Ram ProMaster City No Blower on Speed 1 & Confusing A/C Issue
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Date: 2025-09-01
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Comments and reviews: 20
MrZ771
Solid call to replace resistor pack. Each switch speed had power but blower was not running at speed 1. I'm guessing the speed one resistor had failed too high to power the blower, but not open. That was enough to call the pack.
I think the weird symptoms were caused by controller trying to detect fan switch setting by measuring blower fan current. When unexpected current was measured, controller gave up and declared the setting was 0. Other controller logic then kicked in and set A/C request to Off because fan setting was declared 0. That happened at all switch settings except 1. Maybe any current at all below some value was enough to call '1' or '2', but any higher current reading had to fit a more precise range
Odd that it could be that picky but also that sloppy. When it was fixed, it never precisely called the fan setting, values were either
'0',
'1' or '2', or
'3' or '4'
and A/C request was On for every position except 0.
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Solid call to replace resistor pack. Each switch speed had power but blower was not running at speed 1. I'm guessing the speed one resistor had failed too high to power the blower, but not open. That was enough to call the pack.
I think the weird symptoms were caused by controller trying to detect fan switch setting by measuring blower fan current. When unexpected current was measured, controller gave up and declared the setting was 0. Other controller logic then kicked in and set A/C request to Off because fan setting was declared 0. That happened at all switch settings except 1. Maybe any current at all below some value was enough to call '1' or '2', but any higher current reading had to fit a more precise range
Odd that it could be that picky but also that sloppy. When it was fixed, it never precisely called the fan setting, values were either
'0',
'1' or '2', or
'3' or '4'
and A/C request was On for every position except 0.
reply
glenforehand
Only test I could think of was depining and install a variable resistor. Maybe I'm exposed to too many GMs but I would have three an amp on andgot a look at the blower motor. Would've sent a camera in the resistor hole to check for trash too etc. I know Eric knows this, lot of guys get burned changing resistors and missing the bad blower/junk in air box that caused the resistor to overheat. Clogged filters too. The motor did sound good but I'd still put an amp clamp on it and run it on low for awhile just to be sure. I'd test vtage and current and play with the control for a while too. Parts guy said he's never sold one, to me that warrants more scrutiny. Honestly though, it's probably just a crappy original resistor.
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Only test I could think of was depining and install a variable resistor. Maybe I'm exposed to too many GMs but I would have three an amp on andgot a look at the blower motor. Would've sent a camera in the resistor hole to check for trash too etc. I know Eric knows this, lot of guys get burned changing resistors and missing the bad blower/junk in air box that caused the resistor to overheat. Clogged filters too. The motor did sound good but I'd still put an amp clamp on it and run it on low for awhile just to be sure. I'd test vtage and current and play with the control for a while too. Parts guy said he's never sold one, to me that warrants more scrutiny. Honestly though, it's probably just a crappy original resistor.
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mrdude2702
Another fine episode from Mr 0 to encourage this DumbA know nothing dude. My 2007 Ram 2500 started doing the same thing last week. I figured it was the resistor but I have not worked on it yet. This episode is encouraging me that I should know the issue. I my situation, blower works in stop 1, 3, and 4 but 2 does not. AC light goes out when I pass through 2. I figured it knows the fan is not running at that speed, so the ac circuit is not complete - thus no ac light. I'm going to guess that resistor has two values. 1 has one value, then 2 might be the second resistor, then third is both and four is no resistor. But why is there even a wire for stop 4 if the resistor is not in the circuit for high speed
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Another fine episode from Mr 0 to encourage this DumbA know nothing dude. My 2007 Ram 2500 started doing the same thing last week. I figured it was the resistor but I have not worked on it yet. This episode is encouraging me that I should know the issue. I my situation, blower works in stop 1, 3, and 4 but 2 does not. AC light goes out when I pass through 2. I figured it knows the fan is not running at that speed, so the ac circuit is not complete - thus no ac light. I'm going to guess that resistor has two values. 1 has one value, then 2 might be the second resistor, then third is both and four is no resistor. But why is there even a wire for stop 4 if the resistor is not in the circuit for high speed
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autorepair
HVAC controller probably measures the voltage drop across the resistor to see where it it shorted to ground (intentionally by switch position. When the resistor is open between positions 1 and 2, the voltage drop really drops to zero, and the controller thinks the AC is shut off. Q. E. D. To troubleshoot this, just purposefully short the pin from position 1 to the position 2 pin. You'll have no speed 1, but the AC would have operated, as it saw the voltage again. SAVE THE OLD RESISTOR to check my theory! Scream at me if I'm wrong, too. I can take it. Cheers, Eric.
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HVAC controller probably measures the voltage drop across the resistor to see where it it shorted to ground (intentionally by switch position. When the resistor is open between positions 1 and 2, the voltage drop really drops to zero, and the controller thinks the AC is shut off. Q. E. D. To troubleshoot this, just purposefully short the pin from position 1 to the position 2 pin. You'll have no speed 1, but the AC would have operated, as it saw the voltage again. SAVE THE OLD RESISTOR to check my theory! Scream at me if I'm wrong, too. I can take it. Cheers, Eric.
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simonparkinson1053
Do a lot of these and the big Promaster (Ducato) in their original Fiat guise.
Generally when these need a resistor, they also need a new connector pigtail too.
Typically the speed 3 and output pins burn up.
On the resistor there are two pins in parallel on the output but only one is wired.
The pigtails have all 5 wires installed so I use both outputs.
That way you're only going to lose one of the speeds next time it fails (and it will - pin size and connection quality are not adequate for the current)
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Do a lot of these and the big Promaster (Ducato) in their original Fiat guise.
Generally when these need a resistor, they also need a new connector pigtail too.
Typically the speed 3 and output pins burn up.
On the resistor there are two pins in parallel on the output but only one is wired.
The pigtails have all 5 wires installed so I use both outputs.
That way you're only going to lose one of the speeds next time it fails (and it will - pin size and connection quality are not adequate for the current)
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rajkumarrudolph399
The resistors overheat and fail when the airflow is poor, more than likely the cabin filter is stopped up. The compressor was inhibited because the resistor was open and there wasn't feedback to the controller through the open circuit. The controller assumed the system was off. Basically, the manufacturer was being cheap by using a single pole switch to justify compressor operation through feedback from the resistor.
Z is Italy, 6 is Australia on the VIN. I use to own a G8 which is basically a Commodore.
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The resistors overheat and fail when the airflow is poor, more than likely the cabin filter is stopped up. The compressor was inhibited because the resistor was open and there wasn't feedback to the controller through the open circuit. The controller assumed the system was off. Basically, the manufacturer was being cheap by using a single pole switch to justify compressor operation through feedback from the resistor.
Z is Italy, 6 is Australia on the VIN. I use to own a G8 which is basically a Commodore.
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faxmen09
22: 46 I think she might be a single hole double donger. yes sir That's what he said folks! . And the reason dealer never sold one, no one but Eric could figure it out or be bothered to go that deep into diagnosis to determine that's what was needed. Had to look up the vehicle and see that it's based on the FIAT Doblo, so a Fix It Again Tony design. Only Eric fixed it this time, Fix It Again Eric. Well done, and a very fortunate customer to have Eric O nearby.
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22: 46 I think she might be a single hole double donger. yes sir That's what he said folks! . And the reason dealer never sold one, no one but Eric could figure it out or be bothered to go that deep into diagnosis to determine that's what was needed. Had to look up the vehicle and see that it's based on the FIAT Doblo, so a Fix It Again Tony design. Only Eric fixed it this time, Fix It Again Eric. Well done, and a very fortunate customer to have Eric O nearby.
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dukwdriver2909
Armies know it takes young soldiers weeks to acclimatize to different temps, artic or desert. Sadly, age does not allow such tolerance so easily, says a really old man who used to be indestrucable. Humans are so arrogant, took animals millions of years to evolve to thrive in different climates. Mrs O needs more screen time credit for keeping your motor running with her multi tasking. Wish we still had Wilbert's type yards here.
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Armies know it takes young soldiers weeks to acclimatize to different temps, artic or desert. Sadly, age does not allow such tolerance so easily, says a really old man who used to be indestrucable. Humans are so arrogant, took animals millions of years to evolve to thrive in different climates. Mrs O needs more screen time credit for keeping your motor running with her multi tasking. Wish we still had Wilbert's type yards here.
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fredtflail
Ive been a technician with Chrysler for almost 12 years and i run into crap like this all of the time especially on Fiats. Chrysler or whatever its called these days has great wiring diagrams but the service data is typically garbage. I find myself just having to figure stuff out. I think of a fuel pressure circuit dtc, nothing in service information mentioned that the fuel pressure regulator on the fuel rail could cause the DTC.
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Ive been a technician with Chrysler for almost 12 years and i run into crap like this all of the time especially on Fiats. Chrysler or whatever its called these days has great wiring diagrams but the service data is typically garbage. I find myself just having to figure stuff out. I think of a fuel pressure circuit dtc, nothing in service information mentioned that the fuel pressure regulator on the fuel rail could cause the DTC.
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mazdaman1286
These resistors fit Alfa, citroen, fiat Peugeot Citroen, dacia, GM etc. Common as muck and cheap as chips. Any problems with ac or blower check the wiring connector for burning and the resistor for dark spots. GM Zafira's had a recall due to cars setting fire, then the recall was recalled. Crappy connections. Kit was new resistor and a connector plug to splice in. All in a space where it was hard to swing a cockroach.
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These resistors fit Alfa, citroen, fiat Peugeot Citroen, dacia, GM etc. Common as muck and cheap as chips. Any problems with ac or blower check the wiring connector for burning and the resistor for dark spots. GM Zafira's had a recall due to cars setting fire, then the recall was recalled. Crappy connections. Kit was new resistor and a connector plug to splice in. All in a space where it was hard to swing a cockroach.
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HyproTube
I don't like to see anyone suffer, but seeing you struggle with what was supposed to be the easy part of this job was very vindicating for me. Almost every time i try to do an easy job there's nearly always a point where a task that's supposed to take 30 seconds ends up taking much longer. As it turns out, even the professionals run into stuff like this!
Great video; definitely learned some things.
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I don't like to see anyone suffer, but seeing you struggle with what was supposed to be the easy part of this job was very vindicating for me. Almost every time i try to do an easy job there's nearly always a point where a task that's supposed to take 30 seconds ends up taking much longer. As it turns out, even the professionals run into stuff like this!
Great video; definitely learned some things.
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RFDarter
16: 17 I would guess it measures the voltage drop to determine the speed position, or maybe use it and the physical position of the knob to validate the position.
Since resistor 1 is broken and on position 2 resistor 1 and 2 are put in parallel and on position 3 resistor 1, 2 and 3 are put in series the controller somehow measures a wrong voltage drop and cant determine the correct position.
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16: 17 I would guess it measures the voltage drop to determine the speed position, or maybe use it and the physical position of the knob to validate the position.
Since resistor 1 is broken and on position 2 resistor 1 and 2 are put in parallel and on position 3 resistor 1, 2 and 3 are put in series the controller somehow measures a wrong voltage drop and cant determine the correct position.
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benb4688
I am guessing that the HVAC module monitors current draw on the ground circuit (since all the grounds go through the havc module) and judges blower position based on amp draw of the blower. That would explain why the HVAC module can't determine exact position but can give a range of position 1/2 or 3/4. Or possibly since blower 1 speed has 2 inputs to hvac module it can monitor voltage drop
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I am guessing that the HVAC module monitors current draw on the ground circuit (since all the grounds go through the havc module) and judges blower position based on amp draw of the blower. That would explain why the HVAC module can't determine exact position but can give a range of position 1/2 or 3/4. Or possibly since blower 1 speed has 2 inputs to hvac module it can monitor voltage drop
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SteveO-001
Understand fully how easy it is to get frustrated pulling apart things with awkward plastic clips. You kept your cool much better than I would - well done! Maybe having a camera recording you is the secret. Last 'problem' disassembly for me, after sweating and swearing for some time, out came the biggest flat blade screwdriver I had and then it was coming apart no matter what.
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Understand fully how easy it is to get frustrated pulling apart things with awkward plastic clips. You kept your cool much better than I would - well done! Maybe having a camera recording you is the secret. Last 'problem' disassembly for me, after sweating and swearing for some time, out came the biggest flat blade screwdriver I had and then it was coming apart no matter what.
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Sean_Diagnostics
Glad to see the american market gets the same common faults. Here in europe the promaster is known as fiat ducato/peugeot boxer/citroen jumper. On these vehicles most of the time speed 4 is the only speed working when the resistor fails. We can order a repair kit from mopar with resistor and wiringloom for the resistor, because the connectors like to melt
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Glad to see the american market gets the same common faults. Here in europe the promaster is known as fiat ducato/peugeot boxer/citroen jumper. On these vehicles most of the time speed 4 is the only speed working when the resistor fails. We can order a repair kit from mopar with resistor and wiringloom for the resistor, because the connectors like to melt
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318ishonk
Looks like Italian electronics design to me.
Apparently this vehicle was produced in Turkey (weird, huh)
In Europe there's a whole world of these cars (different labels for same car, lots of variations) and on the narrow roads in Europe it can make sense.
Not in the land of the free of course, which is why import to the US stopped some years ago.
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Looks like Italian electronics design to me.
Apparently this vehicle was produced in Turkey (weird, huh)
In Europe there's a whole world of these cars (different labels for same car, lots of variations) and on the narrow roads in Europe it can make sense.
Not in the land of the free of course, which is why import to the US stopped some years ago.
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dull_Asian_dad
18: 52 - 24: 44 Aw, man props for your patience, diligence and perseverance. This is where I just don't have the patience to kneel, crawl around, try to look up and remove without damage. I would have been going you muthaf! #$%&)_ (it totally helps) and yanked it out with brute force. Congrats on the mystery diag. Love the super Mario impression.
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18: 52 - 24: 44 Aw, man props for your patience, diligence and perseverance. This is where I just don't have the patience to kneel, crawl around, try to look up and remove without damage. I would have been going you muthaf! #$%&)_ (it totally helps) and yanked it out with brute force. Congrats on the mystery diag. Love the super Mario impression.
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TyphoonVstrom
So this is now a fiat accompli I've seen blower resistors with only two resistor elements- for low, they pair the high and low value resistors together, for 2- high resistor, 3- low resistor. Saves space and cost of an extra resistive element.
So that may be why the system sees low as low/ med when the low setting is selected
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So this is now a fiat accompli I've seen blower resistors with only two resistor elements- for low, they pair the high and low value resistors together, for 2- high resistor, 3- low resistor. Saves space and cost of an extra resistive element.
So that may be why the system sees low as low/ med when the low setting is selected
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N9320H
This also has a bad cooling fan resistor. You hear the cooling fans coming on momentarily. They are energizing off the air conditioning high side switch, and when the pressure drops, they turned back off again they are not working off temperature like they’re supposed to check the Cooling fan resistors.
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This also has a bad cooling fan resistor. You hear the cooling fans coming on momentarily. They are energizing off the air conditioning high side switch, and when the pressure drops, they turned back off again they are not working off temperature like they’re supposed to check the Cooling fan resistors.
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DarenDombroski
I work in South Florida I don't have a problem with the heat I brought a plastic vest with six pockets on the inside and I keep 12 ice bags in the freezer and I switch them out as needed. I also put them in my front pockets they work great. I also have four in the freezer that wrap around my neck
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I work in South Florida I don't have a problem with the heat I brought a plastic vest with six pockets on the inside and I keep 12 ice bags in the freezer and I switch them out as needed. I also put them in my front pockets they work great. I also have four in the freezer that wrap around my neck
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