Sprinter A/C not working, could use professional assistance.

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WrenchTurnerDave

New member
You know how sometimes, you'll work on something so long that you will actually neglect to go back and check the little obvious things because you're stunned stupid by this machinery?
This has happened, so, if I've overlooked something stupid, sorry. Here it is;

2006 Dodge Sprinter
2.7L L5 with 387,000 miles
Automatic transmission

I'm trying to deal with the A/C. The boss man got it and decided he wanted to fix the A/C.
I've been informed that there was a tech that messed with it for many hours before giving up, so now it's my job (problem).

I hooked up manifold gauges and a vacuum, vacuumed it and it held steady at 29 in Hg for an hour before I unhooked the vacuum. I started trying to put R-134a into it and the clutch wouldn't kick on. I found on the compressor someone has cut the harness off and put a butt connector on it for some reason. I jumpered behind the connector to B+ and the clutch engaged, and started taking freon.

I got less than a pound in it and my pressures started worrying me, so I immediately killed it and backed off. I've checked for the MYTHICAL A/C CLUTCH RELAY to no prevail. I have yet to find a relay in this thing that goes to the clutch. By the way, I don't have rear A/C or a roof unit with anything in it. This is a cargo freight liner with a headache gate. I'm only working on front A/C. Anyway, no relay found. Found the one for the fan, and other A/C "related" components underneath the drivers seat. Not on the vertical panel with a nice neat cover, but under the one that you have to remove the seat to see, where the module is. Anyway, they all work, and don't go to the clutch.

I also tried to find a low side pressure switch, and all I came up with (I'm not familiar with Sprinters or Mercedes platforms for that matter) was a pressure switch transducer on top of the accumulator. It has three wires going to the connector. A 5V reference, a signal, and a ground. I checked the wiring and I had what I needed.

I couldn't find an ohm specification for this sensor, so I'll tell you what I found.
615 ohms between 5V and ground.
612 ohms between signal wire and ground.
These readings are with harness disconnected.
Also, to me this is weird, I couldn't get the clutch to engage by jumpering the terminals of the harness to the pressure switch. If I unhooked it the fans would come on, but no jumper would engage clutch. I can only get it to engage with a jumper.

Also, pressure readings.
While charging, with it about 60 degrees out today, my low side, with the compressor running was about 40 PSI and my high side was about 150 PSI, already not cool. The high side line was hot and the low side was ice cold. I had heat coming out of the front dash vents, but on the top (A/C only vents) I had 40 degree air. Front dash vents were 80 degrees.
So, un-jumpered the compressor.

Whoa.

High side pressure almost immediately shot up to almost 300 PSI and low side pressure shot up to almost 100 PSI. I shut the vehicle down and watched. The high side and low side equalized at 80 PSI and there it sat. I'm just glad the valve for the can was closed and it didn't blow the hell up. I should also mention that with the compressor engaged the low side pressure was falling slightly, which I thought indicated the compressor was working, but that's not a guarantee...

Anyway;
Clutch won't automatically engage
Only top vents blow cold air, front vents blow hot.
Weird ohm readings from sensor switch.
Someone has tinkered (cut-spliced) compressor wiring.
Can't find relays related to problem area.
Pressure readings are ridiculously high on both sides.

I'm a tech, I have some equipment. I'm trying my best. I'm sorry to bother you guys with this stuff, but I'm at my wits end with this, hoping it's something simple.

I may or may not have forgotten something.

I'm sorry this is such a long post, but I'm hoping I've given you enough information to be able to narrow it down since you are the Sprinter professionals.
I can take pictures of anything you need tomorrow, as well as temperature readings, video, whatever you need. Just let me know.

All help is appreciated and I will be checking back to respond to questions.

Thanks.

WrenchTurnerDave
 
cahaak

cahaak

New member
I think maybe Dennis will be along with some more technical details of the system, but here are a few things you need to do. First, check the cabin air filter and make sure that it is good and replace as necessary. You need to make sure that you have the correct air flow over the evaporator coil. Also, you can download the service manual here on the forum for the 2006. Do a search in the T1N section for it. The far top vents are only outside air and are routed different than the dash vents. The total charge on the system is only something like 1 lb 9 oz - not that large and it is very sensitive to the charge level. I can't comment on the relays or the specifics of the fill approach, but if your clutch is engaging and your system is sound and not wet (dryer may need replacing), then it sjhould work fine with the correct charge.

Chris
 
L

lindenengineering

Well-known member
WrenchTurnerDave said:
You know how sometimes, you'll work on something so long that you will actually neglect to go back and check the little obvious things because you're stunned stupid by this machinery?
This has happened, so, if I've overlooked something stupid, sorry. Here it is;

2006 Dodge Sprinter
2.7L L5 with 387,000 miles
Automatic transmission

I'm trying to deal with the A/C. The boss man got it and decided he wanted to fix the A/C.
I've been informed that there was a tech that messed with it for many hours before giving up, so now it's my job (problem).

I hooked up manifold gauges and a vacuum, vacuumed it and it held steady at 29 in Hg for an hour before I unhooked the vacuum. I started trying to put R-134a into it and the clutch wouldn't kick on. I found on the compressor someone has cut the harness off and put a butt connector on it for some reason. I jumpered behind the connector to B+ and the clutch engaged, and started taking freon.

I got less than a pound in it and my pressures started worrying me, so I immediately killed it and backed off. I've checked for the MYTHICAL A/C CLUTCH RELAY to no prevail. I have yet to find a relay in this thing that goes to the clutch. By the way, I don't have rear A/C or a roof unit with anything in it. This is a cargo freight liner with a headache gate. I'm only working on front A/C. Anyway, no relay found. Found the one for the fan, and other A/C "related" components underneath the drivers seat. Not on the vertical panel with a nice neat cover, but under the one that you have to remove the seat to see, where the module is. Anyway, they all work, and don't go to the clutch.

I also tried to find a low side pressure switch, and all I came up with (I'm not familiar with Sprinters or Mercedes platforms for that matter) was a pressure switch transducer on top of the accumulator. It has three wires going to the connector. A 5V reference, a signal, and a ground. I checked the wiring and I had what I needed.

I couldn't find an ohm specification for this sensor, so I'll tell you what I found.
615 ohms between 5V and ground.
612 ohms between signal wire and ground.
These readings are with harness disconnected.
Also, to me this is weird, I couldn't get the clutch to engage by jumpering the terminals of the harness to the pressure switch. If I unhooked it the fans would come on, but no jumper would engage clutch. I can only get it to engage with a jumper.

Also, pressure readings.
While charging, with it about 60 degrees out today, my low side, with the compressor running was about 40 PSI and my high side was about 150 PSI, already not cool. The high side line was hot and the low side was ice cold. I had heat coming out of the front dash vents, but on the top (A/C only vents) I had 40 degree air. Front dash vents were 80 degrees.
So, un-jumpered the compressor.

Whoa.

High side pressure almost immediately shot up to almost 300 PSI and low side pressure shot up to almost 100 PSI. I shut the vehicle down and watched. The high side and low side equalized at 80 PSI and there it sat. I'm just glad the valve for the can was closed and it didn't blow the hell up. I should also mention that with the compressor engaged the low side pressure was falling slightly, which I thought indicated the compressor was working, but that's not a guarantee...

Anyway;
Clutch won't automatically engage
Only top vents blow cold air, front vents blow hot.
Weird ohm readings from sensor switch.
Someone has tinkered (cut-spliced) compressor wiring.
Can't find relays related to problem area.
Pressure readings are ridiculously high on both sides.

I'm a tech, I have some equipment. I'm trying my best. I'm sorry to bother you guys with this stuff, but I'm at my wits end with this, hoping it's something simple.

I may or may not have forgotten something.

I'm sorry this is such a long post, but I'm hoping I've given you enough information to be able to narrow it down since you are the Sprinter professionals.
I can take pictures of anything you need tomorrow, as well as temperature readings, video, whatever you need. Just let me know.

All help is appreciated and I will be checking back to respond to questions.

Thanks.

WrenchTurnerDave
Click to expand...
Dave
I have read your text--I will have writer's cramp answering it all!
Give a call in the AM on 720 344 1877.
Denver time that is after about 8,30 a.m.
Say you are a fellow tech and don't sound like a banker or a salesman because the petty one in the back office screens calls from men in suits!:laughing:
Dennis
 
W

WrenchTurnerDave

New member
I'll definitely be doing that.
What if I'm a tech wearing a suit? Will I be screened?
What if I'm a tech and I killed a suit and I'm wearing a suit suit?
 
W

wires

Member
WrenchTurnerDave said:
While charging, with it about 60 degrees out today, my low side, with the compressor running was about 40 PSI and my high side was about 150 PSI, already not cool. The high side line was hot and the low side was ice cold. I had heat coming out of the front dash vents, but on the top (A/C only vents) I had 40 degree air. Front dash vents were 80 degrees.
Click to expand...
In my experience hot air (above ambient temperature) blowing from the dash vents indicates that the heater core has hot engine coolant circulating through it. The heater control valve is open when unpowered and sometimes will stick open. My Sprinter would blow hot air on a hot restart for 5-10 minutes and had bad temperature regulation when using the heater. Replacing the heater control valve fixed that

It is possible the previous repair was a misguided attempt to "overpower" the heater with the A/C. That will never happen...
 
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WrenchTurnerDave

New member
Spoke to Dennis a few hours ago and got a plethora of useful knowledge.

I was guided on how to do a FULL COOL TEST and disconnected the binary switch on the accumulator that turns on
the fans. I jumpered the compressor, left the fans running, and was able to get it to take 1.9 pounds AND all with proper
pressure readings across the gauges.

Got temperatures of about 37 degrees out of the vents with ambient temperatures of 62 degrees in my shop.

The only problem is that the compressor will not self-engage once I take off the jumper. That is all that remains
in the remedy of this problem.

As I said before, someone has previously tinkered with the wiring on the compressor. It has a butt connector going to
a wire right behind the pulley, and with the vehicle running I get right at 14 VDC out of it, but the compressor still doesn't
engage, which is weird because when I jumper this same wire to a 12V battery, without the wire hooked to the butt connector,
it works fine.

What do I need to check or do to figure out why the compressor will not engage the clutch on it's own?
 
W

WrenchTurnerDave

New member
UPDATE: The culprit seems to be bastardized wiring. I'm trying to figure out how it used to go. Someone did a number on it.

If I can figure out how it used to go I should be able to fix it. If not, I'll have to replace the compressor because when they bought
wire cutters from the parts house, they didn't come with training, skills, or common sense.
 
L

lindenengineering

Well-known member
Dave
Go to pin #12 on the controller its a direct feed to the A/C clutch.
Pull up shop key to see the layout.
I would jumper the controller contact to the clutch and see if you have engagement.
Don't overlook clutch plate clearance and amps to pull the clutch in.
Engine ground strap and poor clutch winding insulation might be causing a huge amp drain on the system.
Dennis
 
W

WrenchTurnerDave

New member
I'll upload pictures tomorrow or Saturday to show you guys what I mean about the wiring. If I'd had another compressor from that van
to look at I'd have solved this problem long ago.
 
W

WrenchTurnerDave

New member
Okay guys, I was out of town this weekend but I just got back and started messing with the Sprinter again.

Regardless of whether the wiring "would have" worked or not, I replaced the bastardized compressor with a
new compressor with factory wiring.

I also installed a new thermostatic expansion valve and accumulator as per warranty standards for the compressor.

The a/c works quite well, but I am still having an issue. The compressor will not command on by itself. It MUST be
jumpered to have the clutch engaged.

Just in case you are going to ask, here is my temperatures;

with compressor running (jumpered)
and fan running (binary switch unplugged)

above thermostatic expansion valve
high = 85
low = 97

below thermostatic expansion valve (accumulator side)
high = 106
low = 51

ambient temperature = 72

low side pressure = 33 psi
high side pressure = 245 psi

air coming out of vents between 28 and 35 degrees

I know this has to be just an amperage problem, there is no way this compressor just plain isn't working.

Dennis, I have not checked number 12 on the controller. I'm wondering if you are wanting me to do this
for a continuity test or if this is a process of elimination for something else.

If you have any ideas I'd love to hear it.
 
W

WrenchTurnerDave

New member
This problem is electrical, I'm fairly sure.

The voltage I am getting from the wire that runs to the compressor is negative voltage. I'm blanking on what that could mean, but

when jumped to the positive terminal everything works great.

Only when jumped. Why the hell is this thing not commanding itself on?
 
sikwan

sikwan

06 Tin Can
WrenchTurnerDave said:
Dennis, I have not checked number 12 on the controller. I'm wondering if you are wanting me to do this
for a continuity test or if this is a process of elimination for something else.
Click to expand...
The schematics show pin 12 from the Automatic Temperature Control Module...
atcm.JPG
...connect directly to the compressor clutch.

Do a continuity test to see if you have that connection; pin 12 to the compressor clutch.

If that is verified to be good, then you either need to fix or replace the Automatic Temperature Control Module.
 
W

WrenchTurnerDave

New member
Okay guys, so here it is. God, I hope Dennis comes by and sees this one.


So, I located the wire that goes directly to the clutch under the drivers seat. I tested for continuity, and...nothing.

I ran a jumper wire from that wire to the compressor clutch, started the van, and all was well. The clutch engages and
disengages, the fans start and stop, and the a/c is absolutely ice cold.

Wonderful I thought. So, I ran a new wire, with proper routing, from the old wire and to the compressor. Worked beautifully.

Until, I turned off the van. I turned off the ignition and removed the key, and the van just kept right on running, pumping
out arctic like temperatures out of the dash. I thought that was weird, since it's never done that before, so I figured since
the air conditioning was what I was working on, I may as well check that first. There was no key in the ignition, it was in my
hand, switch was off, van was running. I reached over and turned off the a/c (snow flake) button and the van immediately
turned off.

After experimenting with it for a few minutes here is what I can tell you;
It has never done this before.
It ONLY does it with the a/c on, and with recirculate on. If recirculate isn't turned on, it won't do it. If recirc is on
but a/c isn't on, doesn't do it. Only does it with recirculate and a/c on, then turn van off, then press a/c to actually
kill van.

What kind of Jimi Hendrix stuff is this?

EDIT: Oh yeah, I forgot to tell you guys the best part. While routing the new wire, I realized why the old one didn't have continuity.

Some idiot must have seen it had voltage and decided it was there for his personal use, because he/she cut the wire and used a piece of an extension cord to wire up the GPS unit in the van, supposedly so they could have the accessory hole for their phone or vibrator or something, and then I'm guessing, pure speculation, they realized their GPS was working like a badass but they'd lost a/c, I'm hoping this was done during winter months, and then they bastardized the wiring on the compressor and the clutch coil trying to bypass whatever was messed up instead of realizing they cut it for a GPS.

I don't know, I just don't know.
 
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