1996 (7?) S320 Limo air-con problem

I have just bought a S320 Limo, first registered Jan 1997 - so probably a 1996 build.

Everything is fine except the air-con.

I am trying to avoid using a dealer - they charge a fortune in the UK.

My friendly air-con man has checked the system and re-gassed as far as he is able. A certain quantity of gas has been pulled in by vacuum. Now he needs the compressor to run to pull in the rest.

Unfortunately, the compressor has been disabled by the safety device triggered by lack of gas. The EC (economy) button is permanently lit.

I understand that a Mercedes dealer can disable this device so that the compressor can be run to finish the gassing process, but they will insist on doing the entire re-gas for a bucket-load of money.

On my previous car - a Jaguar - it was possible to over-ride the equivalent safety feature by pressing two buttons on the air-con control panel simultaneously (a well known but undocumented "feature").

Is there any way round this so that my friend can complete the process, or do I have to go to an MB dealer (and arrange a new mortgage)?

TIA

Geoff

[jbaj007]

Have you tried jumper on the low pressure cut-off switch?

Originally posted by jbaj007
Have you tried jumper on the low pressure cut-off switch?

No we haven't. Do you mean a jumper present on the switch as in a jumper on a mother board? Sounds as though that could be what we want. Exactly where is it?

TIA

Geoff

[car54]

you need to remove the wire plug from the low pressure switch on the AC system. you then jump it with a piece of wire with the car running and the climate control in the on position. watch and listen for the compressor to come on when you just the wires. dont let it run long, this will tell you that there is either low freon OR a bad pressure switch, both easy fixes. for the location of the switch, I cannot help you.

Many thanks.

Geoff

[A. Rosich]

I just hope you may be able to correct your problem with a simple freon charge. If you fall into evaporator problems (the most popular reason why freon is lost in W140s cars), be ready to mortage your house, your family, and your dog for about 40 years worth.

A. Rosich
S320, 1998
E320T, 1995

Eek!

So far the system has survived a 160psi pressure test with nitrogen, so I hope all will be well.

Fortuantely, it is the dealer's problem - it emerged the day I picked the car up. He seem sto be accepting responsibility (so far).

I'll let you all know the outcome.

I did go down the "new compressor" route with an old Jaguar years ago. Never again :-)

Geoff

[A. Rosich]

Geoff, be sure that the dealer takes FULL responsability for the repair. Keep a constant eye on how the system performs.

I have to see up to date a W140 that has NOT yet need MAJOR A/C work. It is really a shame. Such a great car with such an unreliable A/C system.

Although, the E class is not excluded. My E320T needed a new evaporator at 22,000 Kms. (Three years old). It seems that the alluminum core installed at the factory rusts very easily. I installed a copper core unit which is guaranteed for life.

A. Rosich
S320, 1998
E320T, 1995

Many thanks.

I'll bear that in mind.