05 T1N ATC Relay Replacement Guide (For No Fan Speeds)

Thenewguy

05 Sprinter
TLDR; This is for no fan speed (not the single fan speed resistor pack issue), after checking the blower is operable by jumping 12v to it to verify it is an AC ATC issue.


This post will highlight the symptoms, and parts necessary for repair.

After purchasing a new ATC module late last year from Module Repair Pro in Van Nuys, CA because of an AC issue, I wound up with a new module with a warranty for around 150 dollars. Alas, the issue was my AC system and not the ATC. Three weeks ago I went to flick the heater on and noticed no fan controls, not a 'one fan setting' as read in relation to a failing Resistor Pack, but instead absolutely no fan. I decided I'd throw my money at a cheap resistor pack and see if fixed anything, but that didn't resolve the issue.

I decided after ticking that off the list that I'd call Module Repair Pro and bring the ATC in under warranty. I drove around an hour and a half to get there, pulled the module out and went in. Their "tech" pulled it apart, and found that the fan relay had burnt out (I'll list this down below). I was happy to hear that the issue was apparent, and then the owner proceeded to tell me that it would be $100 dollars to replace, and that the warranty was only for issues that were caused at their fault. I don't know what the hell that means. He says he needed to pay his technician to fix it and $100 was the cheapest for labor and the relay. He showed me the relay that was burnt out, and I proceeded to tell him that I was too broke to pay that much, but the truth is... I'm just cheap. He even tried to lower the price to $75, but I was a little too bitter about the entire ordeal, and it should have been covered by the warranty. Anyways, I am unsure how it wouldn't be the fault of the components on the board, I do not have any shorts in the wiring or anything like that. Sounds like a bait and switch to me. Buyer Beware.

Needless to say, I peeled the dumb 'warranty void if removed' sticker off when I got home, and ordered the new relay. Lo and behold, you can get a pack of these relays for like $10 from China, or if you wanted it sooner you can buy it from the one dealer on ebay in the US for 12 bucks for a single one. Since I'm impatient, I resorted to the latter.

When I received it I just used my soldering iron and suction tool (included in a cheap soldering kit from Alibaba from a few years ago) to release the old relay from the board, used a little bit of force and it came out.

Placed the new relay in, soldering a pin to hold it in place and proceeded to get finish the job.

As concerned as I was about my inability to solder on a circuit board, I was more concerned that maybe the part mentioned at the module shop was incorrect, and that I would need to order another relay or something. To my surprise, I reinstalled the unit in my van, and it WORKED!

You can do this easily, and all it cost me was 12 dollars plus the time to remove and install the unit.

Tools Needed:
Soldering Iron
Suction Tool for Solder
Relay v23076-a3001-c132 (Found mine on Ebay)
Patience

I cannot stress the last part enough, the module isn't super delicate, but it is very possible to hulk out and snap some of the little clips that hold the unit together or the clips holding the board down to the housing.

The relay can only fit in one way on the board.

Mind that spring in the fan position selector in the middle too, sit it aside and don't lose it.

Once again, this is only to fix ALL speeds not working after verifying that the blower still functions by jumping it.

Good luck!

One picture of the relay attached during the operation. Pretty simple.
 

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jrod5150

Well-known member
"I'm just cheap" had me rolling :ROFLMAO:. I haven't had a bad fan relay internally in the ATC module. Gino is a really good guy I'm surprised you weren't able to come to an agreement. Thanks for posting the relay information
 

Thenewguy

05 Sprinter
"I'm just cheap" had me rolling :ROFLMAO:. I haven't had a bad fan relay internally in the ATC module. Gino is a really good guy I'm surprised you weren't able to come to an agreement. Thanks for posting the relay information
Yea, I'm sure everyone's experiences are different. To be honest, where else are you gonna find a place that can fix an atc for our sprinters locally?

Just think it's funny to put a warranty void if opened sticker on the item when the warranty doesn't seem to exist. :LOL:

Either way, because of my thrifty ideals, I got to learn something and since I couldn't find anything about this on the forums, I get to contribute something as well.

All's well that ends well.
 

autostaretx

Erratic Member
Question: which half of the relay died?
There's the COIL (which the AC controller powers up) ... and *that* should have been covered by the warranty.
and then..
There are the CONTACTS (the path power uses to reach the fan motor) .... if those are what died, then indeed, it was external factors that took out the relay.

You can test the coil with an ohmmeter ... a blown coil will have infinite resistance.

--dick
 

Thenewguy

05 Sprinter
Question: which half of the relay died?
There's the COIL (which the AC controller powers up) ... and *that* should have been covered by the warranty.
and then..
There are the CONTACTS (the path power uses to reach the fan motor) .... if those are what died, then indeed, it was external factors that took out the relay.

You can test the coil with an ohmmeter ... a blown coil will have infinite resistance.

--dick
Darn it, dick. I already tossed the relay out. I suppose I will find out if it happens again.

I just struggle to understand what changed in my system to cause an issue like that.

Do you know what kind of external issues could cause that? Cheap resistor packs?
 

220629

Well-known member
Thanks for the information.

Relay v23076-a3001-c132

The specification sheet indicates 90 ohm (listed 1.6 watt) coil and 45 amp contacts. I had thought that an external automotive 86 relay could be cobbled on. The 86 relay has coil 75 ohm (typical) and contacts 40 amp. Any extra 86 coil load is probably ok. It's a bit of a risk with the contacts being rated less than 45 amps. That said, if a socket or slide connectors are included with the cobbled in 86 relay replacement would be easy (if ever even necessary).

vic
 

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autostaretx

Erratic Member
Do you know what kind of external issues could cause that? Cheap resistor packs?
How long a list do you want?
The resistor pack is the last thing that i'd suspect ... unless the "naked" temperature-fuse hanging on the outside contacted frame metal (dead short).
My usual three suspects for contact damage are:
(a) contamination in the relay itself .. leading to pitted/corroded contacts which will then further self-destruct from arcing (as less good metal is trying to carry the currents)
(b) blower motor problems: shorted (between each other) commutator segments (possibly due to electrically-conductive "dirt" (or shards of wearing brushes and segments)
(c) wiring harness damage (rodents? the infamous "bend" behind the fuel filter?) ... intermittent short circuits drawing excessive currents through the contacts
... or a combination of the above (Murphy's Law can strike twice or thrice)

The resistor pack *lowers* the current draw through the relay contacts. Speed 4 (max) is the highest load on the contacts, and the minimal use of the resistors. There is the chance of the REST or Aux Heat functions having messed up and drawing power, but that would take sleuthing through the AC controller. REST and the Aux heater do a "sideways" tap into the "speed 1" section of the circuitry. That's the "C220" connection in the following diagram:

BlowerChoices.jpg

--dick
 

Thenewguy

05 Sprinter
Well, I guess only time will tell at this point. If it happens again, then we will know it is one of these outside factors. At that point, I suppose I'll go on the hunt. Although, I do think it's possible (small possibility) that I did something weird with the blow when I was reinstalling it again and again during my injector removals along with that entire filter assembly, so there is a small chance it won't actually happen again.
 
How do I bench test this relay in the ATC PCB? I have benchtop 12V and a good multimeter, just not the knowledge to know how to test a relay inside a PCB...
 

autostaretx

Erratic Member
How do I bench test this relay in the ATC PCB? I have benchtop 12V and a good multimeter, just not the knowledge to know how to test a relay inside a PCB...
The relay may well use lower voltages for its coil (switched by transistors or integrated circuits, not simply "12v")

It may have its coil voltage (or resistance) printed on the relay.
To avoid damaging the rest of the board, you're safest unsoldering it before testing.

--dick
 

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