What solution to clean sensors?

[BMWTurboDzl]

Anyone have suggestions on what sort of solution to clean the in-cabin temp sensors and the temp sensor which sits next to the evaporator coil?

I was thinking rubbing alcohol but then started to think distilled water. I don't want to damage the blub on the evap temp sensor. Maybe if it's cheap enough I just replace it.

 

[Jethro_Bob]

What issue are you trying to resolve?

If "nothing."

That is also the correct course of action.

 

[BMWTurboDzl]

What issue are you trying to resolve?

If "nothing."

That is also the correct course of action.

A perfectly functional climate control system isn't being fed the correct values.
No clogged heater core.
No failed heater control valve.,
No failed blend doors.
No codes.

Indy shop suggests that I probably have a lazy sensor and it would cost a lot of $$ to try to track it down. I was thinking perhaps one or more sensors have a film on it which is causing the odd behavior.

 

[pantygnome]

Can you get to the wiring of them? Usually sensors like that are just thermistors, so the resistance will change based on the temperature they are reading.

If you can find the expected values (Google) you can measure yours and see which (if any) are reading incorrectly.

Might also be able to read the data with an OBD reader, but if its a BMW Im guessing it requires more expensive computery.

 

[BMWTurboDzl]

Can you get to the wiring of them? Usually sensors like that are just thermistors, so the resistance will change based on the temperature they are reading.

If you can find the expected values (Google) you can measure yours and see which (if any) are reading incorrectly.

Might also be able to read the data with an OBD reader, but if its a BMW Im guessing it requires more expensive computery.

I have an OBD app (Protool) but I don't think it gives me that level of functionality.

As for sensors there are a few of them. I have access to two.

One is embedded in the control panel of the climate control system.

Here's the other which is the evap temp sensor. I'm thinking that over the years (9yrs) a film has developed on the bulb and is causing the system to run cooler than it should. Dirt combined with moisture would cake on and act as an insulator. It would only take me 5-10 mins to get to it.

 

[pantygnome]

I think I would try MAF or electrical contact spray cleaner. Not a lot, but blast the bulb end and hang the sensor upside down (like in the pic) to let it drip/dry off.

As for the one in the control panel (and any others), is there some sort of small grill opening in front of it? Or maybe a tube that runs from the panel to the actual sensor? My old (old old) i30 had an accordion looking tube from the knee panel to the sensor and the tube would apparently dry rot and crack, leading to the sensor not getting accurate air to take the temp from.

Quickly Googling made it sound like the temp data *might* be available via OBD scanner, so it might be worth a shot trying that.

 

[BMWTurboDzl]

I think I would try MAF or electrical contact spray cleaner. Not a lot, but blast the bulb end and hang the sensor upside down (like in the pic) to let it drip/dry off.

As for the one in the control panel (and any others), is there some sort of small grill opening in front of it? Or maybe a tube that runs from the panel to the actual sensor? My old (old old) i30 had an accordion looking tube from the knee panel to the sensor and the tube would apparently dry rot and crack, leading to the sensor not getting accurate air to take the temp from.

Quickly Googling made it sound like the temp data *might* be available via OBD scanner, so it might be worth a shot trying that.

There's one buried in the dash behind the front vents. (Item #5)

https://www.realoem.com/bmw/images/diag_6lrd.jpg

Here's the one on the faceplate of the climate control system. No grill on this model. Circled in red.

 

[Dave9]

It is doubtful that a grime/film on this type of temp sensor would make any difference, except in a rapidly changing temperature situation, it would lag behind a little bit, not enough to notice any problem in use. Not the same situation as a heated o2 or MAF sensor.

If there's a massive gunk buildup, I'd just try a dry paint brush and then rubbing alcohol or detergent water, or residue free electronics cleaner but I don't think getting it clean enough to eat off of is going to matter.

 

[BMWTurboDzl]

It is doubtful that a grime/film on this type of temp sensor would make any difference, except in a rapidly changing temperature situation, it would lag behind a little bit, not enough to notice any problem in use. Not the same situation as a heated o2 or MAF sensor.

If there's a massive gunk buildup, I'd just try a dry paint brush and then rubbing alcohol or detergent water, or residue free electronics cleaner but I don't think getting it clean enough to eat off of is going to matter.

Are you speaking of both or only one and if only one which?

 

[Dave9]

Both, assuming the 2nd one is also a two wire thermistor setup. Measure the resistance, warm it up, measure again.

 

[zzyzzx]

If you think a better ODBII reader would give you actual values from the sensor, use it as an excuse to buy a better OBDII reader. I would try to find someone online with the same car and a better OBDII reader to verify this before buying anything.

 

[Soft Cars]

CRC contact cleaner.

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