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Discussion Starter · #1 ·
I tried searching for almost an hour on this forum and another as well so either I'm the only one with this possible problem or my searching abilities are pitiful.

2013 Evora IPS NA

Couple of points
- at times, not always, there seems to be a cold draft in the footwell - why?

- when using the heat, it seems that I can't get the air to come out of two vents at one time. For example, the footwell and the dashboard although the knob obviously lets you turn it to a position where you could do that. I can definitely switch between vents but can't seem to have it come out of both vents at the same time.

Maybe there is an issue with the vents opening and closing properly but thought I would put it out there before I raise it with the dealer at my next service appt.
 

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Keep it on recirc or follow the instructions linked by tbd
 

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Discussion Starter · #4 ·
Thanks! amazing that I couldn't find that in the forums. When I bring it in for service next month, this will definitely be on their to do list. Appreciate the help and glad to hear its not just me
 

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Illegal Alien
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I have seen a few other threads here on this subject too.

One thing I would Strongly recommend not doing on a self fix, is to use balsa wood for the block-off panel. A highly flammable material in a location hidden behind a wiring panel and exposed to an air supply - ignition - fuel -and oxygen great combination. Better a sheet of aluminum, CF or ABS plastic as min.

Additionally isn’t this a band-aid fix without getting to the cause of the problem? Doesn’t closing this off except for a few tiny holes reduce the effectiveness of recir ... maybe not a problem in Europe where BMW owner’s manuals warn to not leave car on recir too long as cabin air quality will diminish.. ha, they do not drive in LA or Houston much nor in hot weather, where an A/C will not compete with cooling 100% outside air.
 

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Illegal Alien
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Decided to look into the parts and service manuals to see what should be going on vs. what may be going on:

"Re-circulation SwitchThis switch functions with the key at the accessory or ignition positions, and will maintain its status throughout ignition cycles. The re-circulation port in the footwell toe-board is open at all times, such that the greater proportion of air drawn into the fan chamber, via a duct incorporated into the bottom of the HVAC housing, is always from the cabin interior. The fresh air intake on the top of the unit is controlled by a stepper motor and flap valve, and is normally open to provide approximately 30% fresh airflow. To close the intake and prevent fumes being drawn into the cabin, or to provide the quickest response to temperature change requests, the fresh air intake may be closed off by pressing the re-circ. switch, to result in 100% re-circulation. This option should, however, be used sparingly to avoid stuffiness in the cockpit."
 

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Illegal Alien
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"Ambient air collected from the top of the intake duct, ahead of the engine radiator, is fed via an insulated fibreform duct to a pollen filter mounted at the intake to the HVAC unit, within which the airflow is divided towards the inner and outer sides of the two blower fans. Air enters the fan drums axially and is centrifuged outwards to be directed into the evaporator chamber.

A second intake duct collects air from the cabin interior via a central aperture in the footwell toeboard, from which the air flows through a duct formed in the lower section of the HVAC unit and into the fan chamber in a similar manner to the ambient flow.

Electrical resistors used in the fan speed circuitry are cooled by the incoming airflow stream.

The fresh air intake may be closed off at the driver's request by an electrically operated flap at the top of the unit, which closes or fully opens the ambient air intake.

The re-circulation intake is open at all times.

All air exiting the fan chamber is directed through the evaporator, whether or not a.c. is selected, and is then divided between routes flowing either past, or through the heater matrix by an electrically operated air blender flap, the position of which is determined by the temperature selector knob. Blended air then leaves the top rear of the HVAC unit and enters the Air Distribution Unit (ADU) which passes beneath the base of the windscreen and is secured to the top of the footwells. ..."


From reviewing the service air distribution diagram, it seems as if outside air is leaking out of the blower fan into the cabin recir intake .. pushing recirc closes the outside intake, however with recir off both intakes are open to the squirrel cage fan. Output of the fan is through the A/C condenser then either out vents or through cabin heater .. path of least flow restriction may be out recirc inlet vent rather than through two sets of coil units.

Good news of the "fix" is that heated air is not directed out behind the electrical panel; however a real fix would be a flapper gate on this recir intake that partially closed when outside air was selected. The fix of a panel with a few holes will defiantly mess up the efficiency of a recir system and for us Texas, Arizona, Nevada folks we may on survive the +105 temps.
 

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I also read the description in the repair manual and had to chuckle. Obviously the engineer who designed it didn't take wind pressure while driving into consideration. At speed cold outside air is pushed backward through the supposed recirc ais intake.

I actually did make a flapp type solution, but it will always be a compromise. So, if your bigger problem is hot weather then don't make the mod, bit if you're in a colder climate and frequently run at higher speeds the mod is a must.
 

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Illegal Alien
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I also read the description in the repair manual and had to chuckle. Obviously the engineer who designed it didn't take wind pressure while driving into consideration. At speed cold outside air is pushed backward through the supposed recirc ais intake....
It’s amazing the breadth of engineering expertise at Lotus; world class chassis designers but a simple HVAC or (DRL) system that has been perfected by industry years ago, and they just can’t get it. May be a symptom of NEH.
 

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Discussion Starter · #10 ·
Just to put some closure on this as I just got my baby back from the dealer and my concerns over the venting have been resolved. While they couldn't find anything specifically blocking the vents or any flaps stuck, they did dig around and also readjusted the steering column a little and I have to tell you that the cold draft from the footwell is completely gone and the venting system works 10x better than before they took it in. The air blows strong from all the vents the way it should.
 

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The Tech/Wiki solution with a blanking plate with only a few small holes will spoil the recirculation and reduce the efficiency of the AC. I made a non-return valve with a thin rubber flap, and made 8 holes each 22 mm, easy to make. No air can enter the cockpit this way, but full recirculation possibility is kept. I can post photos if you don`t follow.
 

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Please do post pictures.
 
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