heater switch

[IIA]

A few questions about the heater switch on the instrument panel / dash of a Series IIA made for the US market:

1. Mine has 5 terminals but only 3 wires. Is something missing? What are the 2 others for?

2. How do I remove the switch from the instrument panel? I don't see any way to unscrew it.

3. How do I test it?

[darbsclt]

A picture is worth 1000 words...

To the best of my knowledge, a couple different heaters were offered... Smiths & Kodiak (to name two). Each had different switches. Not to mention that these were "wear items" often replaced by PO's, without a thought for originality.

Why not take a pic of the switch... front (face nut & knob/toggle) and back (terminal connections)... so folks can see the switch you have issues with?

Cheers!

[LaneRover]

There is something telling me that the heater switch is the same as the headlight switch on some models. Thus, the extra blades on the back of the switch would be for the parking (side) lights. Maybe you could wire up a 2nd blower motor!

[SafeAirOne]

There is something telling me that the heater switch is the same as the headlight switch on some models.

It is, at least on the SIII. I think this may be the same on late IIAs, but don't quote me.

It's a very unique universal switch where, depending on which terminals you use, you can get power output on 1 circuit with the switch in the first "on" position or to that circuit PLUS another with the switch in the second "on" position (parking light circuit first and then both the parking AND headlight circuits next) OR, if using other terminals on the back of the switch, power output through one circuit ONLY or the other circuit ONLY (heater motor low OR heater motor high, but not at the same time).

[EDIT:] Ahh yes. This diagram, from www.autoelectricalspares.co.uk shows the electrical connectivity within the switch in all three switch positions:




So...It looks like power goes into terminal 1

In the headlight configuration parking lamps are on terminal 4, headlamps are on terminal 8.

In heater configuration, low is on terminal 6, high is on terminal 8.


And to answer the OP's question, you should just remove the thin nut that goes around the base of the switch ON THE OUTSIDE OF THE PANEL. some nuts are slotted for a special pin spanner, but a flat screwdriver and a little tapping will get it off. Some of them have just a regular old thin hex nut.

How do you test the switch? Just put an ohm meter on terminal 1 and use the diagram in the above link to check for continuity (a closed circuit/0 ohms) on the correct other terminals with the switch in the various positions shown in the diagram.

Alternatively, if you're one of those people who are fans of the test light probe thingy, you can supply 12 volts to terminal 1 and probe the other, appropriate terminals for voltage with the switch in various position as shown in the diagram.

[IIA]

Thanks. That diagram looks about right. But the nut is on pretty tight. Any idea where I can get that special spanner or what it's called?

[SafeAirOne]

Speaking personally, I wouldn't bother trying to find a special small pin spanner that'll work; I'd just get creative with something I already own.

Pin spanners (adjustable and fixed):

[stomper]

Do you own an angle grinder? They usually come with a pin spanner to change out the grinding wheels. See if that fits your application.

[SafeAirOne]

Do you own an angle grinder? They usually come with a pin spanner to change out the grinding wheels. See if that fits your application.

Definitely won't. Just needs to fit into the 2 small slots on either side of the little nut that holds the headlamp or heater switch onto the instrument panel. Those pics I posted were generic examples of what a pin spanner is.

It's not complicated. In fact, it's pretty easy. It's just a nut around the threaded shaft of the switch holding to the panel. If it were me, and there was enough room to grip the switch body behind the instrument panel with my hand, I'd just give it a little turn in the anti-clockwise direction to break the nut loose, then use a flat-bladed screwdriver to assist in taking the nut the rest of the way loose

or...


...put something between my flat-blade screwdriver and the slot in the nut so it doesn't get too dinged up and gently tap the screwdriver with my favorite hammer till the nut loosens in the anti-clockwise direction, as depicted in this handy little photo here: