Updated resistor pack failure? - LotusTalk - The Lotus Cars Community
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post #1 of 17 (permalink) Old 11-19-2017, 09:11 AM Thread Starter
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Updated resistor pack failure?

I have the classic signs of a failed resistor pack:

'07 Exige S
No blower function at 1,2,3-settings.
All fuses are good.

I pulled the heater core and fan only to find...that I appear to have an updated resistor pack!

In the first picture, the brass-colored resistors of the updated resistor sit behind the upper right wire.

In the second picture, I noticed that the connector to the heater blower looks a but burnt.

I tested the blower motor w/ 12v and it functions.

Next I will double-check all the fuses and the continuity of the resistors. If I get continuity, I'll check for voltage from the supply harness.

Has anyone else had a no-blower symptom AND had the updated resistor pack?
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'07 Lotus Exige S - Chili Red

Last edited by JGalt; 11-19-2017 at 09:11 AM. Reason: Corrected spelling
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post #2 of 17 (permalink) Old 11-19-2017, 03:00 PM
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I can't tell from your pictures, but the big value of the update is not the pack but its relocation . If your pack was mounted down low like the original and does not have good connectors (doesn't look waterproof in the pictures), then it is going to eventually have the same failure.

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post #3 of 17 (permalink) Old 11-19-2017, 06:35 PM
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Quote:
Originally Posted by cyow5 View Post
I can't tell from your pictures, but the big value of the update is not the pack but its relocation . If your pack was mounted down low like the original and does not have good connectors (doesn't look waterproof in the pictures), then it is going to eventually have the same failure.
I 2nd Cyow.

Also, i can't even see your updated pack in your photos...mostly because I have no idea what it looks like. Have you checked for continuity across the points on the resistor pack? And personally speaking, I would just make a new one on your own and call it good. Relocate so it is higher up and easier to get to.

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post #4 of 17 (permalink) Old 11-20-2017, 03:34 AM Thread Starter
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Thanks for the ideas guys. Later this week, I'll diagram the photos, but with certainty, the resistors are not sitting low, not sitting in collected water. My '07 Exige has the factory-updated placement of the resistors.

The updated resistor package sits high in the air box, behind the plastic-coiled wire on the upper-right in the first photo.

I did test continuity of the resistors. All good. I did double (triple?)-check fuses. All good. Blower motor is good.

During Thanksgiving break I will re-connect everything to the car and see if ithe blower motor works off the cockpit HVAC controls. The burnt-looking motor connector is perhaps the culprit. I ordered a water-proof connector to splice in. Not sure why it burned, but it is not a waterproof connector. Perhaps water leaked-in at the exact correct angle.

TWO MORE THOUGHTS:
1. I believe my car came from the factory with the updated resistor pack. My car is an '07 Exige. I thought the updated-resistor pack was only '08 MY onwards...but have subsequently found one UK-parts supplier that noted some '07's came with the updated-resistors.
2. My car does NOT have the four holes drilled to drain the water.

Stay tuned. I wish I simply had the poorly-located resistor pack.

Oh, my HVAC control panel has no lights. I'll be ordering a new one. I don't suspect a board failure to have caused the blower's outage...but will have chance to find out.

'07 Lotus Exige S - Chili Red

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post #5 of 17 (permalink) Old 11-20-2017, 03:41 AM
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The four holes are just a band-aid fix to avoid relocating the resistor pack. A relocated pack won't need the holes since water already does drain out of there, just not well.

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post #6 of 17 (permalink) Old 11-20-2017, 05:04 AM
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My Exige is an 07, but built in 06. Perhaps your car is an 07, 07. There are a bunch of changes, bumperettes, maybe AC thermostat, and perhaps resistor pack. Or it could have been updated previously.

I would suggest mounting a replacement resistor pack in an accessible location. The nuisance of getting to it if anything dies makes it worth it

Look at the power connector, it is overloaded.

I used a fused relay and tapped power off of the jump start terminals for high speed, fan runs stronger and the high current path is all up on top where it is accessible. The only thing I didn't replace and I hope I don't regret it, is the power leads right to the motor. I saw someone else did this, making new leads right to the internal fan connections and kicked myself for not thinking of that.

In summary, I am suggesting:

replace the updated resistor pack with either real 100 watt resistors from an electronic supply house[not amazon] or 50 watts screwed to a .09"+ alloy plate as a heatsink

replace the wires all the way to the fan with minimum 14 ga wire.

cut that browned connector off and use the highest quality 1/4 connectors you can find.

If you want to get silly read my AC update thread:

https://www.lotustalk.com/forums/f313...rework-348738/
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post #7 of 17 (permalink) Old 11-20-2017, 06:35 AM
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I agree with @cyow5 about the relocation. What I'm trying to figure out is why on earth would they chose the relocation point be in the assembly box? Where it's even harder to access and it has to pinch the wires when it snaps to the fan...

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I'm about to do a DIY write up w/pics of where I'm choosing to relocate my resistor. Hopefully, I'll have it done in the next two weeks or so. Best of luck trying to figure out the issue but I would definitely consider relocating the resistor to make it easier to work on if an issue comes up again.
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post #8 of 17 (permalink) Old 11-20-2017, 10:15 AM
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I'm thinking that the wire and the foam are why he had trouble getting it out. someone was in there already
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post #9 of 17 (permalink) Old 11-21-2017, 03:08 AM Thread Starter
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Exigeus: I am going to do as you propose. Relocate the resistors. Not sure if I will relocate the resistors I currently have, by pulling them out of of the heater core, our if I'll by the $50 original resistor pack and relocate it. 14 AWG wire and waterproof 14 AWG automotive pin connectors already on order.

I just need to find an ideal accessible place to mount the resistors as I read in another thread that an 180 F reading was recorded on one heatsink. I dont want to be melting anything. Relocation placement SUGGESTIONS ARE WELCOMED.

ZakkAttack86: The heat that these resistors produce is mitigated by being placed in the airflow of the heater core box. I imagine this reduces the efficacy of A/C, though it does explain why Lotus buried these resistors in the air box.

Lastly: I agree that my great difficulty (You all had it much easier) in removing my heater core was due to the foam jamming up the C-channel on the heater blower surround. Oh, and I still think my resistors are original...as updated at the factory.

'07 Lotus Exige S - Chili Red
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post #10 of 17 (permalink) Old 11-21-2017, 03:38 AM
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I found in my update that 100 watt resistors do not overheat. I have them mounted to a heatsink, but it is not required. I measured the temps with the fan in free air and it draws much more current than when installed. By the time I realized my error I had already made and wired the whole thing, so I left it. Buying resistors also allows you to play with the values, getting the low speed truly low is nice. Mouser Digikey etc sell a decent selection. Don't buy on Amazon, they are not really 100 watt resistors unless they are ohmite brand

There a couple of places to put them, top of the pedal box, above the passenger footwell, or just on some standoffs with self tappers on the top of the heater box.

Mounting in the airflow is a pretty standard thing, but with such a marginal AC system, it seems wrong to add extra heat.
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post #11 of 17 (permalink) Old 11-21-2017, 03:45 AM
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Quote:
Originally Posted by exigegus View Post

Mounting in the airflow is a pretty standard thing, but with such a marginal AC system, it seems wrong to add extra heat.
At first blush what you're saying makes sense, but I actually side with Dorman or whoever made the setup (it most likely wasn't Lotus). The resistors only have current flowing through in lower speeds, so full speed doesn't actually put any heat in the system. If the operator has a lower speed selected, then that means the AC is sufficient despite the heat from the resistors.

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post #12 of 17 (permalink) Old 11-21-2017, 04:04 AM
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bergman, bergstrom, written on the tags.....I wouldn't trust them to wash my car no less design an AC system.

That's not fair, it is mostly Lotus not installing it with any degree of sympathy

but still, the connections are overloaded, the pain of replacement is too high, I vote external
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post #13 of 17 (permalink) Old 11-23-2017, 01:09 PM Thread Starter
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I've resolved my non-functional heater blower motor which (already) has the factory-updated resistor pack. The problem appeared to be a poor connector to the blower motor. A previous picture shows how the connector is burned.

After I removed the heater core and blower motor, I cleaned them and reconnected them only to find the blower motor was working. So I suspect the connector was the weak link.

I installed a length of 14 AWG wire and waterproof connectors for the lead that runs from the resistors to the blower motor, replacing the burnt connector (pictured).

The labor and quantity of curse words are no less than that required to replaced a faulty resistor pack. I expect others with the factory-updated resistor pack to have same problem as I did. So I recommend addressing the poor connector(s) when one is in their fiddling around.

Thanks to everyone for the ideas and to Exigeus for the linked pictures.

'07 Lotus Exige S - Chili Red
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post #14 of 17 (permalink) Old 11-23-2017, 01:26 PM
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Mine was updated and was located inside the evap box, failed again anways, I relocated under the fuse box for easy replacement if needed.

2007 Exige S with almost every track mod...
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post #15 of 17 (permalink) Old 11-24-2017, 09:17 AM
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Quote:
Originally Posted by kfennell View Post
Mine was updated and was located inside the evap box, failed again anways, I relocated under the fuse box for easy replacement if needed.
Would you mind sharing pics of your placement? I'm currently looking for a new spot haha
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post #16 of 17 (permalink) Old 11-24-2017, 09:33 AM
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Sorry, didn't realize you still needed a pic. Here is a close up and a wide shot right in front of passenger side front windshield.

Its the gold toned items under the wires for the wiper motor.
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2005 Lotus Elise Graphite Grey - Salvaged title started the SSM build!!!
Maverick ML8 - Other daily
2005 VW Passat Station Wagon TDI (harder to find than the lotus?)
2005 Lotus Elise Starlight Black - Sold
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post #17 of 17 (permalink) Old 11-24-2017, 10:41 AM
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Mine is just 2 sided taped to the bottom of the plastic shroud that holds the fuse box.

2007 Exige S with almost every track mod...
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