Auto heater interior sensor question
 

Hi all,

I have a 1980 930 with auto heat. The internal sensor between the sun visors (looks like a conical pen cap with some holes in it) has failed. It looks like they are not available new, NOS or S/H, so I want to try repairing mine by replacing the thermistor.

Q: Is anybody able to provide resistance measurements at a few different temperatures? I have searched the forums and can't find anyone who has posted this info, but apparently there are some Bentley manuals that have resistances for the various sensors?

Any help (especially resistance measurements!!) greatly appreciated!

Peter, Australia.

Sensor.
 

Hope this helps.

http://forums.pelicanparts.com/uploa...1375796008.jpg

Good luck,

pm me as needed.

Gerry

http://forums.pelicanparts.com/uploa...1375796129.jpg

Peter, I've tried to insert scans of the Bently, but not able to. I will try to send them in an email. Be very careful with the connector on the thermister, the connection in the center is very delicate and easily can be damaged. Make sure it is clean, possibly use an electronics cleaner, and it is making good contact. Any variance will affect the operation of the system. If you set it correctly it will function. If it is not or has an intermitant open then it will drive you crazy.

Sensor Specs.
 

CPA is right.

Be very gentle with the sensor.

Here are the specs:

http://forums.pelicanparts.com/uploa...1375817641.jpg


Good luuck,

Gerry

Thanks Gerry. Is the label you supplied for a part equivalent to the interior thermistor? If so - problem solved!

The Bentley table provides a resistance at 20C (which is fine for testing the thermistor is functional), but I really need another temperature point or two to be able to work out the resistance curve.

Regards, Peter.

Label
 

It is.

Hi Peter

Did you ever find a thermistor replacement for the interior sensor and if so, where and what were the specs and part number.

Brian

Y'know, it is really hard for that thermistor to fail. For mine, it ACTS like a failure when the connector becomes loose or disconnected. Happens when I put up the windshield protection screens -- sometimes I bump the conical sensor cover and knock the connector loose. it is NOT a great connector and bears watching.

In my autoheat setup, the cam attached to the rotating switch is broken off. Normally, when at "0" the thermistor is taken out of the loop. On mine, when the connection is broken, the autoheat thinks the sensor is open and turns on the heat full blast. That's when I pull over and get out the small phillips screwdriver and reconnect the thermistor.