It should not be a problem. I hot-wired the aux fan on my 300SDL from Vegas to San Diego when the car overheat. There are a lot of aux fans from gasser in the JY, so do not worry about the life span of it for now.

You really need to measure the temperature of the engine and compare it to the gauge. You do not know what is going on without that info. It seems that the old sensor is giving a more 'realistic', not necessarily right, temp than the new one. I do not have my 300D with me as it was driven up to Santa Cruz on Monday, otherwise I could do some measurements for you.

I hope other members can supply you with some resistance value using their cars. I would expect any W123 uses the same sensor.

It seems that my SDL also uses the same sensor. I can give you a rough resistance measurement tonight at 85C and ambient temp.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.