Strange blower motor problem

I have a 2006 Dodge Sprinter 3500. The blower stopped working on all 4 settings when in heat or vent mode however it does blow on all 4 settings when the AC compressor is engaged.

I was fortunate to have parts house friend plug up new blower resistor and also new blower motor which did NOT correct the problem. The results were the same.

The blower works on all 4 fan settings when the ac compressor is engaged but does not blow as hard as it should in any of the 4 settings with ac activated. The blower will not work on any of the 4 fan settings for heat or air circulation via blower / fan control switch. Having tried new blower resistor and also new blower motor with same results I suspect heater control module, however refurbish sprinter electronics man from ebay is not sure it is in the climate control panel.

Heater fan control went out for a day then back on for a day then out again.

I went over all fuses several times and have found none blown under seat or below steering column. I would like to eliminate any other likely problem before concluding it is the climate control panel in the dashboard... Please advise.


Your experience/ knowledge is deeply appreciated.

KY Sprinter

It sounds to me like there may be something going on with the ATC Automatic Temperature Control module logic or connector. The cabin fan control is included in that module.

The ATC module is basically an in/out black box from what I've dug up so far. Some ATC module information is here.
https://sprinter-source.com/forums/showthread.php?t=36931&highlight=atc+module

Some fan circuit information is here.
https://sprinter-source.com/forums/showthread.php?p=273381#post273381

https://sprinter-source.com/forums/showthread.php?p=273578#post273578

Good luck. vic

Thanks Vic,

With key off when I press rest the fan blows as it should.

With key on and compressor activated the fan blows on all 4 settings but does not blow as hard as it should and does not cool as good as it should.

If compressor is off the fan will not blow at all for heat or vent with the key on, on any of the 4 fan settings

I have also installed a new cabin air filter.

befuddled.

KY Sprinter

Go to diagram 8w-42-6 in the thread I listed above.

Splice S201 feeds power to a relay within the ATC module to power the fan speed select switch.

I suspect that you may not always have power to that relay.

Splice S201 is shown on 8w-42-17.

As with some other times I've tried following MB wiring diagrams, I'm not certain exactly what feeds what, but it seems S201 gets power to/from the ATC module, the Heater Timer Aux, the TCS switch [Temperature Control Switch??], and/or the Additional Heat Exchanger Switch [A/C system??]. You can monitor power on the BK/BL/DG wire to see when 12 v power is present to verify whether no power to that internal ATC fan relay is really the problem.

P.S. - I have no idea why the TCS switch is tied to splice S201 and the ASR and the CAB Controller Anti-lock Brake. Added: my TCS acronym guess above is way off... perhaps Traction Control Switch, but why tie ASR/Traction stuff to S201 ATC power?

Added:
Apparently splice S201 is a convenient tap point to acquire fused ignition switch power as shown on schematic #8W-42-17 so it may feed things not necessarily related to the ATC system.



Sorry I can't offer more.

vic

Thanks Vic,

So you think I need a replacement Dodge Sprinter 2500 / 3500 Temperature Control Module or ATC as it is referred to here. I can get one online and or they have folks on ebay who can rebuild my old one.

The module I am referring to sets in the dash and has temperature control knob on left, then fan controller to right and then blend door / recycle cabin air switch, and to right of that is the AC compressor control and rest switch. 4 controls mounted left to right in one electronics module.

I see a used one I can purchase that states it is working equipment and also has no hassle 30 day return policy and also 90 day money back guarantee from a major online auto parts dealer for under $100.00

If I am going to remove the dash I would like to have the replacement part ready to go in and I do not want to pay $400 or $500 if I can get by with a used or refurbished sprinter hvac control module.

The rebuilders also offer an excellent warranty. But you have to wait to get yours back.

I understand that it is rare for one of these to go bad but they do go out... so the guarantee is comforting as I need a good solid replacement module... correct?

I am leaning toward getting the used one and having it ready to swap and test when the dash is removed.

Please let me know your thoughts???

KY Sprinter

A2zsprinter said:

Thanks Vic,

So you think I need a replacement Dodge Sprinter 2500 / 3500 Temperature Control Module or ATC as it is referred to here.

Click to expand...

No.

A2zsprinter said:

Please let me know your thoughts???

KY Sprinter

Click to expand...

I think that you should monitor the voltage of the BK/BL/DG wire (splice S201 ATC module Connector C1 pin #21) during the various operating modes to see when 12v is present to power the fan speed power relay coil. If the 12 volts is not consistently getting to that relay when it should then it is not an ATC module problem.

A2zsprinter said:

... however it does blow on all 4 settings when the AC compressor is engaged.
...

The blower works on all 4 fan settings when the ac compressor is engaged but does not blow as hard as it should in any of the 4 settings with ac activated. The blower will not work on any of the 4 fan settings for heat or air circulation via blower / fan control switch.
...

Click to expand...

The fact that the fan works with the A/C enabled hints that the ATC internal fan relay is ok.

A simple long shot. Have you checked all the fuses in FB#1 under the steering column?

vic

Hi Vic,

Thanks for the information.

This morning I pulled and checked every fuse under the steering column and none were blown,

I also pulled and checked every fuse under the seat. Also checking the two large 30 amp fuses #37 rear window heat which I never use and also #38 a 30 amp for Aux fan air conditioning.

You stated I think that you should monitor the voltage of the BK/BL/DG wire (splice S201 ATC module Connector C1 pin #21) during the various operating modes to see when it is present to power the fan speed power relay coil. If the 12 volts is not consistently getting to that relay when it should then it is not an ATC module problem.

I can get access to a digital volt meter. Where do I find the BK/BL/DG Wire? (black/blue) what does DG stand for? Where is the location where I can access BK/BL/DG Wire connection to place the positive probe to check the voltage?

Is there an easy place to touch the positive probe to check the current or do I need to pull the dash to check this out?

Thanks Mark

DG = Dark Green, but the green isn't always that dark by my eye.

That wire is for certain on the back of the ATC module connector C1 which should be easy to probe.

Another possibility is on the ASR switch near the shift lever. That is dependent on the TCS acronym being Traction Control Switch.

vic

Hi Vic,

I pulled the shifter, ash tray, plastic cup, figured out the left side clip and removed the screws holding the shifter console and did not break anything. Once I got all the plastic parts and besel off I was then able to pull the screws and pull out the ATC module to inspect the wiring and check connections.

Connections seem to be good and I think I found the BK/BL/DG wire (Black/Blue/Dark Green Wire). On the right side the connector with the smaller wires I would guess 18 to 20 color coded wires. On the bottom row the first pin on the left appears to be half black and half blue with a green stripe however like you indicated it is not really all that dark green but is the closest and only apparent match. Is this the wire and pin position you would like for me to test?

I do not have a tester here today they are at my place of work but I will get access to one in the am and follow your test instructions.

My fan blows when AC compressor is on so I will monitor the current flow when ac / blower is operational in all 4 fan settings and also when rest / residual heat and also residual AC is operating which is fan speed 1. Both of which should be producing current on the BK/BL/DG wire and connection pin you refer to.

I will measure the voltage in the various settings and also check for current when the AC compressor is off and blower is on heat / vent for the 4 fan positions and measure current on BK/BL/DG wire for each fan setting during the various operations mentioned.

Am I on the right track? Can you think of any other testing that needs to be done at this juncture other than what I have listed?

I also jumped the gun and ordered a control module from LKQ for $97.00 and have been communicating with speedometerrepairguy.com who rebuilds the ATC's on ebay and offers lifetime guarantee on his refurbished ATC's. He does not think it is in my ATC either but says I got a good buy on the ATC as I have 30 day return and 90 day guarantee it is a used part but marketed as fully operational, speedometer repair guy says it is worth at least $150.00. He has agreed to buy the ATC off me and or purchase my old ATC for $50.00 if it is bad. The auction was closing and no bids so I got the ATC at the lowest possible price for that auction. The cores are hard to come by and most sellers get at least $199.00 for an operational ATC so I think I can resell it but want to be ready for what ever.

Thanks again Vic for your expertise on this, I will look forward to your reply.

Does the first pin lower left on the right hand connector which connects behind AC compressor switch, the connector with the large bundle of small gauge wires sound like the pin I need to monitor?

The black blue is not candy striped, it is more straight up and down black and dark blue with the green band about every half inch sorta avocado in color.

From what I gather we are checking the fan current into the ATC fan relay and if it is there when fan is working and is not there when fan wont blow then the problem is some where else.


Much Appreciation,
KY Sprinter

A2zsprinter said:

Hi Vic,

On the bottom row the first pin on the left appears to be half black and half blue with a green stripe however like you indicated it is not really all that dark green but is the closest and only apparent match. Is this the wire and pin position you would like for me to test?

Click to expand...

That sounds like it. 16 AWG wire Pin #21 on Connector C1.

A2zsprinter said:

...
AC is operating which is fan speed 1. Both of which should be producing current on the BK/BL/DG wire and connection pin you refer to.

Click to expand...

Ok. That helps to give direction. There will not necessarily be power on Pin #21 when the fan is running on speed #1 lowest speed.

The internal fan relay is needed for all 4 speeds. There is a pin which feeds only fan speed #1 (slowest) for REST [and with A/C enabled]. That connection doesn't need the ATC module internal main fan relay to run the fan. Your fan is running via that Speed #1 separate circuit.

Added. The control is designed to operate the fan on speed #1 whenever the A/C is enabled. That helps to assure that there is always some air flow over the evaporator coil. That would help prevent icing of the evaporator coil.

See BK/VT (Black/Violet) wire. "B" triangle in this diagram.

A2zsprinter said:

I will measure the voltage in the various settings and also check for current when the AC compressor is off and blower is on heat / vent for the 4 fan positions and measure current on BK/BL/DG wire for each fan setting during the various operations mentioned.

Am I on the right track? Can you think of any other testing that needs to be done at this juncture other than what I have listed?

Click to expand...

With the fan only running on speed #1 it should be enough to just check for 12 v on the BK/BL/DG wire.

A2zsprinter said:

From what I gather we are checking the fan current into the ATC fan relay and if it is there when fan is working and is not there when fan wont blow then the problem is some where else.
...

Click to expand...

Correct. If you find 12 volts on the BK/BL/DG Pin #21 wire and the fan will not operate on all speeds then that indicates your internal fan relay coil is getting proper control signal power, but is not powering the fan switch for whatever reason. (It could be a bad coil, loose connection, bad contacts... who knows?) At any rate the solution at that point is to install the replacement ATC module.

A DIY repair could be to replace the internal relay with an external relay, but that involves circuit board level modification. You have the part so you should just use it.

vic

Added:
For future reference:

A quick fan motor check if the Cabin Fan will not operate on all speeds.

Enable REST or your A/C system. If the Cabin Fan operates on low speed, but doesn't respond to the other speeds it is likely an ATC module internal fan relay problem. It is NOT the resistor pack because the REST speed #1 needs the resistor pack to be complete for that speed to operate. (It uses all the resistors in series for the circuit.)

Hi Vic,

I ran the tests on the BK/BL/DG wire.

With the Key ON and the AC compressor on, I got 12.4 volts on all 5 fan speed settings 0 through 4.

With the key On and AC compressor off, The heat / vent blower test I got 12.54 on all 5 fan speed settings 0 through 4.

On residual heat / Rest switch ON I got 0 volts on all 5 fan speed settings 0 through 4.

I want to note that with van parked and key on and with AC compressor on the fan is blowing some on 0 at what appears to be the same speed as fan speed 1 and when switched to 2 I cannot tell if it speeds up it seems like it does, 3 definitely speeds up more and 4 is a higher speed still.

On residual heat the same fan speed results were observed... the fan is blowing some on 0 at what appears to be the same speed as when I switch to fan speed 1 and when switched to 2, I cannot tell if it speeds up it seems like it does, 3 definitely speeds up more and 4 is a higher speed still. Residual heat I thought was suppose to blow the same speed (fan speed 1) one no matter what setting the fan control is on.

Your thoughts Please...

I read your last reply and want to say thanks.... Yes from the test results it sounds like the ATC, I will not have the part until next week but it has been shipped. I will watch for comments and post back.



Thanks,
KY Sprinter

A2zsprinter said:

Hi Vic,

I ran the tests on the BK/BL/DG wire.

With the Key ON and the AC compressor on, I got 12.4 volts on all 5 fan speed settings 0 through 4.

With the key On and AC compressor off, The heat / vent blower test I got 12.54 on all 5 fan speed settings 0 through 4.

On residual heat / Rest switch ON I got 0 volts on all 5 fan speed settings 0 through 4.

Click to expand...

With a nominal 12v on the BK/BL/DG wire the internal relay should supply power to the fan switch, the resistor and on to the cabin fan motor. At this time I wouldn't consider tenths of a volt significant data. If you are not getting full speed out of the fan then it can be bad connections anywhere, or maybe a bad internal relay or other problem within the ATC.

A2zsprinter said:

I want to note that with van parked and key on and with AC compressor on the fan is blowing some on 0 at what appears to be the same speed as fan speed 1 and when switched to 2 I cannot tell if it speeds up it seems like it does, 3 definitely speeds up more and 4 is a higher speed still.

On residual heat the same fan speed results were observed... the fan is blowing some on 0 at what appears to be the same speed as when I switch to fan speed 1 and when switched to 2, I cannot tell if it speeds up it seems like it does, 3 definitely speeds up more and 4 is a higher speed still. Residual heat I thought was suppose to blow the same speed (fan speed 1) one no matter what setting the fan control is on.

Your thoughts Please...

Click to expand...

I too would expect only speed #1 on REST. What you observe may be related to the failure mode of whatever is going wrong. If the speed switch has some bridging during position change that could be shorting out a resistor during switching, but that is a stretch.

The next move for me would to probe the voltage at the cabin fan itself to see how much it is changing. While you are into that area another quick test would be to jumper 12 volts directly to the cabin fan motor to verify that it will run at full speed. It is possible that marginal bearings, (You said earlier that you tried another blower motor.) a poor ground, high resistance connection, or other problem is keeping the cabin fan from attaining full speed. With 12 v on the BK/BL/DG and no fan speed response it still points back to the internal ATC relay with the possible exception of the odd changing speeds that you notice.

vic

Thanks Vic,

The used ATC I purchased has everything working except the light on the temperature control. I forgot to test the lighting before I replaced the dash. I checked every thing else three and 4 times but forgot about lights. The blower speed is back up like it should be on AC and blowing great on heat and vent to.

Thanks for your help on this electrical issue.

KY Sprinter

Good to hear you're back in service.

A2zsprinter said:

Thanks Vic,

The used ATC I purchased has everything working except the light on the temperature control.
...

KY Sprinter

Click to expand...

This may not apply, but...

Are you only using DRL's? The stalk switch needs to be in one of the exterior lights on position for the entire dash back lighting to operate. That includes the ATC unit. The DRL Daytime Running Lights only illuminates the dash gauge cluster and inset. All the other dash lights will remain off until the stalk switch is operated.

vic

Sorry to thread-jack this, but I too wanted to say Thank You for the REST fan diagnosis...

I have a similar issue:
Fan only on 4 when I bought my 3500 last August. - replaced resistor, OK.
3 months later, blower stopped working- Replaced blower, OK.
Last month blower stopped working again- removed, tested, works great. Installed a new Climate control unit, did the REST test and the blower works, nothing on speeds 1-4.

Is the relay for the blower on the panel under the driver's seat? (Position 4 if I remember correctly?)

Thanks in advance! -Dave

I have the exact same issue...glad I came across this thread!!

Thread Ressurection: how about if you have a new blower and resistor, no blown fuses and no fan speeds, rest button ac or heat selected

Further info, scan tool says blower stage 1 short, error b1007 in hzr module

another resurrection of this thread..same symptoms as above, but intermittent,
rest works when van is hot, ie,hot air bowing from vents,but i heard a clicking, like turn signal relay behind the ATC when i tried rest button after van cooled
same blower stage 1 code b1007-005
atc fan relay??