Hello all...

Fix one thing and new things to fix magically appear... I've recently got my A.C. system in working order and now quite literally have what might be considered a luxury problem, lol

When I turn the knob for temp control I get a loud clap from at least one of the HVAC vents opening or closing accompanying the change... Its in the dash. I'm not afraid to go digging for it, but i aint going to just go grab a shovel,,, digging 40 holes to find the treasure,,, if yall can provide a map... I imagine the problem has to do with foam between the vent door flaps that would seal & quiet this noise but, which door/flap and where? Where do I start digging? I don't know if I'm prepared to digg tooo deeply but am willing to see what i can do. I imagine this issue MUST decrease the efficiency of the A.C., the heater, or both, as well????

In need of some good orderly direction here. Thanks y'all!

 

JJJ
The heater unit works by blending cooled and warm air to give the desired temperature. In addition, various flaps open and shut according to Delanaire's opinion about where air should be directed depending upon variables such as temp selected, fan speed, outside temps etc etc.
What you are hearing is one of several flaps shutting, and you are hearing it because the little foam edging attached all those years ago to prevent this exact noise, has turned to dust.
The only cure is as follows:
remove steering wheel, instrument pack,
remove dash
depressurise aircon,
drain coolant,
remove centre console
disconnect battery
undo aircon valve on the firewall engine side
undo heater hoses from firewall connectors
remove front seats
with help of a friend unbolt and struggle out with the 45 kilo HVAC unit
then take the tinware apart to find all the flaps and glue on new foam strips
reverse the procedure!

In other words live with it until a matrix in the unit breaks/leaks and you have to do it!!

 

Ok. That's clear clear clear,,,! enough
fuhgeddaboudit, lol

 

Just ONE (yeah right) other thing. The definitive,,,

​​​​​​On the Del-III,,, When the button is push IN on the temp knob, IN is manual mode? Or, is IN automatic?

Oh shoot, one OTHER thing, lol...

Is there an easy service, clean or someway folks have found to test the air temp sensor in the cabin? Do folks find that they still work after allllll these years?

 

In is automatic. Out is manual.

 

The Delanair has drums that rotate, not flap doors that open and close. I suspect the noise is from something else.

 

This is bringing back some memories. Not very clear ones, though

On one of my old Jags I resurrected some part of the climate control that had been dead. I ended up with a small thud noise. After not too long it disappeared. I think my conclusion at the time was the long-dead mechanism was a bit stiff and cranky, resulting in the flap or drum or whatever not changing position smoothly but, instead, straining a bit and then sorta flopping open or closed....causing a thud. Once operation was restored and exercised a bit, all was well.

So....you might want to put the shovel in the corner. Take a wait-n-see approach before you do any digging.

Just a thought

Cheers
DD

 

Thank you!!! Really!

 

That's a super interesting bit! Never knew,,, which is the case all the time! Haha

If it's a crunchy stuck drum that gives way (thanks much Doug!) or flap or door, something (that I guess I'd imagined a bit differently) is happening. I guess I'll wait and see if it smooooths it's it's out...

For the drum,,, is there some mechanism or sealing structure that is part of the design? Close tolerance between the drum and the drum surround? Electrical or vacuum driven? It seems like vacuum in the sense that when idle is low, vacuum is high, the thud and the reaction time between the turning of the knob and the THUD,,, is immediate, almost. Slower when turned while speeding along and vac pressure is lower. I think I have that right. Anyways

I will hold off

I will be googling for images of the Del-III system some more...

Car is FULL of mystery 😂

I just removed the steel dome cover on the rear hub,,, and I've been cursing and swearing trying the tap the damn thing back on. These cars will certainly give ya something to do... Always!

 

The mark 3 system is electronic, there are motors that drive each drum to position. I've not taken one apart to see what the sealing mechanism, is, but I'd guess foam strips at the end of the opening. I had forgot until now that there are vacuum flaps for the center vent and defrost in the dash, but the blend and direction functions in the heater box itself are servo driven.

See the diagrams here: https://www.jaguarforums.com/forum/x...5/#post1646301
and https://www.jaguarforums.com/forum/x...5/#post1646306

 

Damn, Jag... Thanks!

Detail in post 5 and 6 in the first link give the best detail I've ever seen. Thanks much!

Its like,,, when I fist got this car there were so many directions I needed to go in that it seems like everything I did was GLANCED at... Now, as things are much better together and functioning, I have a chance to really spend the time and understand many of the systems in better detail. Still a lot to learn.

Y'all are great! Thank you!

Now let me go back and check out that second link!