Where is the heater fan relay?

diesellover

New member
The fan works, I can short circuit it and it will run smoothly and quietly. The fuse is good. I heard something click under the dash when it stopped blowing, then it worked for a few more days, then it clicked again and the fan hasn't worked since.
 

220629

Well-known member
The relay is included within the ATC Automatic Temperature Control which is the module that has the temperature dial, fan wheel switch, duct select, etc. built in.

In my service manual wiring 8w diagrams

Air Conditioning-Heater

8w-42-6

vic
 

NelsonSprinter

Former Nelson BC Sprinter
The fan can also stop working if the resistor block in the fan shroud has blown . It is behind the foam up near the back of the hood, roughly where the glovebox/ passenger airbag would be from the engine side.
 

diesellover

New member
I found the resistor block and it tested fine. I pulled the control panel off the dash, looking for something that looks like a relay now...time passes...ok I found it. Hot-wired the wiring harness and the fan blows on all speeds. Now does the little thing come off or do I have to replace the entire control panel?
 
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diesellover

New member
FOUND IT!!
WARNING: READER BEWARE
This is typical German engineering. Just disconnect the wiring harnesses and the two cables and send it to someone who specializes in rebuilding these or buy a new one. You WILL break the 3 tiny feet of the switches off getting to the circuit board. The relay is soldered to the bottom of the board.
 

bc339

New member
Here's an image of the ATC board. Feeling up to a challenge a few months back, I had my ATC apart for troubleshooting. The fan relay is the larger black cube, the A/C is controlled by the smaller one. Both are soldered onto the board. The knob mounts can be removed without damage by carefully squeezing the locking tabs that hold it to the board together - you'll need long tweezers or hemostats to reach a few of them.

My A/C would not engage and I thought it would be the relay, but troubleshooting proved the relay was working. It turned out to be one of the four resistors that are surface mount soldered to the board that had failed.

Bruce
 

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220629

Well-known member
Now that I have it apart....where do I get the relay V23076A3001D142 so I can put this back together?
Based upon communication with BC339 Bruce, there didn't seem to be a readily available direct replacement.

The discussion moved to a DIY repair by replacing the relay with an externally mounted one, but it turned out his relays were OK.

A suitable relay wasn't identified because that was not the solution at the time. I think that a DIY repair could easily be an external wired/mounted relay. That likely gives the additional benefit of selecting a unit with a higher rated contact.

vic
 

bc339

New member
Goggle searching turned up this: http://www.eciaauthorized.com/search/1-1393277-7

Here's the data sheet for the relay.

It looks like the Schrack part is the same as Tyco. The manufacturer party number is 1-1393277-7.

The smaller relay that's in the A/C circuit is difficult to source in the US, I didn't try overseas as I found it was good.

The data sheet will give you a schematic of the relay - this could be used to find a suitable substitute or used to make an external mounted relay.

Bruce
 

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220629

Well-known member
Can you recommend a suitable remote mounted relay?
It looks fairly standard as to 12 volt coil and either N.O. (Normally Open) contact configuration or 1 ea. N.O./1 ea. N.C. (Normally Closed).

The 87 style relay should sub for N.O.

The 87a style for N.O./N.C.

Those are both fairly standard automotive relays. They do come in different contact ratings though.

Some info is here.

https://sprinter-source.com/forums/showthread.php?p=221060#post221060

Edit: correct size slide-on connectors with suitable insulation will work if a socket isn't available.

vic
 
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Gulf SV

Kevin Burns
It looks fairly standard as to 12 volt coil and either N.O. (Normally Open) contact configuration or 1 ea. N.O./1 ea. N.C. (Normally Closed).

The 87 style relay should sub for N.O.

The 87a style for N.O./N.C.

Those are both fairly standard automotive relays. They do come in different contact ratings though.

Some info is here.

https://sprinter-source.com/forums/showthread.php?p=221060#post221060

Edit: correct size slide-on connectors with suitable insulation will work if a socket isn't available.

vic

By your diagram, vic, those are standard auto relays using 1/4" connectors. The housing mounts for those are very common as are the snap-in female connectors. If diesellover wanted to be real sanitary with an install, he could run wires down the the seat base and order a plug from MB—they are cheap. The plug will drop right into the relay block in the seat base,
 

diesellover

New member
GREAT! Thanks for all the help everyone. I was able to unsolder the relay, solder in wires and mount the relay remotely. Note that there are three posts marked #4. These are all common and two of them are used to anchor the relay to the circuit board. You need only run a wire from one of these so this ends up being a 4 wire relay.
 

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