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.
2002 ML320 with low voltage to AC compressor: climate controls pin-out anyone?
Hey everyone, I've got a 2002 (with updated climate controls) that is having a low voltage signal going to the AC compressor.
Compressor is new. I just got the car and I got it for cheap because the AC wouldn't work. I could see the front of the compressor and it had a busted clutch.
I can turn on the new compressor with a straight wire directly from the battery and everything works fine.
I took it to the shop and they said the compressor is only getting 4 volts and needs 12v to engage.
They then quoted me a $300 labor charge (plus another $500 for new controls) to take apart the dash and test voltage coming out of the controls... I can easily take apart a dash myself, but I was wondering if anyone knew the pin-out on the controls so I can test voltage myself.
I'm picking it up today. I can easily get a $200 set of used controls off of ebay and just replace the one I have in the dash now, but I'm not going to spend that money if the voltage is coming out is fine from the controls and I'm dealing with a frayed wire somewhere...
I'm betting a wiring diagram is on this site somewhere but my searching isn't finding it.
199x - 2001 use these climate controls (the same ones in your PDFs that you attached) that look like this:
While my controls (2002 +) look like the one I linked in the previous post. (ignore the arrows, that was just on the image already and have nothing to do with it)
It was just a question in case you already knew. I'm going to take them out and replace them.
OK... back for more.
So the AAC controls are good. I took them apart and they show no signs of blown fuses.
The system is charged correctly.
The compressor get a 4V signal, not the 12 it needs.
I hot wired the compressor direct to the battery and ran it for 5-10 seconds (until my daughter yelled COOL!!)
I have an iCarSoft reader and the only reading I see that might be of use is the "A9 (AC Compressor) 35%"
not sure if that is in spec or what...
I've read that the pressure/temp sensor can be faulty and not reading right. I'm down to that really... Unless anyone has other ideas?
Please?
update:
there is no sound or vibration at all from that pump in the picture you attached. I even got a long flathead screwdriver and placed it on the pump and put it to my ear with the key to "on" and I could hear the fan blowing full inside, but nothing from the pump.
I checked the codes and the only one (other than a flap code) left after clearing is the B1108
pic attached.
Last edited by ChatWithaNinja; Aug 21, 2018 at 04:48 PM.
update:
there is no sound or vibration at all from that pump in the picture you attached. I even got a long flathead screwdriver and placed it on the pump and put it to my ear with the key to "on" and I could hear the fan blowing full inside, but nothing from the pump.
I checked the codes and the only one (other than a flap code) left after clearing is the B1108
pic attached.
What is the flap code # and what is the description of it?
199x - 2001 use these climate controls (the same ones in your PDFs that you attached) that look like this:
While my controls (2002 +) look like the one I linked in the previous post. (ignore the arrows, that was just on the image already and have nothing to do with it)
It was just a question in case you already knew. I'm going to take them out and replace them.
You said that the fuse only showed voltage on one contact and not the other. That means that the fuse is blown. Something is wrong.
Sorry, no. The fuse block showed voltage on one slot but not the other. 12v current is going to slot 1, then it hits fuse, then it goes out slot 2. when I removed the fuse, that was what I got. 12v current coming out slot 1 and nothing in slot 2 (no short circuiting with 12v going to both end of the fuse).
Sorry, no. The fuse block showed voltage on one slot but not the other. 12v current is going to slot 1, then it hits fuse, then it goes out slot 2. when I removed the fuse, that was what I got. 12v current coming out slot 1 and nothing in slot 2 (no short circuiting with 12v going to both end of the fuse).
I have no idea what you are trying saying, none whatsoever. There is no current involved, just volts.
Do you get 12v when you test both contacts? Yes or no.
So I have been a shade tree mechanic for 30 years and I have messed around with fuses on my life and never once did I realize that there were slots on the top of the fuse that you could check the volts without removing the fuse. I thought you said that I needed to remove the fuse and measure volts going to the fuse from the fuse block which is why I said 1 slot on the fuse block has power the other does not.
thanks for showing me something new! Even though I really should have known it a long long time ago LOL
yes I am getting 12 volts on both side of the fuse
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
