94 XJ40 blowers not working
Member
Joined: Jul 2012
Posts: 65
Likes: 17
From: Texas
Blowers not working
Step 27 - Now you need to put evey things back. Do the same way but go backward but you need to test it to make sure switch work before installation every things back. Use DOM test continuety both terminal of micro switch by turn on AC Fan.
Thread Starter
|
Veteran Member
Joined: Sep 2012
Posts: 2,726
Likes: 1,910
From: Victoria BC Canada
Thanks so much Zenidyle, picked up a micro switch from Radio Shack today and ordered a new clock lightbulb, might as well fix everything while the center console is out.
If the blower system still doesn't work properly after I change the micro switch I'll be following on to the next steps, getting new relays and rebuilding the blowers and/or speed control electronics.
Thanks again for the fantastic detailed posts
cheers
If the blower system still doesn't work properly after I change the micro switch I'll be following on to the next steps, getting new relays and rebuilding the blowers and/or speed control electronics.
Thanks again for the fantastic detailed posts
cheers
Member
Joined: Jul 2012
Posts: 65
Likes: 17
From: Texas
Good lucks. Let us know what your result.
Thanks so much Zenidyle, picked up a micro switch from Radio Shack today and ordered a new clock lightbulb, might as well fix everything while the center console is out.
If the blower system still doesn't work properly after I change the micro switch I'll be following on to the next steps, getting new relays and rebuilding the blowers and/or speed control electronics.
Thanks again for the fantastic detailed posts
cheers
If the blower system still doesn't work properly after I change the micro switch I'll be following on to the next steps, getting new relays and rebuilding the blowers and/or speed control electronics.
Thanks again for the fantastic detailed posts
cheers
Thread Starter
|
Veteran Member
Joined: Sep 2012
Posts: 2,726
Likes: 1,910
From: Victoria BC Canada
Did the micro switch replacement and changed out the burned out bulbs in the clock today....blowers still as they were, not working :-( so it's on to the next stage, will keep you up to date on my progress!!
Thanks once again Zenidyle for the detailed instructions and happy new year!
Thanks once again Zenidyle for the detailed instructions and happy new year!
Thread Starter
|
Veteran Member
Joined: Sep 2012
Posts: 2,726
Likes: 1,910
From: Victoria BC Canada
Fixed - sorta!
Hi Guys,
Update on the blower repair on my '94 XJ40
After replacing this switch I checked for 12v on the driver's side blower brown connector at the blue/brown wire and the wire was dead.
According to the wiring diagram in Haynes, this wire is always powered and connects directly to the fuse box in the LH footwell.
When I probed the fuse, I had power on both sides of the fuse so I figured I had either a broken wire or the problem was at the fuse box, so I unplugged the connector at the fuse box and did a continuity check on the blue/brown from there to the brown connector at the blower. The wire checked OK.
I removed the fuse box and took out the circuit boards. They looked clean at first glance, but on close inspection I spotted a cracked solder joint right next to the blower fuse connector.
After re-soldering and re-installing the fusebox I had power on the brown/blue and the blower started working again - but only on high speed, so I still have to pull that blower and fix the darlington transistor, relays etc to get low and medium speeds.
The RH side was also not working at all so next I pulled the RH fusebox, found the very same problem - cracked joint at the blower fuse. Re-soldered it and when I re-installed it, to my surprise, the RH blower fired up and worked on all speeds - BONUS!!!
Now I don't have to worry about disarming and removing that passenger airbag and blower assembly!!
So next, it's pull the LH blower and fix the speed control.
Nice to have heat again!!
Thanks to all who helped out with the diagnosis/solutions
all the best,
Update on the blower repair on my '94 XJ40
After replacing this switch I checked for 12v on the driver's side blower brown connector at the blue/brown wire and the wire was dead.
According to the wiring diagram in Haynes, this wire is always powered and connects directly to the fuse box in the LH footwell.
When I probed the fuse, I had power on both sides of the fuse so I figured I had either a broken wire or the problem was at the fuse box, so I unplugged the connector at the fuse box and did a continuity check on the blue/brown from there to the brown connector at the blower. The wire checked OK.
I removed the fuse box and took out the circuit boards. They looked clean at first glance, but on close inspection I spotted a cracked solder joint right next to the blower fuse connector.
After re-soldering and re-installing the fusebox I had power on the brown/blue and the blower started working again - but only on high speed, so I still have to pull that blower and fix the darlington transistor, relays etc to get low and medium speeds.
The RH side was also not working at all so next I pulled the RH fusebox, found the very same problem - cracked joint at the blower fuse. Re-soldered it and when I re-installed it, to my surprise, the RH blower fired up and worked on all speeds - BONUS!!!
Now I don't have to worry about disarming and removing that passenger airbag and blower assembly!!
So next, it's pull the LH blower and fix the speed control.
Nice to have heat again!!
Thanks to all who helped out with the diagnosis/solutions
all the best,
Joined: Aug 2011
Posts: 619
Likes: 210
From: Wilmington, DE
Glad you found the fuse boxes as the fault (at least for the right side). I had forgotten about that one. I saw it one time at the dealer, I think older dealer techs saw that concern more. Great investigating on your part!
Senior Member
Joined: Feb 2011
Posts: 344
Likes: 47
From: NW Alabama
Not to highjack your thread but I thought I'd throw in something I found as well on a 94 XJ40. The driver's side blower would not work. So I assumed that it was the resistor pack and never really checked anything. Got a good used blower assy and installed it but had the same problem. I had power at the fuse box and coming out of the fuse box but no power to the plug. The wire was open somewhere crossing up and over. I repaired the wiring and fixed the problem. Glad you found your problem as well.
Senior Member
Joined: Feb 2014
Posts: 281
Likes: 50
From: Australia
Thanks Zenidyle, I rekon this may be the answer to one of my problem.
the illustrations and explanation were excellent.
I will take a look at the micro switch when I get the chance and see if I can fix my blower...... will keep you posted once done
the illustrations and explanation were excellent.
I will take a look at the micro switch when I get the chance and see if I can fix my blower...... will keep you posted once done
Junior Member
Joined: Apr 2015
Posts: 7
Likes: 0
From: Manchester, NH
I am new to Jaguars and to this site. Just bought a 91 xj6 for my wife to play with. The previous owner babied the thing. I am getting a real kick out of people sharing all the Jag secrets. Cool.
Joined: Feb 2014
Posts: 20,428
Likes: 15,215
From: Crossroads of America
Hi Can do it,
Welcome to the Jaguar Forums! It's great to have you with us!
Please visit the New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum and post an introduction so we can learn something about you and your Jaguar and give you a proper welcome.
Also, if you don't find the answer to your blower motor issues by searching this forum, try the XJ40 eBook at the Jag-Lovers forum, which has an excellent section on the Air-con blowers. You will probably have to register and log in to view it, but it's free and there's a ton of XJ40 info in the archives there:
Jag-lovers' Ebooks
Cheers,
Don
Welcome to the Jaguar Forums! It's great to have you with us!
Please visit the New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum and post an introduction so we can learn something about you and your Jaguar and give you a proper welcome.
Also, if you don't find the answer to your blower motor issues by searching this forum, try the XJ40 eBook at the Jag-Lovers forum, which has an excellent section on the Air-con blowers. You will probably have to register and log in to view it, but it's free and there's a ton of XJ40 info in the archives there:
Jag-lovers' Ebooks
Cheers,
Don
Junior Member
Joined: Nov 2013
Posts: 17
Likes: 3
From: Sedro Woolley, Wa 98284
Thanks for a great write up. It is good timing for me as I am about to tackle the blowers in my 1988 again. Mine does something other then just run on high. When I turn mine on it blows at what sounds to be a moderate rate for a few seconds then steps down to very low rate. I have already replaced the control panel with no change. I know from pulling fuses that only the left blower is working at all. So I going to go at the passenger side blower next. Thanks again for the very good info.
Senior Member
Joined: May 2012
Posts: 492
Likes: 249
From: Mobile, AL USA
Thanks for a great write up. It is good timing for me as I am about to tackle the blowers in my 1988 again. Mine does something other then just run on high. When I turn mine on it blows at what sounds to be a moderate rate for a few seconds then steps down to very low rate. I have already replaced the control panel with no change. I know from pulling fuses that only the left blower is working at all. So I going to go at the passenger side blower next. Thanks again for the very good info.
dbeck54,
You may want to consider pulling your fuse boxes and ensuring all of the solder points are good. Sounds to me like you have a variable in supply and I would be suspicious of the fuse boxes.
I just realized the date of your post, so how did things turn out with the blower assemblies?
Member
Joined: Sep 2015
Posts: 41
Likes: 20
From: Saskatoon, SK, Canada
Thanks for the great info and process. I would like to add one thing about micro switches. They have a life span as you have noted. They will often fail with a low resistance but not low enough to be detected by the control logic. For instance it is common that the switch will have 0 or <1 Ohm when new and after several years start having 5-7 Ohms. This continues to get worse with use. Note that when checking the switch actually has 0-1 Ohm. Anything greater means it is on the way out. They are cheap and readily available at any electronics supplier. Ones made offshore will last less than a name brand such as Omron or MicroSwitch or? Why do the job twice? I have experience with doing jobs twice. Ron.
Thread Starter
|
Veteran Member
Joined: Sep 2012
Posts: 2,726
Likes: 1,910
From: Victoria BC Canada
I just read Norman Crane's explanation of the blower speed control system on another forum and for future reference, include it here:
Larry
Let me try and explain the use of the Darlington pair transistors as used on the blowers in our motors.
The Darlington pair is actually two transistors encapsulated in one housing, hence the name, the first transistor of the pair cascades its output onto the input of the second, this is done to increase the high current that can be switched (This relatively high current is why the transistor cans themselves are mounted on a hefty heat sinking base).
A transistor is in fact a controllable, variable relay, but instead of just having two states, on or off, it has various stages of open from zero to max with all the values in-between.
In the blower circuits the first transistor of the pair is triggered by the “Climate Control Microprocessor” the subsequent output of the second is fed directly to the blower.
We have one Darlington pair for the right blower and another for the left blower. The microprocessor receives the settings from the climate control panel switch of low / Med / High speed and depending on the ambient temperature regulates the fan speed via the Darlington pair, however, in the case of the high speed setting a relay is triggered which effectively bypasses the Darlington pair and drives the fan directly.
So the microprocessor controls the fans at low or medium speed via the Darlington array and then directly when on high speed, which is why the fans may work on high speed but not on low or medium if the Darlington has failed.
When changing out the Darlington pairs I cannot stress enough the care that must be taken to ensure that they are electrically isolated from the heat sink plate, but at the same time thermally “connected” via the mica washer and a liberal layer of white thermal conducting paste. They can get quite hot when in service.
The Darlington pair is actually two transistors encapsulated in one housing, hence the name, the first transistor of the pair cascades its output onto the input of the second, this is done to increase the high current that can be switched (This relatively high current is why the transistor cans themselves are mounted on a hefty heat sinking base).
A transistor is in fact a controllable, variable relay, but instead of just having two states, on or off, it has various stages of open from zero to max with all the values in-between.
In the blower circuits the first transistor of the pair is triggered by the “Climate Control Microprocessor” the subsequent output of the second is fed directly to the blower.
We have one Darlington pair for the right blower and another for the left blower. The microprocessor receives the settings from the climate control panel switch of low / Med / High speed and depending on the ambient temperature regulates the fan speed via the Darlington pair, however, in the case of the high speed setting a relay is triggered which effectively bypasses the Darlington pair and drives the fan directly.
So the microprocessor controls the fans at low or medium speed via the Darlington array and then directly when on high speed, which is why the fans may work on high speed but not on low or medium if the Darlington has failed.
When changing out the Darlington pairs I cannot stress enough the care that must be taken to ensure that they are electrically isolated from the heat sink plate, but at the same time thermally “connected” via the mica washer and a liberal layer of white thermal conducting paste. They can get quite hot when in service.
Thread
Thread Starter
Forum
Replies
Last Post
philwarner
XJ6 & XJ12 Series I, II & III
16
Sep 5, 2015 10:05 AM
Chet Ramnarain (bozzner)
XJ6 & XJ12 Series I, II & III
5
Sep 3, 2015 12:21 PM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)