Heater wiring

[ManyMinors]

On my late Minor 1000, the feed for the heater (green wire) is connected to the wiper switch

[svenedin]

On my late Minor 1000, the feed for the heater (green wire) is connected to the wiper switch

Reviving an old thread but my late Minor also had the heater green wire connected to the wiper switch and I found another thread saying the same thing. I am absolutely sure about this on my car because I took photographs before removing the old loom. My heater and wipers worked either on their own or with both switched on at the same time (but the wiper self-park did not work, a separate issue perhaps). I installed a new loom and I followed the workshop manual to achieve this except, I connected the heater green wire to the wiper switch (which is not according to the wiring diagram in the workshop manual. The wipers worked OR the heater but not both switched on at once. I also could not find a female spade earth connection in the new loom which is how the heater earth wire connected before.

The workshop manual shows the heater green wire joining a bullet connector not a spade connector as mine had. I gave up trying to work out what on earth was going on so I changed the end of the heater green wire to a bullett and found a vacant female bullet connector of other green wires (as per manual). Then I used a bolt in the floor of the glovebox metalwork surround (where there are lots of existing holes) to make an earth connection to an eyelet on the heater black wire (I could have used the bulkhead stud for the heater bracket instead but the wire may have been less tidy). Everything works fine now but I am still not satisfied that I can't work out why the heater green wire was connected to the wiper switch!! It's a crazy arrangement surely because the wiper switch just switches the earth for the wiper motor although it does have a live side from the heater green wire (returning to switch as black/green). It did work before but it would not work with the new loom. Very strange. Anyway, of academic interest only to me now as I have lots of other jobs to do on the car and it works.

Stephen

[svenedin]

I think I have solved this from reading the supplemental instructions at the back of the workshop manual for fitting a late heater.

These instructions (see picture) say to connect one of the wires from the heater to a spare socket in a snap connector of GREEN wires behind the facia and the other wire to the earth side of the wiper switch. Why the instructions say to cut the Lucar connector off to connect it to the switch I do not understand because the switch has spade terminals. Anyway, the instructions do not specify the colour of the wire to connect to the wiper switch earth side although since this is earth one would expect it to be the black wire not the green one! The fan motor in my car (and I suspect most late heaters) is permanent magnet type so if the polarity is reversed the fan spins the wrong way.......and having bench tested this it blows considerably less air spinning the wrong way. If of course the car's polarity was changed it would spin the right way.......

So all this does is use the wiper switch as an EARTH point and as such it is perfectly reasonable because the wiper switch works by making and breaking the wiper motor connection to earth. Of course, the heater wire must be connected to a terminal on the switch which is permanently earthed NOT a terminal that is only earthed when the switch is on.

Stephen

IMG_1533.jpeg (4.3 MiB) Viewed 1502 times

[svenedin]

Off to fiddle with the heater wiring now.....

[geoberni]

Why the instructions say to cut the Lucar connector off to connect it to the switch I do not understand because the switch has spade terminals. Anyway, the instructions do not specify the colour of the wire to connect to the wiper switch earth side although since this is earth one would expect it to be the black wire not the green one!

They probably say to remove the Lucas connector because it's the Workshop manual 'modification' instructions for aftermarket use at a Dealer Workshop.
Aftermarket fitment of the heaters was most likely to be carried out on a Pull Switch car, which have screw terminals.
Only the latter Flick Switches have spade terminals, and I'm guessing most if not all of them left the factory with a heater of some type.

[svenedin]

Why the instructions say to cut the Lucar connector off to connect it to the switch I do not understand because the switch has spade terminals. Anyway, the instructions do not specify the colour of the wire to connect to the wiper switch earth side although since this is earth one would expect it to be the black wire not the green one!

They probably say to remove the Lucas connector because it's the Workshop manual 'modification' instructions for aftermarket use at a Dealer Workshop.
Aftermarket fitment of the heaters was most likely to be carried out on a Pull Switch car, which have screw terminals.
Only the latter Flick Switches have spade terminals, and I'm guessing most if not all of them left the factory with a heater of some type.

Yes I thought that too but these are instructions for the late heater. I thought flick switches were in use by then?

[geoberni]

Why the instructions say to cut the Lucar connector off to connect it to the switch I do not understand because the switch has spade terminals. Anyway, the instructions do not specify the colour of the wire to connect to the wiper switch earth side although since this is earth one would expect it to be the black wire not the green one!

They probably say to remove the Lucas connector because it's the Workshop manual 'modification' instructions for aftermarket use at a Dealer Workshop.
Aftermarket fitment of the heaters was most likely to be carried out on a Pull Switch car, which have screw terminals.
Only the latter Flick Switches have spade terminals, and I'm guessing most if not all of them left the factory with a heater of some type.

Yes I thought that too but these are instructions for the late heater. I thought flick switches were in use by then?

Yes, but as I said, the most likely customer for have a heater fitted would be one who didn't have a heater, and they were more likely to be an earlier car.
New Switches were introduced in 1964 as was a standard fit 2.8Kw heater, with the option for a 3.8Kw.
These were both Rectangular heaters, not the earlier round one.
The round one is seen as the SII/S3 Heater.
So the instructions in the manual are unlikely to be used on a Flick Switch car.
Always an exception to the rule of course, knowing the way these cars were built, it's unlikely that all changes came in on the same day; that would be too easy....

[svenedin]

Interesting. I did not know there were 2.8Kw and 3.8Kw variants of the rectangular heater. I wonder whether they used the same case but a bigger matrix inside or if they were different externally? There isn't much room in the standard heater case for a bigger matrix. Charles Ware did offer a different matrix for the standard heater that had bigger input and output pipes and so was claimed to have a higher output but of course it had to be plumbed in to the standard flow and return fittings so whether it made any difference I have no idea.

Stephen

[geoberni]

Quite a bit different internally from their illustrations.
Oddly enough, though nothing really surprises me with Morris documentation, the 2 Radiators, as they were termed, did have different part numbers,
17H 8608 and 17H 8607.
Yes, you guessed, the 08 is the 2.8Kw, while the 07 is the 3.8Kw... As though they developed the smaller heater afterwards....

Difference in motor arrangement too. Plate P4 is the 2.8, Plate P6 is the 3.8.
.

Rectangular heater.JPG (74.43 KiB) Viewed 1189 times

[svenedin]

Ah yes. I just looked it up as I now have a pdf copy of AKD3542.

The 3.8Kw heater is the type with a separate blower. The heater box in the car is similar to the late 2.8Kw Smiths rectangular type but it has a bigger matrix so there is no room for the fan and motor. The blower is mounted at the front of the car near the radiator as seen on page 93 of Ray Newell's book "The Original Morris Minor". Mr Newell calls the unit a "heater booster" but really it is a separate blower. This was for Scandinavian markets.

Stephen