to change to a larger condenser, and replace the expansion valve.
I decided the budget didn't warrant a new condenser and the installer couldn't find the expansion valve (subsequently easily located when the instruments are removed).
It works well enough although I am never in stop start traffic. Initially the car seemed to run hot even after the radiator was cleaned by removal and rodding but after checking on various forums found that the 450 will heat up if the ignition is too far advanced. As I couldn't find the correct timing for my British Spec 450 I retarded it a little at a time and now it runs ver well and very happily at 175 fahrenheit on the (British Spec)gauge even with our 40 degree Celcius days in Summer.

Bill Babe
Western Australia
1979 450SEL

simon132

Bill, thank you for your two bob's worth.  I am still deciding whether to press ahead with the upgrade.  I have been able to source most of the components out of the US at a fraction of the local aussie cost, but I am just worried that once it is all pulled apart there will be more to it than meets the eye.

You mentioned the valve being hidden by instruments, which are they?

I use the car as a daily driver in urban Sydney so I am also conscious of the advice re the A/C being of little value at low speeds (that's all we have).

I used to be indecisive, now I can't make up my mind!

Cheers,

Simon

WGB

Hi Simon,

I asked all the local mechanics who they used when they had problems and found a local firm specialising in Auto A/C - Lyon's Airconditioning in WA. They knew what to do except they had some trouble with the electrics controlling the Electric fan - later I found a relay in the right kick panel of the driver's footwell that had long ago had a little drink of water and rusted out. They rewired the new fan and new pressure switch and did a good job.Although the fan is no longer connected to this relay - replacing it improved the whole A/C system as the relay also feeds the heater and A/C system.

The Expansion valve is easy to see after removing the instruments - speedo etc- sitting on the left hand side as you look into the opening (on the side of the heater box) after removing  the instruments in a RHD car.

As I said the expansion valve was not replaced as they did not know where to find it and as I did not want to pay for a new condenser I did not receive one.

The biggest improvement to make is to make sure the electric fan is functional and stays on for the whole time the compressor is active. I think the standard setting on all other earlier Benzes I have owned only pulled the electric fan in when it was needed to control the temperature and apparently 134A doesn't like this.
The system itself is made up of very standard ?GM parts and all are available in Oz. A Brand new compressor cost about $800 and a new electric fan about$160. The other costs were made up with some new hoses being manufactured (By Lyon's themselves) to fix leaks, new connectors (H134A Specific) and labour.
They also offered me a 12 month warranty but it has worked for 18 months with no problems.
The system is certainly quite adequate without being gobsmacking - it makes the car a useful daily car with our weather in WA.

Best of luck but suggest you spend some time finding someone in Sydney who is both honest and knows what they are doing.
At the end of it the A/C system is really only the same as you'd find in a Commodore - just hope you don't need to get into the heater box.

Bill

oscar

Hi all,

re: conversion

I'm a bit confused as to what I need to do to get my a/c going again.  I've read all the above and I'm on old gas that's been topped up by gas taken from wrecks.  Problem is there's too many leaks.  A regas will last maybe 6 months.  I saw a while back from the US a gasket and ring set that supposedly converted the system to r134a. 

I'm sure there's more to it.  But if I were to convert to r134a what do I need?  Who do I see?  What sort of cost? BTW my system has no fan up front either.  I see "WGB" spent $1600.

If my compressor's fine and the leaks fixed, can I just put r134a into the old system????  Can you buy gas and top it up yourself?  I know in the US you can buy aerosols cans to regas your a/c.
1973 350SE, my first & fave