"96 XJS - Blower motor works in the high speed function (3 and Defrost) but not in the low speed functions (1 and 2). Any suggestions for where to look to get the low speed blower to work again?

 

Are you suuure it won't work? Even on Top Gear's early 90s review Clarkson called the blower settings useless and deafening.

Medium on my car only seems to casually move hot air behind the seats. 'Medium' is low and low is useless.

 

VancouverXJ6, Thanks for your reply. Yes, the two lower settings used to work, then started working intermittently, then just stopped. I know the flaps in the heating unit work, because with the car in motion, and the fan on 1 or 2, I still get ventilation in both heating and cooling mode. I know (?) there are two fans - perhaps the low fan stopped working. I want to know if maybe there is a relay that controls those functions. When it was working, the low speed fan did not squeal or make any "bad" sounds. Are the fans accessible without major deconstruction?

 

As far as I know your car will have the Delanair Mk II system although, by 1996, it underwent some changes I'm not familiar with and I think it was being manufactured by Valeo rather than Delanair itself.

If I'm right then there are no relays that control blower speed. It appears that the blower speeds are commanded by the climate control ECU, in response to the mode switch or the 'automatic' function of the system. I suspect this is done simply by reducing voltage to the blower motors, and internal function of the ECU.

I'd begin by checking all relevant connections....which itself isn't always easy. the back of the mode switch is not easy to check and there are numerous connection behind the dash, some of which are hard to reach. However, I have repaired a couple of these system by doing so. I've found several connections loaded with green corrosion. Some of the connectors are quite tiny so they're not easy to clean. Also check the sywstem grounds. On the older models, at least, there are ground points on the two vertical dash supports that you'll see on either side of the big heating/AC unit itself

Sorry I can't offer anything concrete

Cheers
DD

 

My problem was the opposite. Low speed only. No AUTO, HIGH or DEF.
After mentioning that when I jumped the terminals at the main relay, I could get all the speeds to function, the suggestion was to check the mode switch.
This may be the hard way, but it is the only way I know.
Maybe someone else will chime in with a easier way.
To remove the mode switch, the center console has to be removed.
Remove the radio, and the radio panel. After removing the front screws of the radio panel, go to the right side of the radio panel and remove the 3 nuts that hold a triangular panel in place. It attaches to the front radio panel
Remove the lower bolt of right hand side dash strut and move it aside.
Do not remove the the two screws at right hand side of the mode switch. Those 2 screws only start to disassemble the mode switch.
These are tiny screws. (use a magnetic head screwdriver)
The mode switch consists of 4 micro switches. One for each speed.
If you do not want to remove the mode switch at this time, you now have proper access to all of the connectors behind the mode switch.
Remove them one at a time and clean the connectors keeping your fingers crossed.
I replaced the mode switch with a spare I had.

 

Looking at what is said above my only puzzle is that these blowers boxes don't seem to have a flap at the bottom only the one at the top and seem to be an otherwise sealed unit. Maybe these are older one put in a Series 2 to replace damaged newer ones in the past? I'll have another go at opening them today.

 

If you discover a cure, I'd like to know. After 15 years of only "high" working on the fan switch, I realized in a convertible the seat heater is a the best source, even with the top down! "High" works the defrost nicely. Thankfully, in AZ there's not much demand.
As for A/C, it's a convertible and British and an R12 system. Just no point worrying about it, lol.
Dave in AZ

 

Welllllllllllllll best to let Grant or Doug comment on something like this, your level of difficulty will be measured in number of Beers, infer from that what you will.