Hi,

First time posting - please be kind ;-)

Am having a strange experience with my ML320 CDI 2007: ~197,000 kms down here in Melbourne, Australia.
Brought he car very cheap about 8 years ago as it still needed the o-rings done on the heads - oil coming out of the heads - had that done and one other incident where the front belt jumped of twice - bad harmonic balancer. Since then just regular services, tyres, brakes, service etc.

The air conditioning stopped working about 3 weeks ago (middle of summer here - everyone on holiday - no techs available - very hot - great timing!) and about 2 weeks ago light stated comin back on after starting indicating glow plug fault.
Take the car down to my diagnostic guru (when he comes back from holidays) - had to drive the car for 3 weeks without air conditioning, fan running flat out, windows down, sun roof open - old style air-conditioning ;-)

My tech guy gives me the bad news: 88(!) faults listed in HVAC - with faults against
- ME/CDI/CGH,
- ABS/ESP, AB - Aribag,
- EZS/EIS - Electronic ignition lock,
- LCP/HBF - Lower Real control panel,
- OCP - Overhead control panel,
- RevETR-LF - Left front reversible emergency tensioner retractor,
- RevETR-RF - Right front reversible emergency tensioner retractor,
- SAM-F/SAM-D - Signal acquisition and actuation module front/driver side,
- SAM-R/BSN - Rear signal acquisition and actuation module/Batter sensor
- SCM [MRM] - Steering column module
- System diagnosis
- UCP - Upper Control panel
- AWG - Audio Gateway
- AVE-H - Rear audio video unit
- IC - Instrument cluster
- PTS - Parktronic system
- DCM -FL - Door control module front left
- DCM - FR - Door control module front right
- ESA Driver - Electric seat adjustment Driver
- AAC - Automatic air conditioning
Note: A number of the faults are "The supply voltage of the control unit.... is too low (undervoltage)"

I can post images of all the codes if that helps.

And the rest of the systems had no reported faults

And the 3 glow plugs (cylinders 1, 2 & 4) are showing faulty.

Detailed analysis of the air conditioning showed that the compressor was being commanded correctly (i.e. electrics seem ok) & would begin "pull down" but unable to fully comply - conclusion air conditioning compressor stuffed & needs replacing - seems to be correct.

My tech guy is able to clear all except 2 faults which are long standing issues to do with the towing wiring setup and predate this current set of issues.
His advice is "get rid of the car - glow plug issues can be a pre-cursor to major issues with the engine". I'm not so sure - thus this posting.

The mystery is why the glow plugs have gone as well as the air-conditioner - I'm thinking this is not a co-incidence.
Theory is that one of one the faults (low voltage??) caused the glow plugs to stay on too long (sticky / low voltage relay) or too much voltage and effectively burn out - has anyone else had anything like that happen?
Perhaps running the fan flat out & the hot weather created low voltage situation. Or perhaps the glow plugs short or placed extra load and cause a low voltage situation.

The car has a bit of a history of "glitchy" electronics - never thus bad before.
e.g. put the key into the ignition, turn it - nothing - take the key out, put it back in and it starts find.
And service techs regularly report a few codes that need clearing - but everything seems to work fine.

Thoughts? Opinions?

Regards,

Neeto