When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hi
continuing the AC drama - 1998 ml 320
Went to the local MB dealer for o rings etc and was found out that 4oz of their PAG 45 - $275.00!!!
So work done so far - replaced
1. Expansion valve
2. AC compressor
3. AC line condenser to compressor
4. AC dryer
5. 3.5oz of PAG 45 to compressor (shipped dry)
6. Blend motor/ actuator
Added 12oz of RA135 - the system calls for 26oz
AC on - compressor running - face vents - blower motor at 3 - Cold air!!!!
Reading 6.5 bar - scanner
However the AC manifold gauges are wacky - outside ambient temp is 60 degrees (humid) High lowside pressure and low high side pressure
Does anybody know what is going on here?
Thanks Hi low side pressure - low high side pressure, compressor engaged, ambient temp 60degrees Cool air at in car air vents iCarsoft scanner live data ac system pressure Only added 12oz 134A system fully evacuated and on vacuum pump for 1 hr.
AC readings ok
Fitted an aftermarket AC compressor and battled some leaks - mainly at compressor suction fitting, hopefully new o ring has fixed this
The guages are now reading ok, and refrigerant pressure 14.5bar, there is cold air in the cabin.
Now the last issue - check engine light - P1453 stored
1. Air pump relay (K17)
2. Air pump relay (K17) relay module K76, fuse and relay module K40/4
cannot get rid of this annoying issue
Any advice welcome on this one
thanks
PDG
Thank you for your reply.
- Removed cover from relay K28, if I close contacts - no ignition on - air pump will run
- Start car relay does not close - if I close contacts Raif pump will run.
There must be no signal to that relay - what’s next?
Check engine returns after ‘clearing’
Hi
Thank you for your reply
I have in fact swapped out the relay, and this is the relay shown in the test - the thread on this issue will show that swapping this relay was one of the things done in an effort to solve this issue.
The fact that the relay works - ie sends power to the air pump, suggests that the problem is else where.
It must be that the NE/10 ME control unit is not sending a signal that K28 relay.
Surely this is not the only ML that has had this issue!
Thank you for your observation.
Not sure if this is the direction I want to take.
Difficult to move on if it is not possible to get a ‘state inspection’
There must be a logical explanation and equally logical fix for this.
As for a 22 year old Ml every thing else is functional and and in good shape
Thanks
If you have state inspection then it's a different story. Typically the electric air pump goes bad (either seizes or draws too many amps) and burns out the relay, which can in turn burn out the fuse box internally. The fuse box inside is layers of circuit boards.
Dear E55
Thank you for your reply
The relay and all things down stream - on this circuit are functioning ok.
It must be the signal to the BCM - (or the BMC itself) that is causing the issue
Questions -
1. where is the BCM located?
2. Does any one have a ‘pin out’ of the BMC showing what controls the K28 relay / 40 Amp fuse and air pump.
This is the last obstacle to overcome before handing this Benz over to my son. (He is currently driving a 2002 ML) which I will then give to my brother-in-law., my wife and I also drive 2002 / 03 ML’s each also have the high milage award from Benz
There are 2 additional small issues to overcome
1. The rear washer does not spray - the pump works.
2. Replacing the small bulb / illumination for the HVAC control.
I have the high milage award from Benz as this ML has over 250,000 miles and is running strong.
Keep calm and carry on Benzing.
Hi, Did you get your AC working properly in the end? My AC in my 2000 ML320 doesn't work, but I'm leaving it alone as it can get expensive to fix. Where I live there are only about three days a year when it would be useful... Well done on the high mileage awards! Mine has only done 126700 miles and only 16000 of those are mine, in the last nearly seven years, so I should get a low mileage award...
Hi, Did you get your AC working properly in the end? My AC in my 2000 ML320 doesn't work, but I'm leaving it alone as it can get expensive to fix. Where I live there are only about three days a year when it would be useful... Well done on the high mileage awards! Mine has only done 126700 miles and only 16000 of those are mine, in the last nearly seven years, so I should get a low mileage award...
Hi Bezalel
Thank you for your message. Yes after much drama with a leak at the suction side at the compressor, finally got the ac working.
used after market parts including a replacement compressor and did the work myself to keep costs down
The compressor has 3 securing bolts, however in true ml style one is a real sod to get to.
The wacky guages were due to operator error. I had the wrong valves open.
live in Houston so ac is a must!
Still cannot get the check engine/ smog pump issue fixed