86 VDP - Fans working on Auto and High but not Low
 

Hello,

Not sure exactly what is going wrong here - I here a faint whirring and the plastic sounding click that sounds from inside the dash when switching between modes but air does not come through the vents. It seems like an issue with the blower motor because if I leave it on low for a short while before switching to auto or full, then the air comes out significantly colder than it does when switched from off directly to high or auto. The only fuse I am aware of is the 50amp blower motor fuse in the passenger compartment under the glovebox and since it works on high and auto, I don't believe this fuse is blown. Searched the forums but didn't come across this particular problem.
(possibly unrelated but the cigar lighters aren't working either despite replacing the fuses both in the main fuse panel as well as the hidden inline brown wire 10amp fuse in the passenger leg well adjacent to the console - perhaps my problem is behind the front fascia that holds the radio bracket, trip comp. etc?)

Thoughts or suggestions?

If no LO speed but other 3 speeds are working it could either be the blower relay LO speed portion or the blower resistor LO speed portion.
Doubt it's the blowers themselves.
The whirring is the servo moving when temp switch is rotated.
Does the same problem occur at all temp settings. Move mode switch to 65 and see what happens. After a minute, move to 85 and see what happens. Check back with results.

I had a similar problem in another make(old 3 series BM), it was the blower motor resistor. It was easy to get to and cheap to replace so tried that first. Problem solved in 5 minutes and $30.
Hope yours is this simple.

Turned car on and blowers on low at 65. no air flow. waited 2 minutes, still nothing.
Moved temp. control to 85 - waited 2 minutes still nothing. So yes the problem does occur at all speed settings. Does this indicate relay or resistor failure with certainty?

Yeah, when I said its probably the blowers, I meant the electrical operating the blowers rather than a mechanical failure of the blowers which are clearly working since auto and high work.

Um, why do you not like AUTO?
My car changes fan speeds from HI to LO just fine on AUTO. In fact, I've learned it works better if I set it there and leave it.
(';')

I drive with the windows down sometimes and just want a low flow of the coldest air. Although, I basically agree and only really ever use high or auto - it's just one of those small problems with the car which irks me so frequently that I'd prefer to fix it if it's a cheap enough replacement part (or one of the hundreds of parts in my tubs in the garage that came with the car).

OK, it's all clear to me now.
(';')

I'm having a similar problem with my 82 xj6. But my problem is that the whole ac system sometimes works and sometimes is dead. Checked and replaced everything except mode switch. Studied the system thoroughly and it has to be intermittent power at the mode switch. If the on/off microswitch part of the mode switch is dodgy, then the whole system will work intermittently.
Plan is to replace the switch when I get the time, as its an all day job requiring console removal, etc.

SAE,

i your power cuts out to the entire air system, you might also double check the 50amp blower fuse in the passenger underscuttle to make sure it is clean and making contact; wouldn't want you to disassemble the whole console, etc. if its just a fuse. Sure you already thought about it but just a reminder.

John. Thanks and I have checked and replaced both fuses including bypassing the the 15 amp fuse with a new fuse holder as the contacts were weak the fuseblock.
Wish it was easy to get to the mode switch contacts so I could just check them but hidden from view. Wish me luck and will report back when I gets the courage to tear into it.

John i have the same problem with my low fan speed and have replaced my speed control switch with no joy. Did you find a solution i could look into
Ben

My problem was the mode switch for the fans. Installed another one and all works fine.

it was the blower motor resistance unit - attached are instructions on replacement and the figure 72 referred to in the instructions. hope that helps!