I have an early Delanair Mk III system on my '88 XJS.

A/C works well and so does heater. Cool air comes out when it supposed to and vice versa. Problem is with the ventilation. Defogger vents are always wide open, and the center air vent seems to operate minimally at best.

I know that the Delanair Mk III uses solenoid controls for these systems. I see the diagram in the Book, but nowhere do I see where exactly these solenoids are.

I do get a strong vacuum from the manifold, and the reservoir and check valve both hold a good vacuum when checked from the engine bay just forward of the firewall.

I'm guessing the defrost solenoid (and possibly the center vent as well) is either a) nonfunctional or b) not getting a signal from the ECU (due to malfunctioning ECU or corrosion on the electrical connections).

But where the heck are these solenoids actually located so I can begin to troubleshoot?

Thanks for the help!

Cheers,

Will

 

Years ago I had a problem where the center vent flap had somehow jammed against the demister flap....or something like that. Something was out-of-phase.

Here's a cut-n-paste from a posting...part of a long thread....from Jag-lovers in 2006. I wish I could remember more of the details. I do remember the the center flap vacuum actuator was barely visible if the center vent (and woodgrain panel) was removed. You'll have to look upwards from below, at the extreme right side of the center vent opening







"The system is now working properly although I am not sure why....which
leaves me with an uneasy feeling.

Following Ron's lead I went to the other vacuum motor. This has a green
supply tube and is identified as a demist flap actuator held closed by
vacuum. I applied vacuum and, voilá, the center dash flap was quite easily
moved with my fingers. OK ! Now we're getting somewhere. Realizing I had a
control problem, contrary to my initial assesment, I reassembled a few
things so as to begin diagnosis again from a different approach

When enough was put back together to test the system I discovered that all
modes and functions ...including the denter dash vent....were fully
operational although I hadn't (knowingly) repaired anything.

I can only assume (dangerous, I know) that somehow the "inhibit" mechanism
had gotten out-of-phase and operating the demister flap *with the center
flap disconnected* had somehow allowed things to fall back to a neutral
position. If I am corect here I must say I have no idea how it could have
happened."




Cheers
DD

 

DD -

Thanks... got it working. The solenoid responsible for sending vacuum to the defrost actuator was non-functional. Definitely saw the action of the inhibitor, as the center would only operate 1/3 until I finally got vacuum to the defrost actuator, then it would open fully. Replaced it with a spare and now it works as advertised, lots of nice cool air from the center vent!

Unfortunately made the rookie mistake of not taking proper pictures prior to disassembly, and things got a bit mixed on reassembly. Not sure which set of wires is supposed to go to which actuator, I connected the green and black to the defrost actuator. System works well, and I can't every see a point where the center vent and defrost actuator would both see vacuum... only affects which gets vacuum first... (and now that I think about it the inhibitor should stop it from working properly if I somehow mixed them up...).

Reassembly took significantly longer, as the vacuum lines kept pulling free and I finally had to remove the radio to get at things from the back end...

Cheers,

- Will

 

Good work, Will....glad it's all sorted.

Climate control repairs can be tricky....from both difficult access and brain-tease aspects :-)

Cheers
DD

 

@Will

I had the same problem. Glad you figured it out. I also "upgraded" the center vents from the original 3 piece, where 70% of the air cannot be redirected and instead condenses on the rear screen to the later 94 and up 2 piece, which allows you to direct all of the cool air either onto yourself or your passenger. I paid $150 for the 2 piece vent second hand, which was a bit pricey, but I think it's worth it

 

Sarc -

I've been thinking about going down that road as well... but can't find a source for that center dash vent.

I think instead I'm going to make a v-shaped plastic deflector to go in the middle of the center vent to push the air to the side 'adjustable' portions...

Cheers,

Will

 

Yep, that'll work well too. I was lucky that the guy I got replacement solenoids from also had the 2 piece centre vent. I think you could make a nice job with some plastic though....

 

PS : This guy in LA has more than 1 late model XJS breaking for spares...... they have the 2 piece center vents......

http://losangeles.craigslist.org/sfv...112100823.html