Heater, A/C Controls total Rebuild

[Jcat]

Am totally rebuilding my 81 528i climate controls. And, am wicked happy with how easy this is and how well it has gone. (would not be attempting this if I didnt have a couple of these to practice on; removing the flat nuts from the plastic studs without breaking them requires enormous patience). I will be posting photos and steps taken as I get through the process. Peter apparently attempted it, but not sure how he made out in the end as his FAQ in incomplete. (I Hope he sees this post) Heres the deal... The rotary knobs for fan and temp usually seize up over time, thus the rebuild. The seizing occurs due to a hardening of the grease protecting the controls moving parts over time. QUESTION: Now that I have the controls all cleaned up, I need some advice on the appropriate grease to butter up the contacts and lube the surfaces of the plastic rotary knobs, etc. I dont want to use something that runs when the interior of the car gets hot from the outside temperatures here in Atlanta. Certainly, the grease should be clear since instrument lighting at 1.2w has to pass through it. Thoughts?

[Jcat]

[Mike W.]

I used white lithium grease when I rebuilt mine. It's a relatively light grease, meaning thin, and since the problem is too much friction/stiction, I wanted something light. It's possible, but I don't recall any problems with light transmission thru it. I think drip point is around 200-230+ so that shouldn't be a problem. I think I've seen some synthetic greases that are clear and shouldn't be too heavy, but I'm not sure which ones. I would not use something like a HD wheel bearing grease.

That reminds me, IIRC I rebuilt a couple of spares and I should try to sell them.

[Jcat]

Hey Mike... Thanks for your reply. I understand that dielectric grease is not good for contacts. But I cant seem to find a clear grease out there that is conductive or specifically used for electrical contacts. Are my search criteria proper? All Lithiums seem to be white. Some synthetics are clear, but they seem to be dielectric. Is dielectric no good for this application?

[Mike W.]

A quick search suggests dielectric grease isn't generally used as a lubricant in the conventional sense. But if synthetic, it might be.

Pricey, but here's a clear grease, though I don't know how thick it is or isn't, but you might be able to search thru Q and A. Weird, I can't seem to post a link. So lets try an image, from Amazon.

[Jcat]

How coincidental, Mike! I called the company earlier and was put on hold once I began to ask about the products properties. Had to hang up. Will try again tomorrow. Should it be a grease suitable for elec contacts? Any key questions to ask of them?

[Mike W.]

Should it be a grease suitable for elec contacts? Any key questions to ask of them?

It should be, grease is generally non conductive. Only question I might have is how thick is it. Intended application might answer that, for instance wheel bearings use a heavy duty grease. Disc brake wheel bearing grease even more so since it has higher heat to contend with.

[canada karl]

Try 00 Lubriplate.

[Jcat]

Hey Karl. Thanks for the suggestion. Have you used this in this application?

[canada karl]

I haven't used it for heater controls but it is a cream like grease that looks like it is unlikely to get sticky and dry out. Just my thoughts there may e synthetic grease available that would do as well.

[Jcat]

I just emailed Behr. I know... its a long shot, but I was able to give them the corresponding Behr part number for the complete assembly so this should improve my chances. Will report back soon.

[0257]

JCat, ever figure out the correct grease to use on the rotary fan switch? I’m deep into mine as well.

Also, I note that not all the contact pins are identical in mine. 7 are identical, have the contact knob in the center of the pin above the spring. But the 8th (I think it’s a/c fan position III) has the knob on one end of the top, not centered over the spring. That seems odd. Odder yet is that in the dealer parts book there are supposed to be 7 identical pins, part number 64 1 11 355 525. But there’s no part number spec’d for the 8th pin. It’s pretty beat up, and was going to replace it (I have a new 525 pin), but am worried I’m missing something.

Did you come across this anomaly while rebuilding your switch?