James_Douglas Posted December 27, 2022 Report Share Posted December 27, 2022 Today it is raining hard here in San Francisco. I got up to take Sondra to work in the '47 and the left front tire is flat. Ok, so I say what the hell I will just take the '49 Convertible for its first drive in real rain. We get a block from the house and the wipers stop. Crap. She jump and runs for the bus in the rain. I get the car home, in the dark and in the rain and park it. I go do to the garage a couple of hours later. I start the car and turn on the wipers and they work and they keep working. WTF! I then turned on the headlights, which I had on in the dark and the wipers just keep working. I then turned on the heater fan which in a '49 is out by the radiator. After about 10 seconds the wipers stops working. I run off the heater fan and in about 10 second they start working again. I can repeat this over and over. The defroster fan which is under the dash, a separate motor, does not affect it. Nor does Turing on the radio. Now I did notice this last year that when I had the heat on that sometimes the AMP gauge needle would sometimes swing/spike. I am wondering what could be going on. Since this is a near concourse restoration with all the wiring new and every ground and then some in place, I do not think it is a ground problem. Is it possible that the heater fan is causing an intermittent electrical short to ground or something to screw up the power flow? A armature induced spike of some kind that the motor on the wiper or wiper controller is sensitive to? If anyone has any ideas I am all ears. I am going to see if I can hunt down a NOS motor and swap it out and see what happens. A real weird puzzle. James Quote Link to comment Share on other sites More sharing options...
Booger Posted December 27, 2022 Report Share Posted December 27, 2022 Voltage Reg? Tapping on cover would sometimes open points in wet weather Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted December 27, 2022 Author Report Share Posted December 27, 2022 9 minutes ago, Booger said: Voltage Reg? Tapping on cover would sometimes open points in wet weather I do not think so as everything else is working fine. No flicker on the headlights. This is only happening when the heater blower motor is running. I just ordered a NOS motor. We shall see... I turned on everything, including the cigar lighter, except the heater motor and the wipers work without stopping. I suspect an EMI problem. James 1 Quote Link to comment Share on other sites More sharing options...
Los_Control Posted December 27, 2022 Report Share Posted December 27, 2022 Just curious with your new wiring, do you have a fuse panel or circuit relays? Seems each item works ok individually .... except for volt spike on heater motor. When both wipers & heater turned on together you have a issue. So I wonder if they are tied in together & on the same circuit .... do they share a relay or a fuse? Meaning they are both on the same circuit. Relays can act funny, possible a wire is overloaded & overheating .... Just a idea of something to look at. Myself I would keep them separate & on individual circuits. Somehow they seem connected .... one affects the other ..... that does not seem right. Hope it is just a bad motor & fixes it. Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted December 27, 2022 Author Report Share Posted December 27, 2022 I have not confirmed it, but I think I know what is causing the failure. Why it is causing the failure is something I need to look into. In 1949 they started to use a lot of those little can circuit breakers. The ones that re-set when they cool off. The spike I noticed in the summer driving the convertible with the heat on, San Francisco fog remember, may have been the heater motor causing the breaker to open. I just read the 1949 service manual on causes of the wipers not working and the last item on the list was, "heater wired to circuit breaker". I ran down the schematic and it looks like if the heater blower causes that breaker to open, the wiper will stop with it, then when the breaker resets in about 10 second, it starts up again. I may need to pull the heater circuit wires off that breaker and connect those wires with a fuse so that the two circuits are isolated from each other. One can do without heat if it is raining in a pinch, but not with out the wipers. Hope fully a NOS heater motor will solve the problem. James 3 Quote Link to comment Share on other sites More sharing options...
DJ194950 Posted December 27, 2022 Report Share Posted December 27, 2022 (edited) My 50 would also trip the circuit breaker when lights , heater blower and defrost blowers were all on. Reset and on again for a minute or two then off again. Mine are all on 12 volt however with the heater/blower motors(2) changed to 12 volt replacements. The rheostat resistor type speed fan controls do still get quite hot when in use . I added relays for the high and low headlights which solved my problems. By the way on my 50 the wire diagrams show the cigar lighter is Not fused at all- What fun that can cause. I think the 49 and 50 wire schematics are the same.?. DJ Edited December 27, 2022 by DJ194950 Quote Link to comment Share on other sites More sharing options...
Go Fleiter Posted December 29, 2022 Report Share Posted December 29, 2022 (edited) The most valuable addition to my P23 is a voltmeter! You may attach it temporarly because of the originality of Your car. It may show You additional information to the Ammeter measurements. When adding high beam lights it shows if generator and regulator and battery still keep 6,5- 7 V. Freshly wired or not, check for loose connection! Than continue disconnecting one after the other electrical appliances. Good luck! Greetings from Düsseldorf! Go Edited December 29, 2022 by Go Fleiter 1 Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted January 5, 2023 Author Report Share Posted January 5, 2023 Well, I tried the easy way out and put in a NOS heater blower in the off chance that was it. It was not. Interesting that the replacement blower motor made by the same company as the factory original and having the same part number, but a difference sub number has a much larger ground wire gauge. Well. I looked hard at the manual and it tells you that wipers stopping can be because of having the heater or other wire connected to the wiper breaker. The 1949 Schematic does not show well the breakers and their wires. The 1950 shows it better and it appears that that used the two breakers not only as breakers but as power distribution points. If you put everything on the "protected" side of the breaker it will overload. hence the comment "e" in the service manual about troubleshooting the wipers. I will have to pull the heater-defroster wires off the protected side of the breaker and move it to the power feed side. I am going to make up a short wire that will plug inline with the heater motor and the defroster motor with an inline fuse in it. That will solve the problem and still provide protection to the wiring. So much fun. James Quote Link to comment Share on other sites More sharing options...
Marcel Backs Posted January 7, 2023 Report Share Posted January 7, 2023 If you have the room, adding a couple extra breakers to distribute the electrical loads and lowering current through each breaker would work wonders. Fusing the battery side of each breaker will help to protect that expensive wiring harness. The picture of the wiring above is indicative of why a problem exists. M Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.