Had to pull the fuse to turn it off. RH Air Con Fan #5

To fix - had to BANG on it... Shut off.
What's up with that?

This cars getting to be toooooo much...

 

Each fan gets constant power and when the small bit of electronic controls on each fan fail, they will fail "ON". Fan has to be pulled and the failed component (can't remember specifics off the top of my head) has to be replaced/soldered. Lots of info in Kirby's book and the archives. I have to do this job myself, but keep putting it off.

 

Probably the controller circuit board (one on each blower motor) is on the fritz. Here's some reading

Air conditioning blower control

I can't remember what specific component on the control board is the usual culprit but just replace all of them and be done with it. There's a Darlington transistor, a diode, and a relay as I recall

The hard part is removing the blower assembly

Cheers
DD

 

Thanks Mac and Doug... And for the great link!

This isn't good news. And not something I am looking forward to. Electrical stuff isn't my strong suit (lately I don't know what is) and I have a pile of other things to be working on... Between work, house hunting and my lovely lady - where does it all fit...

So, in y'all's experience a good WACK is a temporary fix? Could it just be that the relay got hung up, or something?

 

My car's fans don't go to High speed. Low and Medium are Okay.

I gained a little experience getting the fans out from the parts car (shameless advertisement - many parts still available) but it definitely it not easy.

I have these two fans now to learn how they work.

 

On my car the fan was on very low, I almost didn't realise it until I I'd parked the car one quiet night and heard the fan on very low speed. Like you I had to pull the fuse.

That was three years ago, I haven't had heating since, which is not much fun in the lovely wet weather of the UK, lol.

I do keep meaning to do the job but other parts keep needing my attention so haven't attacked both of the blowers yet. I also don't have a garage so have to do all my work in the road which is not ideal.

Looking at the resistors I think the first one to go is the tiny ones on the board.

This isn't a problem for just Jaguars, lots of cars have the resistor packs in airflow to keep them cool. I've replaced them on various cars before, cheap part, major pain to swap though.

 

The Darlington transistor is the component that fails. That is the electronic switch that controls the current.

Brad, if you don't have high speed there is a relay inside the blower case that provides 12V direct to the blower motor and bypasses the variable speed circuit, so that relay is probably bad or has corroded contacts. To repair either the variable speed circuit, or the relay, the blower assembly has to come out. The link Doug referenced tells you all you need to know, the parts are available from Digikey. It's not too bad a job to do.

 

I'm happy to say that this issue never reappeared. A one shot deal... strange...

The other day - a while back now - I started the xjs and the starter didn't disengage... God awful feeling. Even after turning the key off. Had to disconnect the battery. Never happened before that, hasn't happened since.

Gremlins

 

Jay Jay,
Feel your pain brother. My '93 has more electrical curiousities than I can list here. Likewise, fan motors work, then don't. I have to turn on the running lights to get the radio to come on. Driver door window works when I flip the switch opposite to the correct direction, then doesn't unless I flip it back. I have disconnected the ground cable on the battery so often I installed a "quick disconnect switch".
Feel your pain
Dave in AZ