free hit
Heater Vacuum Soleniod Valve Location - Interior/Exterior/Lights/Glass/Alarms/ICE/HVAC - The Lotus Forums - Official Lotus Community Partner Jump to content


Heater Vacuum Soleniod Valve Location

Recommended Posts

I am trying to help a guy out with his V8 heater.  His current primary problem is the mode flap does not work.  The mode flap is the one that is moved by a vacuum actuator when the dash distribution control is placed in the air conditioning position, essentially shutting off the heated air and opening the two centre stack vents to cooled air.  In the attached diagram from the Parts Manual Sheet 18.11 it is the flap shown upper left.  We can see the vacuum actuator item 9 and the thin vacuum tubes, but not the electric valve that provides vacuum control.  

The part we are trying to locate in the car is Number 18, Lotus P/N Number A082M6666F, Solenoid Valve, actuator control, mode flap.  Not sure if it is behind the centre stack, under the tunnel?  Any help locating this rascal appreciated.  Bonus marks for a description of what we have to dismantle to get at it and check the vacuum lines & wiring is connected correctly. :-)  

Note this component is the same Lotus P/N as Number 45, Lotus P/N Number A082M6666F, Solenoid Valve, actuator control, fresh air re-circ flap.  This one is located in the foot well (as shown in the attached pic) and controls the flap located in the front boot.  Same item but different function.



Heater vacuum controls.jpg

Recirc solenoid valve location.jpg

Heater Box 3.jpg

Stu Calgary Alberta ' 69 Plus 2 '0 0 Esprit V8

Link to comment
Share on other sites

Upgrade today to remove Google ads and support TLF.
  • Replies 3
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted Images

OK, did some more digging.

I found the attached pictures on some of the restoration blogs and the Esprit Build picture file. 

I think the silver box in the first picture is a controller for the airbags (judging by the yellow connectors and harness). I think this view is taken from the drivers side looking forward of the gear shift opening? The brown fibreglass looks like the top of the tunnel?

The plastic tee with the over-sized rubber elbows are in front. Hard to see the valve, but I believe it is behind the yellow wrapped harness, and there is a rubber elbow coming out the top like in the parts illustration. The wires to the electrical plug are White / Orange and Blue / White, which correspond to the wiring diagram for the 'Distribution Solenoid'. 

The second and third pictures show what I think is the same box tucked under the heater box at the base of the centre stack. This view is from the passenger side door.

The fourth picture shows the tunnel partially assembled. I expect the blue lines are the vacuum lines. They may be black in stock form; I think I have seen them running in the engine bay from the top of the left tank over top of the engine.

So, does that look right to you guys?  Any clues on how to take apart the lower part of the centre stack?


Tunnel Area 1.jpg

Dash Out 3.jpg

Dash Out 4.jpg

Dash Out 10.jpg

Stu Calgary Alberta ' 69 Plus 2 '0 0 Esprit V8

Link to comment
Share on other sites

For future reference, I have drawn together a bunch of V8 heater system information and pictures here...

Thanks to all who contacted me with info.  Also particular thanks to all the folks who posted information on the heater system in the various older threads.  the system is confusing because it is covered in so many sections of the service manual and parts book.

Hope the summary information is helpful.


Stu Calgary Alberta ' 69 Plus 2 '0 0 Esprit V8

Link to comment
Share on other sites

  • 2 years later...

This and the LotusTalk thread were very helpful in resolving my 2001MY V8 HVAC issues.

Here's the thing, though. The Diavia stepper motor absolutely has four positions. Remove the arm and use the air direction switch and it will cycle from each side, stopping at two positions in the middle. However, the only thing that matters is that it can find a middle position to direct the air UP AND DOWN at the same time. It can jam against the end stop and direct air upwards, and jam itself at the other end stop to direct air down, and at position 2 where it would also be directed down only-but in position 2-it doesn't matter because the air gets directed through the centre vents using the vacuum servo anyway. The four positions are unusable. I did think about cutting off the end stops to see what would happen, but thought better of it. All Lotus did was use it to have a middle position, and let the end stops take care of the rest.

The whole HVAC system consists of a valve to allow recirculation, a valve to direct air JUST to the centre vents (blue arrow position only) and the stepper motor to direct air up, down, or both at the same time.

This is how you do it.

Start engine. Remove the arm from the stepper, start at position 1 (all to footwell). Wait for stepper to reach end of its travel. 

Move to position 2 (blue arrow). wait for stepper to stop (if it continues to cycle you just have to wait for it to eventually stop, or get a replacement unit-which you can't. Sorry,. Maybe you can remove it and clean or replace the variable resistor?).

Move to position 3 (UP AND DOWN). Wait for stepper to settle. Switch off engine.

Now fit the arm centrally between the stops as best you can. Just as long as it is not touching either end stop and at least some air will go up, and some will go down. The hoses Lotus used are different sizes, and the air paths are different too, so there's very little likelihood of getting an equal volume of air in both directions, so I'm going to just live with that!.  Use whatever you have to stop it moving. My jubilee type hose clip seems to be working so far. Reconnect the metal rod, and use the plastic thing to hold it in place.

That's it, you're done. The switch will now cycle as follows.

Position 4, screen demist.

Position 3, up and down.

position 2, down only (but at this point all the air is directed out of the centre vents anyway.)

Position 1, down only (and the air is no longer directed out of the centre vents).

Its a terrible design, to use end stops to jam the motor, with one jammed end stop stopping the motor from moving at three positions, but that's what we are working with!

All the while, the side vents let air out, and whatever other nuances that Lotus designed in to the box happen too, but this will sort out what the stepper is meant to do.


Edited by LotuStuart
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...