Temp Sensor - '91 Audi 100

Hi,
I just put in a new Multifunction Temp Sensor, the 3 terminal replacement made by Behr. After installing, the temperature gauge does not read any
higher than the second hash mark on the gauge by the "C" (cold). Obviously something still wrong. Anyone know what other problems may cause this? Do you think it could be a defective sensor? The heater puts out heat and there are no other obvious signs the temp is really that low so I'm inclined to think the problem lies in the sensor or the wiring. Prior to replacing the old sensor the temp gauge worked intermittently and the temp gauge always registered in the normal range.
Thanks, Steve
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Steve, You could get a probe thermometer, and carefully place it between the fins of the rad and read the temperature of the fluid flowing through - just make sure you don't block the fan blades. On that idea, does the fan turn on at all if the car is left idling for a while? Can you put your hand on the upper rad hose without discomfort? Does the Bentley Manual have a resistance range that you could use to get a couple of resistors from Radio Shack and test the ranges of the gauge? It is possible that, when the old sensor was removed, that the connectors were damaged (the rubber boot around the connector does a good job of pooling coolant, which corrodes the wires and connectors). Cheers! Steve Sears 1987 Audi 5kTQ 1980 Audi 5k 1962 and '64 Auto Union DKW Junior deLuxes (SPAM Blocker NOTE: Remove SHOES to reply)

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Hey Steve, Thanks for your valuable input. The lower hose is actually cold, and the upper hose is just warm, not hot. I take it this means a thermostat problem. Right?
Thanks, Steve

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Steve, No probs. Chances are your t-stat has failed. I'd still use a thermometer to check the temperature of the coolant. In my 1987 5ktq it's fairly easy to change the thermostat, just move the ps pump to the side. I'm not sure if it's a more involved job with the '91 100. Cheers! Steve Sears 1987 Audi 5kTQ 1980 Audi 5k 1962 and '64 Auto Union DKW Junior deLuxes (SPAM Blocker NOTE: Remove SHOES to reply)

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Yes I think that I had a defective switch/sensor once for an Audi 90 with the 5 cyl engine. The temperature read correctly, but it wanted to flash the coolant warning light at different times. One Expensive switch/sensor. lol I think I will pull some off of the junk cars at the yards to keep on hand.
later, dave (One out of many daves)

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