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2002 V8 AC Gremlin - Interior/Exterior/Lights/Glass/Alarms/ICE/HVAC - The Lotus Forums #ForTheOwners Jump to content


2002 V8 AC Gremlin


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Hi Guys;

Got a bit of a gremlin in the Esprit's V8, hoping that its something that the forum has come across before. Symptoms are:

  • AC not working
  • No sound of compressor clutch engaging
  • Gas has been extracted and re-filled
  • Relay in boot has been tested (closes when I give it 12V)
  • Fuses are all ok

Does anyone have a clue what the root cause might be?

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On the A/C Drier there are four wires going to two plugs. The plug with the red and black wire goes to the a/c compressor. Shorting those two wires will engage the compressor regardless of whats in the system. the other two wires are for the cooling fans. If you short the red and black and the compressor comes on the electrical system side of it should be fine. at that point i would go back to checking pressures in the system.

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Just spent a couple of hours troubleshooting the issue, documenting it here for future reference.

  • Mains off: -ve has continuity to chassis
  • Mains on, engine off: 0v between poles of compressor clutch plug
  • Engine on, fan off: 0v  between poles of compressor clutch plug
  • Engine on, fan on AC off: 0v between poles of compressor clutch plug 
  • Engine on, fan on AC on: 0v between poles of compressor clutch plug,  +ve has 0v to chassis

This lead me to believe that the issue was in the (green and black) +ve wire running from the relay box to the compressor clutch.

I've attached a diagram of what I assume the circuit to be laid out like.

  • I then looked for 12V between terminal 87 and the -ve pole but found nothing
  • I did however find continuity between 87 and the +ve pole
  • I then bridged Terminals 30 and 87 and got 12V between the connector's poles
  • Lastly I found continuity between 30 and 85, meaning that the -ve side of the relay trigger is fine
  • I then connected the plug and bridged 30 and 87 and the compressor started right away  

I have already vacuumed the system, checked for leaks, and filled it with the correct amount of gas as per the manual (1.2 or 1.5kg, can't recall right now). This leads me to the WOT switch and High pressure switch (if present). Does anyone know where these are located? 

 

 

Screen Shot 2016-06-21 at 15.51.00-2.png

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On 6/16/2016 at 19:10, Barrykearley said:

Are the flaps vac operated ??

are you sure you have all the switches in the right place ??

I tested using the indicated positions.

IMG_3838.JPG

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  • Gold FFM

Flaps look to be vac operated and there is a switch contact on the air con one. The parts manual isn't brilliantly clear and I'm struggling to see it exactly and what is connected to what.

the switch on the far right - have you tested the switch contact on the back of that ? .

 

Only here once

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3 minutes ago, Barrykearley said:

Flaps look to be vac operated and there is a switch contact on the air con one. The parts manual isn't brilliantly clear and I'm struggling to see it exactly and what is connected to what.

the switch on the far right - have you tested the switch contact on the back of that ? .

 

No I have not, I was thinking of testing that after the low pressure and WOT switches (as access is probably easier to those).

Edited by jansammut
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22 minutes ago, Barrykearley said:

I can't find them in the parts list of manuals ??! Confused.... Possibly just blind or looking in the wrong place.

I found this, it looks like its in front of the RHS wheel arch. 

Screen Shot 2016-06-21 at 10.06.25 PM.png

Edited by jansammut
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  • Gold FFM

That's on top of the receiver dryer under the hood ?? It's not a picture I recognise from the book I've got - it's slightly different

Ahh that's in the s4 manual.....1993 - it's the high low switch. The v8 manual doesn't show that!!

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1 hour ago, Barrykearley said:

I can't find them in the parts list of manuals ??! Confused.... Possibly just blind or looking in the wrong place.

I found this, it looks like its in front of the RHS wheel arch. 

 

39 minutes ago, Barrykearley said:

That's on top of the receiver dryer under the hood ?? It's not a picture I recognise from the book I've got - it's slightly different

Ahh that's in the s4 manual.....1993 - it's the high low switch. The v8 manual doesn't show that!!

You're right, that's the wrong manual. I reckon I've found it now though part # A082P6075F - Trianry Switch, section 18.03. There seems to be a typo, with it being labelled as part 35 rather than 37

Screen Shot 2016-06-21 at 11.13.51 PM.png

Edited by jansammut
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Any idea how I would go about removing the heater control panel? I've looked in the service manual but can't even find a schematic of my 3 knob type control panel. 

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9 minutes ago, tmusc said:

Do you have power at the red/white wire on the a/c drier?

Here is the wiring diagram. There is no WOT switch it is controlled by the ECM

793.pdf

I have not checked that, does power there indicate that the switch is powering on correctly? Whereabouts is it located?

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it is in the front hood on the a/c drier part #19 on the above diagrams. There is s a switch on the top with four wires. red/white and black. Brown and i forget what the other is. make sure the a/c controls are on before you check for power.

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So, I've got continuity between the Red/white and black wires at all times  this seems very wrong  

With the ac on I get 12v between the blue/white and blue/brown wires. 

Should I get to work on the control panel?

 

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1 hour ago, tmusc said:

If you have no power at the red/white wire i would then suspect the problem being at the control panel.

Awesome, thanks for the pointers!

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  • 1 month later...

I've finally made some time to get back on this issue and disassembled the control panel, unfortunately everything seems (to me at least) to be working fine here.

With the fan running, the temp knob all the way on cold and the potentiometer on full power I get 8 - 10v across Yellow/Black (dependant on position) and Brown/Blue. Once I snap the potentiometer to the off position, I lose voltage across Yellow/Black, but it maintains voltage across Brown/Blue.

Is there a temp. sensor in the cabin that might be at fault here and causing the AC not to trigger? If not I'm totally Stumped.

IMG_4424.JPG

IMG_4425.JPG

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  • 2 weeks later...
On ‎21‎/‎06‎/‎2016 at 20:14, jansammut said:

I tested using the indicated positions.

IMG_3838.JPG

It's difficult to tell from your dials where they are pointing to. The dial to the far right should be positioned fully clockwise at 5 O'clock.

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  • 2 weeks later...
On 8/10/2016 at 20:17, superdavelotus said:

It's difficult to tell from your dials where they are pointing to. The dial to the far right should be positioned fully clockwise at 5 O'clock.

Yes, thats exactly how I tested it. I'm starting to think the the issue is a false WOT signal from the ECU, however electrics are probably my weakest point in car DIY, so I reckon I'll hand it over to someone who knows what they're doing to sort out (as they'll be able to trace and fix much more efficiently than I can).

 

 

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