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-   -   Resistor Pack bypass (https://www.lotustalk.com/forums/f279/resistor-pack-bypass-116607/)

yellowvert 06-10-2012 07:45 PM

Resistor Pack bypass
 
From the idea BlackSix posted and with lots of help, calls and coaching from SirLotus, I successfully bypassed the dead resistor pack today. THe entire process took me about 4 hours. I believe a well prepared person with a ready helper (who is ideally about 4'2" with small but strong hands) could accomplish what I've done in a couple of hours. I'll walk through the thought process and the procedure. I took a few pictures but because of the location, they aren't great. They should help with context at least.

If you frequent this section of the forum, you understand that tragic design of the HVAC Fan Resistor Pack. Putting the resistor at the bottom in a sealed pan just doesn't even remotely make sense but we didn't buy these cars for practicality. I called the local dealership. I was quoted $495 for a new fan and resistor pack and was told that's the way its done....replace them both. Total estimate to pull the clam, clear the freon, remove the A/C, replace the freon and reinstall every thing was $1800. And, oh yeah, the parts won't be in the US until mid-July! I live in Dallas. With my daughter home for the summer, the Lotus is a daily driver.

I then went to a local Lotus service guy. He was really helpful but just said "you can do it....it won't be hard". While I think I could, I was kind of dreading pulling the clam as I'd be doing it alone. The fear of scratching the car or having one dang bolt left over was tough.

SirLotus and others can explain this better but the idea posed was whether one could access the proper wires through the footwell firewall, splice in, route the wires and connect them to the switch. SirLotus wasn't aware that anyone had tried this. I was an easy mark.

What we are trying to accomplish is to bypass the resistors. I'll be cutting the orange power wire that ran to the motor and connecting it directly to the #3 position on the rotary knob. This means I'll have either off or full blast on. If you own one of these cars and if you live anywhere that actually requires AC, you know that we really only have 2 positions - off or full speed.

(This does bring up the ethical issue of not keeping the car stock. And I'm clearly making the car "less functional". I rationalized this in many ways. 1) I don't want to spend $1800 for what should be a $300 job 2) I'm a little leery of pulling the clam 3) I just know as soon as I spent $1800, I would immediately get hit or be in an accident which will require someone's insurance company to pay for removing the clam. And when that happens, I'll replace the motor and pack and go back to bone stock. If this is sacrilegious to you, read no further.)

Here's the view of footwell to start:

http://i220.photobucket.com/albums/d...e/IMG_3632.jpg

Step 1: Remove the Driver's side seat. You need all the space you can get. There are 2 13mm bolts at the front of the rails and 2 6MM hex head (allen head) bolts at the rear. There is a 17mm (use open end wrench) bolt which holds the seat belt to the seat. Once all free, carefully remove the seat. Its easy to scratch stuff with the sharp rail ends. I forgot about the "fasten seat belt" wires but they conveniently just pulled apart. If you want to be more careful, once the seat rails are free, rock the seat forward and reach under. But cover the front of the rails so they don't scratch the extruded cross-wire aluminum (that the rail bolts into).

http://i220.photobucket.com/albums/d...e/IMG_3633.jpg

Step 2: with a Sharpie, trace around the plate which covers the vent holes. You need to know where to cut.

http://i220.photobucket.com/albums/d...e/IMG_3634.jpg

Step 3: Remove the plate covering the 5/16" perforations. Select a drill bit slight larger than the hole in the rivet and drill them out, I used one that measure at .187" and it worked fine. Drill out all 4 rivets and remove the plate.

Step 4: Make an access port by cutting on the traced line. I used a Dremel tool with metal cutting wheels. Note: I initially didn't have the 90 degree adapter for my Dremel. Because the Dremel is relatively long, it was difficult to work. I went through the 6 cutting wheels I had quickly. Home Depot didn't stock this adapter but Lowe's did. It was $30 plus I bought another 10 cutting wheels (~$10 for 5).

http://i220.photobucket.com/albums/d...e/IMG_3635.jpg

Once I had the adapter, the quality of my cutting improved dramatically.

A couple of points to be made here.

1) Initially, I was thinking I would cut this neatly and when done, just silicone glue it back into place. As you can see below, what I did was simply not clean enough to do that. I'll be looking for someone to fabricate a new plate with perforations that'll I attach over this hole to clean up the appearance.

http://i220.photobucket.com/albums/d...e/IMG_3636.jpg

2) IMPORTANT: We knew there was some level of structural bracing running through the area but not sure where. It turns out that if you cut more than about 1/8 below the bottom line, you'll start cutting this bracing. I believe if you didn't know better, you could do this. If you start with a side or top, you'd know what cutting through one layer is like versus cutting the structure. Not only is it harder to do, you really don't want to do that! (Note I did nick mine but it won't be a problem. - see the red adhesive on the picture.)

3) Because I wasn't exactly sure what was behind this, I went through some level of pains to tape from the back and front of the perforated plate I was cutting so it couldn't fall in. I suppose it could and be a little challenging to remove, I'd say this is optional.

4) Once you remove the plate, immediately tape up the exposed edges with painters or duct tape. Otherwise, you WILL cut yourself.

Step 5: You can see the fan! You also can see that the fan is recessed about 5 inches, making it harder. The bent panel in the footwell on the passenger side partially covers perforations like the previously completely sealed perforated panel on the drivers side. These are both "cold air returns" or how the cold air in the cabin is recycled or recirculated. The air that comes in from the passenger side flows toward the drivers side in the chamber that the fan motor is attached. Hence the reason for depth.

Hopefully, you can see a couple of wires one each orange and black. The circle around the motor itself before taking a radius out. On my car, the orange wire started at about 9:00 and the black started at about 12:00. They circled counter clockwise behind the structure veins of the fan (closer to you then the squirrel cage itself) and go down at about 5:00. If you look closely, you can just make out a small wire tie on this vein.

http://i220.photobucket.com/albums/d...e/IMG_3638.jpg

Your goal now is to get as much slack as possible in the orange line. Remove the wire tie. Try to separate the orange and black as much as possible. You do NOT want to cut the black (ground) line. It stays.

http://i220.photobucket.com/albums/d...e/IMG_3642.jpg

With your wire cutters, reach down and far as you can - even into the foam seal - and cut the orange wire. And now would be a good time to pray that the resistors are actually what your problem is.

Push-feed the wire back under the veins at 5:00, 7:00 and 8:00 and then pull the orange towards you. If yours is like mine, the wire comes within about 1" from actually being accessible. Mine did not leave the cavity.

Step 6: Find your favorite little person now. I somehow got my wife to help (pathetic look on my face). She wasn't real pleased about being in a confined space with sweaty me from 4 hours in the garage at 95 degrees.

I bought a 12 foot section of 12 gauge AWG wire from Autozone and some 12 gauge butt connectors. Put a butt connector on the 12 gauge wire. Then, while holding the orange wire steady, insert the 12 gauge with butt connector through the opening, simply slide it on the orange wire and just crimp it in place! This step took me about 45 minutes to realize it was simply impossible to do by yourself. Not only did I need her help but she also had the good idea (after about 20 minutes) to grab a couple of hemostats to add in holding.

It worked! Candidly, the orange wire had about 1/8 inch wire exposed beyond the butt connector. I don't know if I had too much striped or not but the connection withstood a reasonable tug. I smeared the exposed part with RTV and encased the whole thing with shrink wrap.

Happened that Michael (SirLotus) called to check on me at that time. He immediately suggested that I just jumper it to the positive terminal on the battery. We then virtually celebrated as the fan turned on.

Step 7: Courtesy of Michael's knowledge, I then pulled the HVAC control panel out and pulled the plugs off the terminals for the the green/gray and green/blue. These control positions 1 and 2. I don't think it would matter but I pulled them because Michael told me to!.

http://i220.photobucket.com/albums/d...e/IMG_3643.jpg

I then unwrapped a little piece of tape holding these wires so I could cut the green/yellow (#3 or full speed) wire. I choose to insert a male/female plug there.

http://i220.photobucket.com/albums/d...e/IMG_3644.jpg

Check it all - still works - and I'm done for the time being.

2 problems remain:

1) I have to do something about the hole in the fire wall. I know what I want - does anyone have access to a machine that could cut a word or design into a piece of 1/8 aluminum?

2) I've got to figure out how to run a wire into that HVAC controller area. Right now, I just have the 12' of wire balled up and sitting on the parcel shelf. I'll be posting to look for help on that next.


Thanks to BlackSix for proposing the idea and serious thanks to SirLotus for talking me through this (talking me into this!). I can assure you that he spent more time working on this than I did. This is when the forum really works - good people willing to help. I hope this write-up helps someone else. I'll review and edit later.

Scott

Glen 06-10-2012 11:12 PM

Interesting repair. I'm afraid I couldn't bring myself to cut the sheet metal in that area, even if it is perforated. I wouldn't want someone else to see what I'd done :( ... but that's not my point ... here are a couple of ideas about the tools you used.

When drilling out pop rivets, use the same size drill as was used to install the rivet. In your case - those look like 1/8" rivets - I would have just drilled the heads off with an 1/8" drill. Stop as soon as the head spins off on your drill - there's no need to drill any farther. The pop rivet body can usually be pushed out the back with an awl or a pin punch (or if you have access, pulled off with pliers). This leaves a correctly sized hole for the same rivet size when you replace it.


Abrasive parting discs are my last resort for cutting thin sheet metal - they are a dicey proposition at best. A much easier tool for cutting sheet metal in your situation would be a nibbler. It goes into a hole or starts at an edge and takes a small square or rectangular bite out of the sheet metal without distorting either side of the cut. Take successive bites to cut along a line. This tool comes in both pneumatic/electric or hand-powered versions (I'd stay away from the drill motor attachments though). The hand-powered version would work fine (albeit a little slow) for your application. It's a very handy tool - especially for blind cuts in the middle of a panel like yours.

Glen

jlotusd 06-11-2012 01:47 AM

3 Attachment(s)
it seems like you can still use the number 1 and number 2 fan speed by using this diagram. using your tap wire from the motor, use in-line splice ( which is black wire 12 gauge you used, orange/red wire on the diagram ) red wire for number 2 and yellow for number 1 at slow speed. but you have to cut the existing wire which is green/gray and green/blue like you did on green/yellow. pictures are from rob13572468.

SirLotus 06-11-2012 03:08 AM

Quote:

Originally Posted by jlotusd (Post 1747383)
it seems like you can still use the number 1 and number 2 fan speed by using this diagram. using your tap wire from the motor, use in-line splice ( which is black wire 12 gauge you used, orange/red wire on the diagram ) red wire for number 2 and yellow for number 1 at slow speed. but you have to cut the existing wire which is green/gray and green/blue like you did on green/yellow. pictures are from rob13572468.

Firstly, I want to applaud "Yellowvert" for attempting this repair and also taking the time to post his experiences.
Actually the location of the resistors is important. Due to the heat they generate, they have to be placed in constant moving airflow. This is the reason for the factory location. Another alternative is to install a solid state electronic variable speed 30A DC motor controller Motor speed controller. This unit can be installed anywhere as it does not generate high temperatures like the resistors.
Michael

yellowvert 06-11-2012 05:00 AM

Quote:

Originally Posted by Glen (Post 1747356)
Interesting repair. I'm afraid I couldn't bring myself to cut the sheet metal in that area, even if it is perforated. I wouldn't want someone else to see what I'd done :( ... but that's not my point ... here are a couple of ideas about the tools you used.

When drilling out pop rivets, use the same size drill as was used to install the rivet. In your case - those look like 1/8" rivets - I would have just drilled the heads off with an 1/8" drill. Stop as soon as the head spins off on your drill - there's no need to drill any farther. The pop rivet body can usually be pushed out the back with an awl or a pin punch (or if you have access, pulled off with pliers). This leaves a correctly sized hole for the same rivet size when you replace it.

--I'm sure your right on this. Since I didn't care about quality, I just tried a couple until the head popped on the drill bit. It'll get covered at some point.

Abrasive parting discs are my last resort for cutting thin sheet metal - they are a dicey proposition at best. A much easier tool for cutting sheet metal in your situation would be a nibbler. It goes into a hole or starts at an edge and takes a small square or rectangular bite out of the sheet metal without distorting either side of the cut. Take successive bites to cut along a line. This tool comes in both pneumatic/electric or hand-powered versions (I'd stay away from the drill motor attachments though). The hand-powered version would work fine (albeit a little slow) for your application. It's a very handy tool - especially for blind cuts in the middle of a panel like yours.

Glen

-- I wasn't real happy about this either. Lots of nasty dust, fear of the disk flying apart, etc. I'm not aware of this tool but will look into it for future use.

rcuser 06-11-2012 06:43 PM

Thank you yellowvert for trying this and it being succesful and blacksix for the idea and sirLotus for help. Then also documenting and sharing with us.

On pic 1 there's the solid alum panel thats held by the 4 rivets.
If one was to cut the opening smaller; an area within the 4 rivets just along the perforated air holes in pic 3, then maybe the solid alum panel can just be riveted back in place, or use some type of screw/bolt for easier access in the future? Then discard the piece with ventilated holes? Is this possible, and any harm in discarding the cut out piece with perforactions

SirLotus 06-11-2012 07:04 PM

Quote:

Originally Posted by rcuser (Post 1747734)
Thank you yellowvert for trying this and it being succesful and blacksix for the idea and sirLotus for help. Then also documenting and sharing with us.

On pic 1 there's the solid alum panel thats held by the 4 rivets.
If one was to cut the opening smaller; an area within the 4 rivets just along the perforated air holes in pic 3, then maybe the solid alum panel can just be riveted back in place, or use some type of screw/bolt for easier access in the future? Then discard the piece with ventilated holes? Is this possible, and any harm in discarding the cut out piece with perforactions

It is advantageous to remove both footwell solid panels to improve the HVAC performance by increasing the airflow. https://www.lotustalk.com/forums/f313...-system-71031/
Michael

rcuser 06-12-2012 06:53 AM

^^I see now

I wonder if one can access the orange wire going to the resistor and have enough slack/access to crimp it to the main red wire going to the blower. It's tight down there and not sure if a hand could even get to the resistor pack via feel.

This would avoid routing a 12awg wire to the HVAC control knobs, right?

SirLotus 06-12-2012 06:59 AM

Quote:

Originally Posted by rcuser (Post 1747884)
^^I see now

I wonder if one can access the orange wire going to the resistor and have enough slack/access to crimp it to the main red wire going to the blower. It's tight down there and not sure if a hand could even get to the resistor pack via feel.

This would avoid routing a 12awg wire to the HVAC control knobs, right?

We had considered this, but came to the conclusion, that it was next to impossible.
Michael

407Driver 06-12-2012 09:28 AM

1 Attachment(s)
Thanks for the write up on this, nice to have a proven option to removing the clam. I don't think you need to cut the opening quite that wide to access the red wire. My solution for finishing everything up and having a factory look with increased airflow and maybe keep some of the debris out of the fan area... I used the same plate from the passenger side ordered from lotus garage held with plastic rivets, works great looks good.

SirLotus 06-12-2012 09:49 AM

Quote:

Originally Posted by 407Driver (Post 1747962)
Thanks for the write up on this, nice to have a proven option to removing the clam. I don't think you need to cut the opening quite that wide to access the red wire. My solution for finishing everything up and having a factory look with increased airflow and maybe keep some of the debris out of the fan area... I used the same plate from the passenger side ordered from lotus garage held with plastic rivets, works great looks good.

Even the partial passenger side plate restricts air appreciably. It makes sense to cut all the way around the perforated air return rather than cut across holes, leaving jagged edges.
Michael

rcuser 06-12-2012 10:14 AM

Quote:

Originally Posted by 407Driver (Post 1747962)
Thanks for the write up on this, nice to have a proven option to removing the clam. I don't think you need to cut the opening quite that wide to access the red wire. My solution for finishing everything up and having a factory look with increased airflow and maybe keep some of the debris out of the fan area... I used the same plate from the passenger side ordered from lotus garage held with plastic rivets, works great looks good.

it looks clean, What did you connect the red wire to? how did you route it? thanks

407Driver 06-12-2012 12:11 PM

Quote:

Originally Posted by SirLotus (Post 1747978)
Even the partial passenger side plate restricts air appreciably. It makes sense to cut all the way around the perforated air return rather than cut across holes, leaving jagged edges.
Michael

I experimented with both finishing plates on, both off ..... no discernable increase in air flow, that little fan can only do so much.

yellowvert 06-12-2012 12:40 PM

407: I can't comment on airflow because I didn't attempt to measure it. What I can say is:

1) The value in doing this is to improve recirculation. If you consider that 75% of the overall perforated area (used for recirc air from the drivers compartment) is blocked, this has to help.
2) If you aren't running the AC in recirc mode, then you are still sucking in a lot of hot outside air

3) On my ride home yesterday, it was full sun, 95 degrees, 50% humidity with a THI of 105 (as per WeatherBug locally). Last year, on similar days, I would be warm with a level of sweat on my back by the time I go home. Yesterday, within minutes, I was nearly cold. I stopped, rolled the windows down while I went in the store to bring the temperature back up. Got in the car and again, within minutes, was nearly cold. Keep in mind that I have only full blower speed. What I didn't do was try to see the differential of with and without running recirc mode.

So, my sweaty butt seat of the pants answer is the increased recirc airflow makes a big difference. Your mileage may vary!

yellowvert 06-12-2012 12:48 PM

Quote:

Originally Posted by rcuser (Post 1747734)
Thank you yellowvert for trying this and it being succesful and blacksix for the idea and sirLotus for help. Then also documenting and sharing with us.

On pic 1 there's the solid alum panel thats held by the 4 rivets.
If one was to cut the opening smaller; an area within the 4 rivets just along the perforated air holes in pic 3, then maybe the solid alum panel can just be riveted back in place, or use some type of screw/bolt for easier access in the future? Then discard the piece with ventilated holes? Is this possible, and any harm in discarding the cut out piece with perforactions

You make a good point. Had I cut in enough to allow me to use the same size panel, it probably would have been enough to allow one to re-rivet in the perf panel and then maybe add some small aluminum trim to clean it up. I will tell you that when you are standing on your head trying to get one hand back there (and then add a second little person later on to help crimp), the more space the better. But cutting it 1/2 on each side wouldn't have mattered. I think cutting it 1/2 on top and bottom WOULD have mattered. Again, in retrospect, cutting just a little less off top and bottom might work.

Sorry, thinking as going...if you cut it narrower (less off sides) you could re-rivet. I'd generally stick with all the height possible because you would need to add the trim on all 4 sides. I just don't think its reasonable to think you could cut it so clean and straight that you wouldn't notice. Lord knows I didn't but I realized instantly that that wasn't something I could do. Maybe wrong tool?

SirLotus 06-12-2012 12:55 PM

Quote:

Originally Posted by 407Driver (Post 1748058)
I experimented with both finishing plates on, both off ..... no discernable increase in air flow, that little fan can only do so much.

Airflow meter in the dash vents and proved the airflow was appreciably higher. The fan is not undersized, rather the ducts restrict the flow.
COCKPIT VENT AIRFLOW ................RECIRC. OFF................RECIRC. ON
.................................................. ....(Outside vents open)...........(Outside vents closed)
Footwell vent closed (normal)----------27mV........................16mV
Footwell vent open (modified)----------50mV .......................45mV
There is a greater airflow at the vents with the outside air intakes open, but that air, in the A/C mode, is warm, unconditioned and could result in a higher cockpit vent temperature.Note – Higher voltage (mV) equals greater air flow

Michael

407Driver 06-12-2012 12:57 PM

Quote:

Originally Posted by rcuser (Post 1747990)
it looks clean, What did you connect the red wire to? how did you route it? thanks

Thanks, route the wire from the AC switch panel (requires drilling one hole behind the switch panel) over to the passenger side cubby (remove the cover) and you can see a space where the wire can be fed down and then forward along the underside of the dash and push the wire thru to the front side of the firewall via the main harness grommet. There is room to squeeze the wire between the firewall and the fan housing foam grommet.
Go back in the driver footwell and strip the wire, put the connectors on, install finishing plate.

SirLotus 06-12-2012 05:07 PM

1 Attachment(s)
Another "possible" way of routing the wire(s) to the HVAC console is to remove the radio and route the wire up the back of the dash and through the existing HVAC grommet.
Michael

yellowvert 06-12-2012 06:44 PM

Michael, but the "yeah but" is....how do I get the wire up to the radio from the cockpit? I was so tired (and still sore!) I didn't look too much up there but I reach around and didn't feel any obvious opening. Maybe its through the passenger side cubby?

And one of these days soon, I'll be calling to chat about the solid state controller, etc. I would like to get multiple speeds back. When I do that, the car won't be "original" but it will be "fully functioning" - and arguably better (if nothing else due to your opening of the recirc mod).

Can you explain why Lotus limited recirculation in the first place? I haven't been able to figure that one out.

SirLotus 06-13-2012 04:35 AM

Quote:

Originally Posted by yellowvert (Post 1748248)
Michael, but the "yeah but" is....how do I get the wire up to the radio from the cockpit? I was so tired (and still sore!) I didn't look too much up there but I reach around and didn't feel any obvious opening. Maybe its through the passenger side cubby?

And one of these days soon, I'll be calling to chat about the solid state controller, etc. I would like to get multiple speeds back. When I do that, the car won't be "original" but it will be "fully functioning" - and arguably better (if nothing else due to your opening of the recirc mod).

Can you explain why Lotus limited recirculation in the first place? I haven't been able to figure that one out.

Scott, I Just discovered that there is no access from the radio slot to the wiring grommet that goes to the HVAC console.
There are two reasons why the airflow is restricted;
1) I believe the ducts to each cabin discharge vents are too small.
2) The footwell returns were blocked because on a cool day with the heater/fan off there would be a backflow of cold air through the returns. Apparently owners were complaining and Lotus used this method to address it. The disadvantage is that it also inhibits the airflow in, thereby restricting the flow out of the cabin discharge vents
Michael


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