|
|
Post by tommydp on Sept 29, 2013 22:08:02 GMT
Hi all!
It's getting colder..
"By accident" i stopped the white one today while the heater/ fan was still running. This reminded me of something I've never figured out, as it happened to the blue one too.
If you stop a polarity converted car while the heater is running, the engine will run on! That is, if you've not switched the wires going to the fan. The "green circuit" plays up the "white" ignition circuit I suppose. (I'm no expert on electrics..)
I did a test on a heater motor once, and it is in deed polarity sensitive, ie if you switch the polarity and leave the heater wiring as is, the heater will run slower and make the engine run on when you stop it.
If you switch the wires (green ignition fed and black earth) going in to the heater, it will go faster when negative earthed. REMEMBER: YOU HAVE TO FIT ANOTHER SWITH RATHER THAN OPERATING THE FAN BY THE SCREEN/ CAR LEVER AND ISOLATE THE WIRES AT THIS LEVER, BELOW THE ASHTRAY. I found out the hard way once,when I switched the wires on the blue one, as the wires started burning...
Well, what I'm wondering is: will the condition have any effect on the ignition circuit while driving,heater on or off, or is it only making it run on when you stop? Just curious, and will get into switching the wires on the white one too. Of course you want the fan to go as fast as possible, and I would no doubt switch it, if it plays up the ignition in some way. Not that I've noticed anything, on the white that is..
Tommy
|
|
|
|
Post by Penguin45 on Oct 3, 2013 23:39:25 GMT
Tommy, that doesn't make any sense at all! I assume that you reversed the wiring at the motor when you did the polarity swap? That should ensure that the motor still runs the "right" way.
Really, I think you need to have a look at the fusebox/housing (I know, you sent me the good spare one......). The motor shouldn't run with the ignition off, so it has to be a switched supply - something is wrong in the wiring around the fusebox.
Chris.
|
|
|
|
Post by tommydp on Oct 5, 2013 8:32:01 GMT
The car was converted to negative earth in the 80s, by the previous owner. The heater motor wiring has not been reversed, so it's running the wrong way I guess. At least the heater in my blue one, which I eventually switched the heater wires on, runs much faster. I suppose this effect.
To be honest, I used to be of the opinion that a clock, radio and some gauges would be the only things that would need attention during a polarity change.
Don't remember the details, but I think there is one connection at the top of the heater, where two wires enter. A green(current supply) and a black (earth) wire. In addition to reversing them, you also have to switch the wires on the heater lever panel, or isolate them and install a switch for the heater.
Forgot something?
Tommy
|
|
|
|
Post by dave1800 on Oct 5, 2013 13:31:38 GMT
Tommy The only way to sort this out is to disconnect the blower motor leads and check that neither of them is shorted to the case ie grounded. If one lead is grounded you have the choice of taking the motor out and finding the problem or ensuring this lead is only connected to ground. If the blower is OK, then check the switch actuated by the heater lever. If this switches to ground by any chance and I don't think it should then put this in line with the negative connection to the motor otherwise switch the positive. The positive lead should be connected to a live that is switched by the ignition. I imagine that your engine runs on because you have a live wire feeding power to the coil via the blower motor. With something as simple as the blower I would find it easier and much quicker to rewire making sure you get a good ground and power connection. It should run just the same speed in reverse as forwards. I don't recall having this problem when I converted my Mk1 to negative earth, but it was 40 years ago! regards David The car was converted to negative earth in the 80s, by the previous owner. The heater motor wiring has not been reversed, so it's running the wrong way I guess. At least the heater in my blue one, which I eventually switched the heater wires on, runs much faster. I suppose this effect. To be honest, I used to be of the opinion that a clock, radio and some gauges would be the only things that would need attention during a polarity change. Don't remember the details, but I think there is one connection at the top of the heater, where two wires enter. A green(current supply) and a black (earth) wire. In addition to reversing them, you also have to switch the wires on the heater lever panel, or isolate them and install a switch for the heater. Forgot something? Tommy |
|
|
|
Post by tommydp on Oct 5, 2013 18:59:51 GMT
Had a look at it. Ok, it does not go faster but blows more air when it runs the correct way, as far as I can tell.
I reversed the black and green wires going into the heater motor. There are also two wires at the lever swith. One is grounded by the lever (black). Connecting these two wires starts the heater motor. I connected these two wires to a separate switch which now starts the motor.
Well, it sure blows more air now. I have not tested if the engine still runs on for a few seconds when i turn the ignition off while the heater motor is blowing.
If it does, is this really a problem? Does it play up the ignition circuit? Perhaps it's what makes coils warm? LOL...
T
|
|
|
|
Post by dave1800 on Oct 6, 2013 2:10:20 GMT
If it does cause the engine to run on then take the power feed for the blower motor from another source. I really cannot understand how it possibly could but never completely discount anything where car electrics are concerned, they seem to defy all the laws of physics! Guess it could account for your hot coils but only when you have it on full heat  Regards David PS have you never spotted any brake G problems that would show up on slippery surfaces over there? Well, it sure blows more air now. I have not tested if the engine still runs on for a few seconds when i turn the ignition off while the heater motor is blowing. If it does, is this really a problem? Does it play up the ignition circuit? Perhaps it's what makes coils warm? LOL... T |
|
|
|
Post by Penguin45 on Oct 6, 2013 11:18:42 GMT
Getting the motor running the right way will certainly make the fan more efficient, even if it's running at the same speed. It's a centrifugal type fan, which is actually quite efficient, but will only move about 30% of the air it could move when running in reverse.
I'll have a read through the wiring diagram later and see where the circuits are meant to be routed.
Chris.
|
|
|
|
Post by dave1800 on Oct 6, 2013 12:07:49 GMT
Tommy, I forget, did you ever sort out your hot coil? If not you could try a coil with 1.5 ohm primary resistance (sometimes sold as a 6V coil) with a matched 1.5 ohm ballast resistor in series, bypassing the resistor only when cranking making starting easier especially in cold weather by temporarily over-driving the coil. This has the effect of reducing the heat in the coil. Assuming battery voltage = 12V (it's closer to 13.8v when running) (a) the standard coil has a resistance R of around 3 ohms so the current I = 4 amps (V/R = I) (b) ballasted coil resistance 1.5 ohms, ballast resistor 1.5 ohms, current I = 4 amps (V/R = I) heat generated Watts = IxIxR (current squared x resistance) (a) std coil = 4x4x3 = 48 watts x dwell 60% = 28.8 watts (b) ballast coil = 4x4x1.5 = 24 watts x dwll 60% = 14.4 watts (the other 14.4 watts is dissipated in the ballast resistor) Another advantage of the ballasted coil is that it is lower inductance and so the back emf (voltage) is considerably lower and this is MUCH kinder to electronic ignition systems. David Perhaps it's what makes coils warm?. T |
|
|
|
Post by tommydp on Oct 6, 2013 17:25:57 GMT
Thanks Dave! I never really got to the bottom of it. The blue one has been standing for over a year now, and I'm planning to get into it during the winter, as I now have a well functioning one to compare everything with. The white one has now been my daily transport since April, with very few problems!
Looking back, perhaps the hot coil was not a problem, as the white car's coil will also get hot after idling for a time. It runs beautifully however. I'm more to the theory that I never got the carburettor settings right.
Regarding the running on when heater runs, it actually still does it after I fitted a separate switch and reversed the wires (I can tell for sure it's running the correct way now. I checked the blue one today too, and the same thing still happens to that one! Strange!
I'll look into the green wires. At least the heater motor, the brake lights and possibly the wipers and indicators are fed from a connection at the voltage stabilizer relay behind the speedo. I'll get into the wiring diagrams again, and possibly arrange everything similiar to mk 3 cars.
Also, in the dark, I notice the charging light glows dimly when operating heater or brake lights, but not when switcing on head lamps etc. BTW everything electrical works.
Could this be a problem to the ignition circuit, or is it just an annoying? thing to live with?
I WOULD APPRECIATE IF SOMEONE ELSE COULD TRY TO STOP THEIR ENGINE WHILE THE HEATER MOTOR IS RUNNING, TO SEE IF THEIR ENGINE RUNS ON FOR A FEW SECONDS, TOO.
By the way, Dave, I've never had any issues with the G valve or brakes in general. And on slippery surface the 1800 feels very safe and stable to brake. I've not yet tried an emergency brake, but will. I always watch the large brake gauge on the wall when I take it to the bi annual Norwegian MOT, which includes rolling brake test. They first do the front brakes, then the rear ones and finally the handbrake. I always get compliments for the brakes being very good for an old car, on any 1800. As long as the rear brakes are correctly adjusted, the 2 hands on the gauge are always dead even between left and right brakes. I can't recall, but I think I've only seen the rear ones lock when they do the hand brake. I'll check next time.
Regards, T
|
|
|
|
Post by Penguin45 on Oct 6, 2013 21:09:28 GMT
Well, mine stopped just fine.
Fan circuit does run from the voltage stabiliser, which is fed from A4 on the fuse box. Ignition circuit is an un-fused circuit, therefore the only common point of contact is the earth. The theory, logically, cannot be true.
Chris.
|
|
|
|
Post by dave1800 on Oct 7, 2013 2:13:56 GMT
As Chris says, this defies all logic! You have three options: a) ignore it b) check every earth point resistance measure to battery negative (neg earth!) c) disconnect each component (lights wipers radio etc in turn until you find he offending item Worth checking you don't have any leakage current when the engine, lights etc off apart from clock and alternator (very minor). Probably caused by a Norwegian Elf I hear they can be troublesome (see workshop manual section L6) David Regarding the running on when heater runs, it actually still does it after I fitted a separate switch and reversed the wires (I can tell for sure it's running the correct way now. I checked the blue one today too, and the same thing still happens to that one! Strange! Also, in the dark, I notice the charging light glows dimly when operating heater or brake lights, but not when switcing on head lamps etc. BTW everything electrical works. Could this be a problem to the ignition circuit, or is it just an annoying? thing to live with? I WOULD APPRECIATE IF SOMEONE ELSE COULD TRY TO STOP THEIR ENGINE WHILE THE HEATER MOTOR IS RUNNING, TO SEE IF THEIR ENGINE RUNS ON FOR A FEW SECONDS, TOO. Regards, T |
|
|
|
Post by tommydp on Oct 7, 2013 8:04:56 GMT
Thank you, Chris and Dave!
Could be an elf, of course, or the old barn I'm working in is haunted:-) That wouldn't have come as a surprise at all..
Well, on the other hand, I'm happy to post a video if you don't believe me:-) And it happens to both cars..
I'm afraid living with it is no option, as I'm not that kind of person:-) I'll check and clean all earth points and disconnect various green wires to wipers, indicators, brake lights etc to see if this stops the running on. I'll also have a look at a spare heater, to see how it is wired. I don't see how the green and black wires, going into the top of it are connected to the black and green ones going to the switch lever.
I'm also sure this problem accounted for the strange behaviour I had with an electric oil pressure gauge, which I connected to a green (ignition switched fused) wire. The gauge showed more when the heater was on, and dipped when I used the brake lights or indicators.. I solved it by putting in a mechanical gauge...
I'll do some googling too. I remember reading about an MGB which would run on for a few secs when the brake lights were on.
Regards, T
|
|
|
|
Post by dave1800 on Oct 7, 2013 9:42:55 GMT
Very strange! I don't suppose the Norwegian cars were fitted with an anti-run on device like later US? MGBs? The electric oil pressure gauge dipping when applying the brakes is typical of a poor connection or just taking too much current for the wire. You may notice similar issues with indicators slowing down when you apply the brakes. It almost sounds as though your heater back EMF from the motor is adding volts through a high resistance connection. Try measuring voltage drops between the battery +ve and both sides of the ignition switch with various switched loads. regards David T I'm also sure this problem accounted for the strange behaviour I had with an electric oil pressure gauge, which I connected to a green (ignition switched fused) wire. The gauge showed more when the heater was on, and dipped when I used the brake lights or indicators.. I solved it by putting in a mechanical gauge... I'll do some googling too. I remember reading about an MGB which would run on for a few secs when the brake lights were on. Regards, T |
|
|
|
Post by tommydp on Oct 7, 2013 15:45:00 GMT
Hi again! No anti run on device or anything..
I've done some research, on a spare heater/ fan assembly. Here are the results:
Two wires enter the assembly, on top rh side. One black which goes to earthing point behind the dash. The other, green, is supply, from which comes from fuse A3 A4, via the voltage stabiliser.
The black runs straight through the assembly, to the lever switch. The green goes into the motor and out of the motor comes a green/yellow. This one goes to the lever switch too. So, current enters motor via green wire, runs out of motor to switch via green/ yellow wire, then when switch is on the current goes via the switch and black wire to the earth point.
Interesting bit was, the spare motor ran the correct way when connected to a battery, also when reversing the wires (+- earth). The direction of the motor is marked with an arrow...
I actually pulled the whole damn thing into the car and connected it to the car's green supply and black earth wires. It ran the correct way, and the car did not run on when stopping while this spare heater motor was running, by the car's wires.
So, conclusion I guess, the fault is in the heater motor. FUnny it has happened to both my cars then..
Regards, T
|
|
|
|
Post by tommydp on Oct 7, 2013 19:51:56 GMT
|
|
