chrishawley Posted June 10 Report Share Posted June 10 Spitfire 1500: It's only a little matter but the heater fan only works on 'fast'. Everything else is fine but not a sausage where the half-speed fan is concerned. An no continuity on the relevant wire coming out of the heater box. So it seems a reasonable assumption that the resistor has failed. But what is a suitable replacement? As I recall the resistor is about 2 - 2.5ohms and the motor (when static) is about 2 ohms: So that seems quiet a bit of wattage to be dumped as heat. Any suggestions on what could be used as a replacement would be much appreciated. TIA. Link to comment Share on other sites More sharing options...
SpitFire6 Posted June 11 Report Share Posted June 11 Hi, Wattage is no so important as it will have air blowing over it unless you externally mount it. Link to comment Share on other sites More sharing options...
Wagger Posted June 11 Report Share Posted June 11 I have yet to search, but you may find a Pulse Width Modulation controller for this. That would not waste heat in the controller. When I had loads of old electronic bits I could make these. Sadly, they are long gone. Link to comment Share on other sites More sharing options...
PeteH Posted June 11 Report Share Posted June 11 6 minutes ago, Wagger said: I have yet to search, but you may find a Pulse Width Modulation controller for this. That would not waste heat in the controller. When I had loads of old electronic bits I could make these. Sadly, they are long gone. Curious?. But might we talking about something similar, which allowed a crude but basic proportional rudder control of a radio controlled model boat in the late 50`s?. Basically in the off state the rudder was hard straboard, in the full on state it was hard port, at Equal on/off frequency the rudder was straight, any part movement had a different helm position. It used some recently "invented" Transistor type electronics and worked off 9V battery. Pete Link to comment Share on other sites More sharing options...
Wagger Posted June 11 Report Share Posted June 11 1 minute ago, PeteH said: Curious?. But might we talking about something similar, which allowed a crude but basic proportional rudder control of a radio controlled model boat in the late 50`s?. Basically in the off state the rudder was hard straboard, in the full on state it was hard port, at Equal on/off frequency the rudder was straight, any part movement had a different helm position. It used some recently "invented" Transistor type electronics and worked off 9V battery. Pete Exactly correct. I have just viewed a few options varying from £6 to £200. Most use these for controlling radiator fan speeds. 1 Link to comment Share on other sites More sharing options...
johny Posted June 11 Report Share Posted June 11 Going by this interesting article a 25w 2.5ohm wire wound resistor from ebay would be more than sufficient... Heater Motor and Fan (mgb-stuff.org.uk) Link to comment Share on other sites More sharing options...
Wagger Posted June 11 Report Share Posted June 11 That will do and give a fixed speed. Needs mounting where heat does not cause a problem. Morris Minors had a rheostat with a control knob. Could be an alternative. Link to comment Share on other sites More sharing options...
johny Posted June 12 Report Share Posted June 12 Yes recommendation is to bolt the resistor to the inside of the heater metal casing so its in the airflow👍 Link to comment Share on other sites More sharing options...
chrishawley Posted June 13 Author Report Share Posted June 13 Thank you for all the ideas. To have to remove and disassemble the heater for only for the sake of one fan speed seems quite a degree of effort: But given the car is largely unmodified I'd like to try and keep originality, or at least authenticity, where possible. I've been given an MGF fan resistor pack (image below). This gives 1.3Ω, 2.0Ω or 3.5Ω depending on which connections are chosen. Looks like it might be possible to unsolder it and use the relevant coils soldered in place inside the Spit's heater box. Seems logical but is there any potential flaw in this plan....? Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 13 Report Share Posted June 13 yes dont tell the car its from MG Ha! pete 1 Link to comment Share on other sites More sharing options...
Wagger Posted June 13 Report Share Posted June 13 This does have the advantage of warming the air before the engine is warm, but it will warm the air when you want cool air. YOU WILL HAVE TO USE FULL BLAST TO GET THAT. Link to comment Share on other sites More sharing options...
SpitFire6 Posted June 13 Report Share Posted June 13 (edited) Hi, If you want some electrical heat in the heater box & you can fit, add H4 Bulbs. Each H4 bulb will provide 115 watts of heat energy. Fit three and you have 345 Watts of heat! Cheers, Iain. Edited June 13 by SpitFire6 , Link to comment Share on other sites More sharing options...
Wagger Posted June 14 Report Share Posted June 14 1000 watts hardly copes in a car on a really cold morning. I was surprised just how powerful scandinavian car heaters were when we owned a Volvo. I reckon that was 5kw when the car warmed up. The warmest I ever felt in a car was in my Pal's Reliant with the engine cover removed sitting beside the exhaust manifold with the windows wide open. We were fault finding 'On the fly' aged 21. (O joy). Link to comment Share on other sites More sharing options...
Colin Lindsay Posted June 15 Report Share Posted June 15 17 hours ago, Wagger said: 1000 watts hardly copes in a car on a really cold morning. I was surprised just how powerful scandinavian car heaters were when we owned a Volvo. I reckon that was 5kw when the car warmed up. Our former SAAB and the current BMW have amazing heaters, real 'drive you out' thingies even on low settings. One of the reasons 'Er Indoors never liked the Herald, but now prefers the modern convertible. Link to comment Share on other sites More sharing options...
Morgana Posted Friday at 21:42 Report Share Posted Friday at 21:42 Driving to Edinburgh this new year I had to keep turning the heater on and off in bursts as it was so effective! Link to comment Share on other sites More sharing options...
Dick Twitchen Posted Saturday at 07:09 Report Share Posted Saturday at 07:09 Heater in a GT6 Mk1 an optional extra, and I have never needed to use it in twenty years except to aid cooling stuck in traffic enroute to another Classic Le Mans. Link to comment Share on other sites More sharing options...
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