Heater Blower not working - HELP PLEASE
 

Hi Guys,

I have a 97 XK8 RHD. I noticed that the heater/AC didn't work too well. When picking the car up from the MOT I mentioned it to the guy, he said, probably gas is a bit low (re AC not very good) and perhaps one of the fans is not working which would be why it doesn't blast much air.

So, I checked the car over, sure enough, driver's side blower is not working.Checked the fuse, all good. Purchased another blower unit complete from eBay, went to install it tonight, but still no good. With both fans on the foot well, I can see they're not working when plugged in. Found the blower relays under the glovebox on the passenger side and swapped them over - still no working blower with either unit and the passenger side one still works - so I don't think it's a relay.

Any ideas? Please, this is really stumping me and I could do with some cool air this summer and some warm air when the winter comes.

Many thanks in advance.

The blower is definitely NOT running - it isn't simply the servo motors not moving the flaps to direct the air?

If the motor is not running and you have eliminated both fuse and relay, it has to be either a break in the harness or a fault with the A/CCM (Air Conditioning Control Module).

https://cimg4.ibsrv.net/gimg/www.jag...e573bf86cc.jpg


As you don't yet have sufficient posts to be able to download attachments from the forums, I'll include the pinout list here:

https://cimg5.ibsrv.net/gimg/www.jag...6960409793.jpg


This is readable on my 32 inch monitor - I hope you aren't viewing the forum on a smartphone. :icon_lol:

Graham

Graham, Many thanks for the reply. I can see that the fan is not spinning. Also the replacement fan is not spinning when plugged in. Just to help me eliminate the relays, can you tell me the location of the relays and what they look like? I found two blue relays up under the glovebox and swapped them over, but it made no difference.

I find it strange that it all looks good up there, no water damage etc, no chaffed wires, so where might the harness damage be?
Also, would the AC Module just decide to not output to one fan and everything else be ok?

Thanks in advance for your help.

Matt,
You did check both 20A fuses? :icon_hide:

There's one for each blower: F11 in the respective side fascia fusebox. Unfrtunately it's not straightforward to check the blower unit out of the car as there are control lines as well as the power feeds.

It is entirely possible for the module to let go just on one side.

Make sure you disconnect the battery if you are disconnecting any plugs on any module.

Hi there, yes checked the fuse on the driver's side - that's good. Didn't check the fuse on the passenger side, since that fan is working. Basically dropped the blower unit down complete and looked inside, fan not working. Pulled the plug from this and connected to the replacement fan unit, also complete, and that's also not working.

Matt,

You've identified the relevant relays:

https://cimg9.ibsrv.net/gimg/www.jag...f613789a45.jpg

Thois is from the Vehicle Care Handbook. If you don't have copies of any of the handbooks for your vehicle, you can download them as PDF's from this thread:
https://www.jaguarforums.com/forum/x...006-faq-67827/

Graham

Many thanks Graham for the confirmation. So looks like I need a module, or I am unlucky enough to have bought a defective fan unit... I'll have another play.

Update - still not working.

After poking about the wiring diagrams for a bit and finding my multimeter, I have checked the outputs at the plug where it goes into the blower unit. All signals are present and correct, but no operation. The new unit still does not operate when plugged in. Since it's laying in the footwell, I can clearly see that the fan is not rotating.

I have contacted the seller and organised a return. I think I was unlucky and got a defective unit from everybody's favourite internet auction site. Once back with him, he will check his end and hopefully send me a replacement.

Anything else I should have checked? Am I right in thinking that the power transistor (attached to the heatsink in the duct) is there to regulate the speed of the fan dependant on voltage from the control module? i.e. when turned fully up, the fan should work but perhaps won't respond to speed control if the power transistor is not working? Otherwise, how would I identify if it's the fan or the power transistor? Jump some voltage to the fan terminals themselves?

Many thanks in advance.

You are thinking along the right lines.

If you can access the motor + & - terminals with you meter prods with the fan unit plugged in, or get to connection 1 in the diagram and the U/W (blue/white) wire on the connector, check for a voltage difference across them. More than a couple of volts difference points to the fan motor, zero or close points elsewhere.

That could be the power transistor, although there appears to be some form of breaker depicted between it and the motor connection 1

What is the voltage between ground and the Green wire? It should be less than 1 volt, but greater than zero.


https://cimg9.ibsrv.net/gimg/www.jag...9efda0d37e.gif

Please post back what you find.

Thanks to everyone for your help. So after lots of prodding about with a meter verifying that I had all the voltages where I should have them at the plug to the blower unit, I decided that it must be the voltage regulator/power transistor. New part arrived at the weekend. Last night after much poking about in the footwell and struggling to work out how to remove the unit, I decided to give it one last test before I removed something I couldn't get back in. Plugged in the unit, and it worked!!! I was quite shocked at this and pulled at wires here and there to work out what was going on, seems the connection to the motor itself was not quite plugged in properly. Not sure how this could become disconnected, but there you go. Problem solved, lots of air coming out now.

Thanks again all.

Thanks for the feedback & glad you got there.

Sometimes unplugging and plugging back in can wipe the contacts clean enough to re-establish a connection. Would be worth going through and using some electrical contact cleaner on the various plugs & sockets.