Master
SupporterThe vehicle is a 91 Range Rover Hi-line and yes I know this is one of most common problems affecting heater fan controls but having been over countless websites and forums, I cannot find a simple, effective explanation of how to rectify the problem, namely that the aircon/heater fan works only in the "off" and "L" positions. ll and lll do nothing.
Please read carefully and consider:
1. The resistor pack under the cowl and the relay under the left side panel in the cab have been replaced with new ones
2. The control switch was removed and had evidence of burning on the pins and plastic connector. It has been removed and the wires in the loom extended with 150mm long extensions to allow better access.
3. A multimeter indicated that the switch had continuity only between one of the top two pins and one of the three lower pins. There was no reading for the other pins so this assumes the switch itself is defective
4. Pending arrival of a replacement 4-position switch, it has been replaced with separate on/off switches, one pin of which is connected to the twin black/white wires (the only ones that actually supply any power).
5. Only one wire in the loom has continuity with the resistor pack so that has been connected to the other pin on one of the switches This allows the blower to operate but only on one speed (low). That suggests the fan motor itself is working correctly or it would not work at all
6. A new wire was run from a second switch to the resistor pack, but regardless of where it was spliced into the wiring, it did not activate the fan motor. Why??
7. The red wire in the loom is dead - no power and no continuity with the resistor pack. Is this critical to the operation? OR is there some internal connection in the old 4-position switch that is not being replicated with the new separate switches?
Sorry to make this a long-winded post but I’m stuffed if I know what to do next. If anyone really does know the answer. Please advise
burned_switch (600 x 432).jpgextended wiring (600 x 463).jpg
Master
SubscriberI will start off by saying that i am in no way an electrical guru. First off have you tried by passing all the wiring and using a jump wire to the fan motor and see if it actually goes flat out. Next step have you checked your earth wire / or identified it in your wiring. I, in no way being critical but i do one thing at a time. fuse check, voltage check, earth check. Good luck. Baz
Master
SupporterThanks Baz - I appreciate your suggestions, though I still hope to get a response from someone here with specific knowledge of how the system works and precisely what steps to take. However, in answer to your questions, no I have not jumped the fan direct from the battery and yes, it makes sense to try that to confirm the fan itself will run at full speed. Let's assume that will work - but it does not solve the fan speed problemsOriginally Posted by Bazzle218
As explained in my initial post, wiring may well be the problem, but without precise knowledge, I do not know which wire is supposed to connect to what and which must carry power.
ForumSage
I have no knowledge of later model fans but be aware the earlier ones had plain bronze bushes on each end of the drum fan that would cause issues from lack of lube after 20 years.
Rebuilt the whole unit ('81) that's in my 74 when I discovered this. The fans in the early ones use quite a lot of power and if the bearings are dry they're going to warm the wiring.
From memory it has an inline fuse, separate from the stock total of 3 puny ones on the firewall.
DL
LordRover
SubscriberI have responded to the other thread, but thought this was worth mentioning. For frustrating jobs like this it is best to be systematic. I would always be dragged down one rabbit hole after another chasing something i thought was the issue and lose sight of the bigger picture. These days I try to eliminate each part of the puzzle in turn. With this one I would have started with the fan itself and worked back.. In order to make this easier I purchased a device called a PowerProbe. For DYI it is genius. Sure, pros use higher tech kit, but for me it just does it.
Heres one: Power Probe PPROKIT01 Red Professional Testing Electrical Kit : Amazon.com.au: Home Improvement
but there are others, some way cheaper. Combined with my kinda high end multimeter and a polarity sensing test light you are set for most issues like you faced.
Just refrain from using any of them on any SRS system.... Yeah, I know, but you may not always be playing with Classics.
JayTee
Nullus Anxietus
Cancer is gender blind.
2000 D2 TD5 Auto: Tins
1994 D1 300TDi Manual: Dave
1980 SIII Petrol Tray: Doris
OKApotamus #74
Nanocom, D2 TD5 only.
Master
SupporterFinally got it working using toggle switches instead of the OEM control switch. The hard part was identifying the wiring and getting power to the right places.
If anyone is interested, I have now prepared a document explaining the various stages of checking and how I engineered a workaround solution.new_switches_installed (600 x 302).jpg
ForumSage
Came across this by chance today:
1992 RRC Replacing Heater Blower Motor Resistor | Range Rovers Forum
Someone on here did something very similar a few years ago.
DL
YarnMaster
Yes please, I'm interested.
D4 MY16 TDV6 - Cambo towing magic, Traxide Batteries, X Lifter, GAP ID Tool, Snorkel, Mitch Hitch, Clearview Mirrors, F&R Dashcams, CB
RRC MY95 LSE Vogue Softdash "Bessie" with MY99 TD5 and 4HP24 transplants
SADLY SOLD MY04 D2a TD5 auto and MY10 D4 2.7 both with lots of goodies
YarnMaster
Yes please, I'm interested. And a good one for the archives perhaps?
D4 MY16 TDV6 - Cambo towing magic, Traxide Batteries, X Lifter, GAP ID Tool, Snorkel, Mitch Hitch, Clearview Mirrors, F&R Dashcams, CB
RRC MY95 LSE Vogue Softdash "Bessie" with MY99 TD5 and 4HP24 transplants
SADLY SOLD MY04 D2a TD5 auto and MY10 D4 2.7 both with lots of goodies
Master
SupporterHi Gavin
Here is the PDF version of the new article - sorry about the file size:
Cheers
Alan
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