Where is the true weak point of the Lotus A/C system - LotusTalk - The Lotus Cars Community
 
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post #1 of 20 (permalink) Old 12-14-2014, 06:32 AM Thread Starter
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Where is the true weak point of the Lotus A/C system

Hey everyone

I did some extensive reading of the threads about the A/C system and the ways to improve it. My question is, and sorry of it has been discussed before, where is the true weak link in the system. I am in Florida, and although i did all the recommended improvements (and the A/C is actually pretty decent now) I would like to try to make it perfect. Sorry if it has been discussed in the past, but nothing came up in my search. I would like to truly improve the system. the amount of airflow into the cabin is fine, it's the actual temperature in stop and go traffic. Any thoughts? I will test improving various parts. Maybe adding a better condenser fan? Any ideas will help my expedition here. My aim is not to "improve" but to correct the design flaw

Thanks
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post #2 of 20 (permalink) Old 12-14-2014, 07:01 AM
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Originally Posted by MolsbM3 View Post
Hey everyone

I did some extensive reading of the threads about the A/C system and the ways to improve it. My question is, and sorry of it has been discussed before, where is the true weak link in the system. I am in Florida, and although i did all the recommended improvements (and the A/C is actually pretty decent now) I would like to try to make it perfect. Sorry if it has been discussed in the past, but nothing came up in my search. I would like to truly improve the system. the amount of airflow into the cabin is fine, it's the actual temperature in stop and go traffic. Any thoughts? I will test improving various parts. Maybe adding a better condenser fan? Any ideas will help my expedition here. My aim is not to "improve" but to correct the design flaw

Thanks



In the end, you'll hit a roadblock where Lotus intentionally designed the system to be "eh". Even the manual says it is not specced for hot climates, and they did some changes for the Arab market. I don't know what exactly those changes were though right off the top of my head. Instead of being ice cold in the summer, they chose to make it lighter and more compact, so that's probably going to be your bottleneck


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post #3 of 20 (permalink) Old 12-14-2014, 07:09 AM
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- it is a small AC compressor
- the airflow over the condenser is not much
- the evaporator is very small
- the HVAC box is flimsy plastic with no insulation and many leaks
- the recirc flapper is a joke, so hot outside air always comes in
- the interior air return is inadequate
- hot coolant always flows through the heater core
- the foam on the flapper to stop the hot air disintegrates
- the interior fan doesn't provide much flow over the evaporator

I think that's just about every part of the system.

I wouldn't go as far to say the system was 'designed' to be compact and light; it was more likely just cobbled together and this is how it turned out.

Stronger cooling fans, the return air mode and the heater valve mod should help you.
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post #4 of 20 (permalink) Old 12-14-2014, 07:30 AM
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I wouldn't go as far to say the system was 'designed' to be compact and light; it was more likely just cobbled together and this is how it turned out.

Tomato, tomAHto.

Cost and availability of parts from suppliers always has some influence on the final design, but the manual actual does say that the system is designed for milder climates.

Some engineer probably called around asking for the cheapest of everything knowing that it would be smaller and lighter than a more expensive part of similar technological design.


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post #5 of 20 (permalink) Old 12-14-2014, 07:44 AM Thread Starter
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Thank you all for your input. I will try to research a way to add better cooling fans. At least it will be a start. I will also report back. Thanks
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post #6 of 20 (permalink) Old 12-14-2014, 10:19 AM
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Tomato, tomAHto.

Cost and availability of parts from suppliers always has some influence on the final design, but the manual actual does say that the system is designed for milder climates.

Some engineer probably called around asking for the cheapest of everything knowing that it would be smaller and lighter than a more expensive part of similar technological design.
Such generosity!

Some engineer probably called around asking for the cheapest of everything knowing that it would be ... the cheapest of everything.

The manual isn't going to say, we compromised on the climate control because we couldn't afford to put in the engineering effort it would take to do a proper system.
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post #7 of 20 (permalink) Old 12-14-2014, 10:32 AM
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I heard of people switching to R152a and it helps. I believe some people on youthbe got the air coming out at 30f which is colder than most fridge.
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post #8 of 20 (permalink) Old 12-14-2014, 11:42 AM
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...and they did some changes for the Arab market. I don't know what exactly those changes were though right off the top of my head.
My understanding is they added a second, electric a/c between the seats. That was according to someone who posted on here once with a GS (I think it was called GS) edition.
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post #9 of 20 (permalink) Old 12-14-2014, 07:00 PM
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I'm forgetting the problem with temperature probe in the evaporator too. Search for all these problems and you'll find a lot of advice.
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post #10 of 20 (permalink) Old 12-14-2014, 09:35 PM
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The way Lotus improved the AC system for Gulf (GCC) markets was :
1) Reduce solar loading : windscreen is different, with solar layer
2) Reduce heat soak : interior is fully insulated, no bare chassis tub or alloy gear/handbrake trim
3) Additional evaporator / blower unit behind the seats. the small front evaporator (and its potential for icing) is the main reason you'll never get a standard system 'cold'.

These combined will get the car fully cooled, even in 45C heat left heat soaked without shade. Go to an on-line parts manual & look at 'Gulf States' parts built into Elise / Exiges from MY 2009. Its all documented.

HTH
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post #11 of 20 (permalink) Old 12-15-2014, 07:07 AM
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want to know what the OP comes up with...need to pull my system out soon so if there is a way to improve it, I plan to.
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post #12 of 20 (permalink) Old 11-09-2015, 08:31 AM
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I am going to either get rid of the car....or do anything I can to get the AC to decent cooling standards.

So are the any updates to this thread findings?
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post #13 of 20 (permalink) Old 11-09-2015, 08:53 AM
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So at one time I found the EXACT A/C system used in the Lotuses shipped to Saudi Arabia/Eastern countries (from the U.S.). Their cooling capacities were AMAZING and worked really well. Summitracing used to sell the exact unit for about $500, and it mounted in the back of the vehicle where the cabin light is located. However, I can't find that A/C unit anymore. I did however find another company that made something similar, and with a little bit of pipe work, could work really well in our cars as well.

Black Dual Vane Underdash Air Conditioning System - Restomod Air

I will see if I can find the Original AC unit again.
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post #14 of 20 (permalink) Old 11-09-2015, 09:04 PM
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So we can simply fit an additional evaporator/blower unit in the car to tap onto the existing condenser & compressor? Wouldnt this like overload the compressor or condenser or something?

Space constraints aside, how easy/difficult is it to pipe/connect to such a unit? I imagine either under dash or custom a backboard behind the seats.
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post #15 of 20 (permalink) Old 11-09-2015, 11:49 PM
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https://www.lotustalk.com/forums/f313...rience-286105/ The Gulf States cars tapped into the existing condenser and compressor, so it worked for someone...

I agree with others on the thread that you should look into some of the other mods first. Blocking off the heater core, outside air intakes, and checking on the AC evap thermostat like in this thread: https://www.lotustalk.com/forums/f313...install-91048/ .

Aftermarket / Gulf AC is appealing because it could solve all of the issues with one stone by bypassing the bad OEM HVAC box, fan, intakes, and evaporator all at once, but plumbing it would probably be very hard at best. I don't know of anyone who has successfully installed one.
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post #16 of 20 (permalink) Old 11-10-2015, 05:24 AM
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Yeah, did all I can according to the improving AC thread. I am now thinking of swopping to an upgraded radiator and a fresh new condenser with stronger fans just to see if it helps.

And while the clam is off, I am going to insulate the entire wall separating the rads from the evaporator housing proper. Perhaps custom an extensive heatshield and hope the heatsoak issues can be resolved. I have totally and permanently bypassed the heater matrix and pipings.... So I guess the only source of hot air is either from the rads upfront or leakage of ambient air somewhere into the air distribution chamber.

Yeah mine blows warm air even
when AC is turned off while driving after a few minutes.
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post #17 of 20 (permalink) Old 05-12-2019, 06:28 AM
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The only thing wrong with the A/C is the lack of airflow over the condenser in urban driving. I'm sure all of you had adequate cooling once the car is on the move.

I've tried to research for higher cfm fan for the radiators but found that the ones that came with the car are already the highest flowing fans that could fit within that space, the only way to solve this is to add a 2nd condenser and sandwich it in between the radiator and condenser. Not the most ideal solution as it is very near the radiator plus the incoming airflow for 2nd condenser is above ambient temp. but this is the best way to do it coz the right rear arch of the car doesn't have much space for a 2nd condenser either.

Add 2 more top mounted pull fans to reduce the pressure under the radiator, it will help increase overall airflow too.
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post #18 of 20 (permalink) Old 05-12-2019, 07:46 AM
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You could be correct, but interestingly they do not seem to change the condenser with the Gulf AC upgrade.

IF you read my thread
https://www.lotustalk.com/forums/f31...rework-348738/

You will see that the stock condenser is upside down[just a little bit, but hey, we need every bit we can get]

After an ECU flash, my fan seems to be coming on high at a lower temperature, so I will be interested to see if forcing the fan on high will help with stop and go traffic.

at this point I am unsure if the poor traffic performance is airflow or refrigerant flow related
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post #19 of 20 (permalink) Old 05-13-2019, 06:47 PM
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A/C specialists told me that it's impossble to fit a different compressor given the space, i guess the best test for COP improvements will be R152a.

Perhaps we may even need to do both. An easy test will be to idle the car in front of strong fans like those they use for Dyno, if this works, cooling is the key.

Have you found any fans that can flow more air thru the stock condenser? The only way I found was by hooking up 18 units of 92x92mm waterproof casefan from computers. That will boost airflow to 3000cfm, but it will draw 50-60A of current!

My stock fan runs at full speed in traffic, but it doesn't help. Vent temperature is 26 degree C at 34 degree C ambient, cabin temp is 30 degree C.

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Originally Posted by exigegus View Post
You could be correct, but interestingly they do not seem to change the condenser with the Gulf AC upgrade.

IF you read my thread
https://www.lotustalk.com/forums/f31...rework-348738/

You will see that the stock condenser is upside down[just a little bit, but hey, we need every bit we can get]

After an ECU flash, my fan seems to be coming on high at a lower temperature, so I will be interested to see if forcing the fan on high will help with stop and go traffic.

at this point I am unsure if the poor traffic performance is airflow or refrigerant flow related

Last edited by powersteer; 05-13-2019 at 06:53 PM.
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post #20 of 20 (permalink) Old 05-14-2019, 03:21 AM
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with those temps your AC is not working period, it is not about air flow or refrigerant
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