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
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