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Brian Vogel
Experienced User
Username: guyslp

Post Number: 15
Registered: 6-2009
Posted on Sunday, 07 August, 2011 - 10:10 am:   Edit PostDelete PostView Post/Check IP

I have been presented with a potential opportunity to acquire a 1979 Silver Wraith II that is in need of some serious recommissioning work. The car is in beautiful cosmetic shape, and was serviced many times by an authorized Bentley dealer, but has been dying a slow death from lack of use. The last records I can find are from 2006/7.

The car belonged to someone who simply didn't drive it (other than to take it for occasional service calls). I've never understood this sort of behavior, but that's beside the point.

As it stands the thing that most concerns me is that the climate control does not turn on at all. I did not have the opportunity to do any significant diagnostics when I got to look at the car the other day, but could possibly arrange for more time to do so. This could be as simple as a bad/loose fuse, but knowing these cars I doubt it.

Nothing at all comes on when the climate control switch is turned to any position. I would typically suspect something electrical, but if it isn't, then what might I look at next?

I have dealt with other cars that will not do certain climate control related things if the AC compressor is devoid of charge and the clutch does not engage. Since these cars are designed to always run the compressor when the climate control is turned on, I'm wondering if this might be a possible factor.

What's odd is that nothing happens: no fans, no flaps, no nothing.

Any ideas (including screaming "Run, as fast as you can!!"), theories, etc., would be appreciated.

Brian, who remains uncommitted to this car and intrigued at the same time
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Chris Browne
Frequent User
Username: chrisb

Post Number: 51
Registered: 2-2010
Posted on Sunday, 07 August, 2011 - 08:20 pm:   Edit PostDelete PostView Post/Check IP

Hello Brian,
I don't envy you trying to sort that lot out from scratch! Forgive me if you know this but the aircon system will not work until the engine is running and you have oil pressure. There is an inhibit cycle built into the system which means that the fans wil not operate until the inhibit cycle has been completed. I would check fuse 3 in the passenger compartment fuseboard first and then the small fan and compressor fusebox which is on the bulkhead shelf in the engine bay. It sits just above the first handbrake cable pulley and is a small box about 2" x 1" with a black cover fixed with a knurled screw. Whilst you are in that area, I would check the function of the three relays immediately behind the small fuse box. These are, from left to right, the fan and compressor relay, the fan delay relay and the servo isolation relay. If all those are OK, I think you will have to spend some time studying Section C in the workshop manual. The climate control is a hugely complex system and runs into 140 pages of detailed descriptions and has numerous diagnostic charts to follow. I think all you can do is methodically folow the diagnostics procedures until you have been right through the system and keep your fingers crossed that it is something simple and relatively cheap to fix.
Kind regards,
Chris
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Brian Vogel
Experienced User
Username: guyslp

Post Number: 16
Registered: 6-2009
Posted on Sunday, 07 August, 2011 - 11:19 pm:   Edit PostDelete PostView Post/Check IP

Chris,

Thanks for the additional information. I know how hugely complex the system is and am not the best at reading the diagrams. What I was hoping for and you provided some of is the "list of what to check on first."

The car I currently own was a home market car that somehow made it's way to the U.S. and was converted from RHD to LHD along the way. This has added to levels of complexity since certain things have remained where they should be for a RHD car and others have not.

The car I'm looking at was made for export and has all of the extra pollution control system bits which my car has none of. It was interesting to see just how much more piping is running around in that engine bay than there is in mine.

I have yet to see one of these cars where something has not been done to the wiring loom and/or fuseboard. This car was no exception. There is a large brown with white stripe wire in the loom that has been cut and rejoined using a wiring cap. I'm presuming a short. There is also one fuse on the fuseboard where a modern fuse holder on wires has been soldered in to replace the original fuse.

All of these things give me some pause, but I'm also used to seeing them as well.

Thanks again.

Brian