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MG Midget and Sprite Technical - heater blower

I've been reading about the MG midget 1500 heater blowers on the net and some say they work equally well in either direction but I was wondering if that can be true. I was checking the wiring because when 'correctly' wired it runs in reverse and very weakly blows into the engine compartment. With the wires reversed, the blower blows in the correct direction a little better but it's still no hurricane. Should I expect better performance or am I making a storm in a teacup for myself?

BTW, I wonder why the blower switch interrupts the live feed rather than the return to earth? I'm going to wrap the switch terminals with tape so they are not able to touch anything...
Nick Nakorn

I believe if you reverse that type of fan it doesn't suck, just blows less effectively (relatively speaking!)
I run without the fan and still get a fair old flow just through forward motion.
Graeme W

Graeme, when working in 'correct' wiring position the fan blows into the engine compartment, albeit weakly. I've since had the unit on the bench and put the motor in a vertical position; gave it a good spray of wd40 through it's cooling holes and ran it for a minute or so. I suspect it's an earlier motor that was wired for a positive earth car so in a negative earth car the colours of the wires are incorrect. I'll put it back into the car later and see if it blows better. With the engine running and a decent battery I expect it will do better than the bench test.
Nick Nakorn

Nick,
again a photo might help or a look at recent threads on this subject in the archives

sorry but if the fan isn't great on the bench then it won't improve when in situ, no doubt you've already cleaned the impeller/fan to reduce the weight the motor has to turn

my (negative earth) fan was/is wired correctly but the switch was wired backwards and as Graeme has put it still worked but not as effectively

the way to get more heat and/or air through the matrix and/or heater box is to have the body to heater box seal in good condition, same for matrix seal plus being positioned correctly otherwise you're losing heat and air for an unsealed box and passed the matrix rather than through it

you don't need to use the fan above 25mph as the rammed air from the air ducting pipe with the flap fully open is enough (there are certain Handbooks with this info) and I keep the air duct flap fully open all the time even during cold winter use as this gives me loads of hot air for the cabin with the heater tap fully open - tap/valve fully open, air duct flap fully open, fan off unless going below 25mph - I've done 6 full winters use with my Midget including the worst winter for decades so I've had practice
Nigel Atkins

This thread was discussed between 13/07/2014 and 14/07/2014

MG Midget and Sprite Technical index

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