Heater

[FEDUP]

Hi
Just about to install refurbed heater back into car, last check to make sure every thing ok.
Powered motor with direct fused 12v from battery fine no problem powered motor from lucas two speed resistor motor turns slow and not so slow. Question can i replace resistor with a modern one which allows different speed setting any advice welcome
regards ian

[gerrym]

Ian, the resistor only controls the motor speed at the SLOW setting. For the NOTSOSLOW setting, the motor sees the full voltage. Suggest you check again with the engine running, as 13.5V or so will give you some slight improvement compared to about 12V from a battery.
If you want to changeout the resistor for the a different setting, you could try one from just about any modern car (which still use them to obtain different blower speeds). Suggest you avoid modern fly by wire types though (generally last 5 years european).
Alternatively, logon to RS Components and purchase an aluminium housed wire wound resistor. This will need to be a large high watt device. Measure the existing voltage drop and resistance of your non preferred resistor. Calculate the required new value. Then calculate the heat dissipation of the new resistor to ensure the wattage rating is adequate (otherwise it will burn-out)

Regards
Gerry

[FEDUP]

hi Gerry.
Thanks will try again tonight but will also look at the rs site .
cheers Ian

[john.p.clegg]

Ian/Gerry
Other high street electronic retailers are available....maplin?

John

[rdssdi]

The original Lucas resistor is as previously stated for slow speed only. High speed is direct accessory power.

Make sure you wired it correctly.

Also try these people for resistors
http://www.thhs.co.uk/

They are Transport Heater and Hose.

Bob

[FEDUP]

Hi.
So if i understand this correctly i have direct power from switch to heater motor and the power to resistor for slow speed from other side of switch.
I have a black wire and a white wire from heater motor black direct to earth and white for live power feed .
From back of switch i have red/brown & green/yellow and on resistor i have 1 single terminal and 1 double terminal .
With this information what would be the the correct method to wire switch to resistor to motor .
regards ian

[tower of strength]

the double terminal goes to the blower motor and the full speed setting, the single terminal is the slow speed setting (not sure which wire colour is which though!)


Mark

[gerrym]

Ian, from wiring diagram for Plus 2 S130 (Non-Federal)

There should be a live feed from the Fuse Box (switched from ignition) through to the Heater Motor. The wiring diagram indicates that this is Yellow-Green. From the motor make the connections to the resistor. From the resistor there should be two wires through to the Heater switch. The Black -Yellow is the full speed circuit and the Black-Red should be the slow speed circuit. The switch then completes the circuit to earth.
Note this does not seem to be a common arrangement and may have been specific to the +2 S130 Non federal. Most of the other circuit diagrams (ie non S130) had the heater motor earthed with feed via the switch. Suggest you get your test lamp out to check which wires are live!!!
Gerry

[RotoFlexible]

If the motor runs well on direct power and not so well when fed through the switch (in "high" or "fast" position), it is time to look at your wiring. In theory, the fan should go as fast through the switch as it does on direct feed, but the motor is a significant draw, and the little resistances in the connectors, fuse contacts, switch contacts, and earth connection can add up to enough to turn "fast" into "not so slow."

As part of the renovation of my S2's electrical system, I put the heater fan on a relay to take the load off the switch. The relay is fed directly from the battery-alternator bus through a modern fuse. The difference is dramatic, as in, between "fast" and "not at all." In fairness, I lubed the motor bearings and cleaned out the accumulated leaves and junk, but the fan hadn't worked properly for decades - now it is fine.

[FEDUP]

Thanks for the advice all is well two wires to double terminal white /greenyellow on resistor.
Red/brown wire to single terminal i now have a two speed heater fast and slow many thanks ian

[jeff jackson]

Hi All,
FYI, I have just taken a few measurements: the Resistor ( Lucas 4BR) value is 3 ohms. The motor draws 3A with a regulated 12V supply, without the resistor in circuit.
When the resistor is in circuit, the current drawn by the motor and resistor is 1.9A. the volt drop across the resistor about 5.5V.
Therefore the power in the resistor is (1.9 x 1.9) x 3 = 10.83 Watts!
So if you are looking for a replacement resistor from RS, it would have to be a big one!
( just my two cents worth, first please, please, please do not use the terms Wattage and Amperage, this really winds me up, as there is no such thing. current is measured in Amperes, and power in Watts.)

Regards Jeff.

[gerrym]

Jeff, did you measure the current draw by the motor at operating voltage level?

Regarding term "wattage", IEEE clearly see place for this term in terms of ratings if not units of measurement. I quote

Developments in low wattage high intensity discharge lamps
Mucklejohn, S.A.; Preston, B.
Industry Applications Conference, 2000. Conference Record of the 2000 IEEE
Volume 5, Issue , 2000 Page(s):3326 - 3329 vol.5
Digital Object Identifier 10.1109/IAS.2000.882643

Regards
Gerry

[andyhodg]

Hi Guys

I have been following this with interest as I have a failed fan resitor on my +2. I have found an item at Maplin's that i think will help. It is a variable speed controller for 12 v dc motors. Max load 3 A. It should do the job nicely as a replacement for the resistor.

I'll let you know how it goes once fitted.

Regards

Andy