So, now that I’ve been informed about the vacuum advance issue on the distributor, I now figured it’s time to investigate why the radiator coolant fan did not come on yesterday when the weather was warm and the car ran on the dynomometer at the inspection facility for awhile. Although the temperature gauge stayed close to 90, by the time I got back to my garage and slowly backed it in, temperature crept up beyond 100 but the fan did not come on.I switched out the relay to another one, but fan still did not come on. Today I decided to spray the motor contacts with electrical contact cleaner hoping this would solve the issue. Although the service manual says there is a block connector, it looked to me like the fan motor wires just meet up with others, so I decided (foolishly) to remove the cover of the fan motor and that’s when all hell broke loose. For longer than I’d care to admit, I spent a whole lot of time unsuccessfully trying to put the motor back together. What to do? The good news is the SNG catalog shows the motor part CAC2047 in stock at a reasonable price though I’m at a loss to understand why my motor seems to meet up with a group of other wires. I don’t think this has ever been replaced or altered. I suppose I’ll have to have another look. Perhaps I’m missing something.In theory, is it reasonable to assume that replacement of the fan motor CAC2047 along with relay part DAC1028 would be the route to follow? As always, advice greatly appreaciated.
The connection between the motor, sensor and car wiring is somewhat intricate, Mel - and may vary with types…
As the fans/motors spin in the air flow when not engaged they generate electricity. To avoid ‘contamination’; relay(s) and possibly diode(s) may be used - which requires extra wiring…
Without the original wiring diagram, tracing connections and wiring is cumbersome. Without some certainty as to the cause of your problems, both testing and remedial actions pose a problem…
Trace the wires to identify connections - and see what is what…?
Hello again Frank
After going through the pages of the factory workshop manual and factory parts manual. I have now reached the conclusion that if I had not removed the cover of the fan motor and destroyed it, I possibly could have avoided considerable headache and expense by looking more closely at the factory service manual. I now think the coolant motor and relay may not have been the problem.Looking closer at the factory books, I now think the problem of the fan not having come on under hot conditions could have been caused by the failure of the item known as the "fan themostat switch inconveniently located at the bottom of the radiator and according to the service manual would be requiring draining the coolant from the radiator to be able to replace the thermostatic switch shown in the parts SNG catalog as DAC3061. What is most peculiar is that part number is not listed in the factory parts book, and the SNG book shows it ‘on back order.’ On the plus side, I do have the fan blade still attached to the old motor I messed up, as well as two thermostat relays with the five pin connectors. A new fan motor is on the way from SNG, and instructions to drain the radiator don’t really matter since the car is close to being due for a coolant change. The mystery to me is the thermo switch shown in the SNG catalog, part DAC3061 is not listed in the factory parts manual.What would you recommend? Thanks for your advice as always.
Mel R.
Are you running the stock yellow driven fan or the later black XJ-S variant?
I put the latter in all my customers cars, and with a properly cleaned out stock radiator, the aux fan never comes on, unless it’s brutal hot or A/C is selected.
The fan is $75.00, a new heavy duty clutch $35.00. You definitely don’t want that aux fan as any integral part of your day-to-day cooling system.
I have the stock white (which turns yellow as it ages) fan with a relatively new clutch. Car stays close to 90. It’s just that several days ago Car was on dynamometer for 15 minutes for smog check on a warm day after which I drove home in heavy traffic at which time gauge went up a notch close to 100 briefly then dropped to 90 when traffic moved. I was concerned the fan should have come on but didn’t. I have replacement relay and another fan motor on the way as I am averse to risk of possible risk of overheating if subjected to hot weather with slow traffic again. Today I saw in the factory manual reference to the replacement of the Thermal fan sender which would require draining the radiator. Am I overthinking this I was thinking it might be an idea to have the switch replaced next time the coolant is drained and replaced.
The updated black XJ-S fan is much more efficient than the original unit currently in your car, and the stock clutches (Beck Arnley et al) are not great at locking in as the temp creeps, as they were designed with quietness in mind, vs. efficiency.
As for your aux fan, motors generally last longer when run on a constant basis. The thermal couple switch in the radiator can easily be bypassed by bridging the two wires together. It’s a “belts and suspenders” approach to put an inline fuse between those two wires, but in your climate, there isn’t anything wrong with letting it run constantly.
There was an infamous former shop in town that used to put a piece of old extension chord, between the coil and the aux fan, whilst telling customers “they all run hot”, meanwhile the fan clutches would windmill and the lower half of the radiator fins were clogged with debris . They would of course be handsomely charged for said expertise .
In addition to, however, the main system needs to be at 100%, so seriously consider updating your driven fan.
I may be barking up the wrong tree, Mel - I thought you had all electric fans, not ‘main’ mechanical and an auxiliary electric…?
In the latter case; Jaguar installed the factory aux to come on when AC was turned ‘on’. Which may explain that that thermal switch not being mentioned. There is no way of knowing what a PO might have done - though I may give a dog a bad name…
It may be that that the eventual aux fan does not come on because the fan has lost power from the AC rather than a failure of the switch? Basically, any switch with a preferred trigger point will do - easier if the dimension/thread matches the present one…
Some thoughts; your car is indeed running a bit hot - though certainly not alarmingly so. A ‘hot’ thermostat, 88C, may fitted which would explain a fairly steady 90C gauge reading. Another is a thermostat partly stuck open - it would cause slow warm-up, higher running temps and some temp variation depending on load. Yet another is of course impaired cooling for other reasons…
As the gauge is not really a precision instrument, and is slow moving. I suggest you get a cheap infrared thermometer - a very useful gadget for cooling anomalies…
Frank
I may not have described my situation clearly enough. I don’t think PO has done anything improper with this car I’d say it’s one of few 1986 cars still out there as pristine as this one mechanically & cosmetically. My car isn’t running hot overall . It is fitted with 82 degrees thermostat. Most of the time gauge just below 90 or at 90 straight up. When the smog technician ran the engine in a closed space on the dynamometer close to 20 minutes and the gauge ran close to 100 I was concerned the auxiliary fan did not come on I was worried about the dangers of engine overheating and the possible damage which could result. Here in the US the fan does not come on when the a/c is switched on. That only occurs on v12 models. So since I’m due for a coolant change soon, I was thinking when the radiator is drained it might be an opportunity to replace that thermo switch at the same time. Perhaps I need to think about it more. As always thanks for your replies.
Mel R
Are you sure you broke the fan? The cover is just a cover, I’m pretty sure that if you take the fan out of the car things will be much easier to see and fix when on the bench.
I’ve never seen a six-cylinder Series III configured with a tie-in between the AC compressor and the electric fan. I’m pretty sure nobody else has, either, unless owner modified
Here a pic from the parts catalog. DAC3061 looks correct
In principle, Mel - the engine should run at thermostat temp at ‘all’ times, so ‘90’ is ‘hot’ in this respect. Apart from reasons mentioned; an engine will run hot if the ign timing is incorrect - usually to low - so you should check timing…
It is still relevant to check actual temp (IR) to verify the gauge. 90 - 100C, or more, is not actually harmful to the engine - just a warning of possible cooling issues…
And Doug is of course perfectly right; the aux fan on the 6 is thermostatically controlled - I just tried, against better knowledge, to explain your statement the thermoswitch’s absence from the parts catalogue…
It’s easy to check if the motor itself is OK by jumpwiring 12V to it - then pursue its non-running issue, one way or another…
Not all of the senders are accurate. I once swapped a wiring loom and the reading went up 5° or so. There was a resistor included in the loom, put that back in, voila back to 90.
. They would of course be handsomely charged for said expertise 
.
