Sensors on coolant flange

[92EcoDiesel Jetta]

I know the top one is the temp sender for the coolant temp gauge. What is the side sensor? According to the parts list from a dealer, it could either be a thermal switch to switch off the A/C compressor, or a thermal switch to switch off the A/C compressor  and or elec fan. Which is it? I thought the elec fans are switched off by the 4 prong switch on the radiator (bottom drivers side).

[blackdogvan]

Mine tells the glowplugs to stay off when the engine is warm.

[92-Eco]

it is definately for the glow plugs, i just replaced my flange. when i got the car it had a single sensor flange on it with nothing hooked up. the flange i got had different ports than the stock one so i had to re-route all my coolant lines, not a big deal but you know. the other is for the temp guage. my car is so much better now that i have put this on there. i knew it wasnt overheating but its nice to have a guage that works and the glow plugs for sure make it start easier and quicker. i just recieved my manual for my car so it will be a little easier to work on, ive had to just track things down up to this point.

[92EcoDiesel Jetta]

What are the 2 sensors around the corner then? One is on the end of the cyl head, the other is on a plastic flange.

[Vincent Waldon]

Here's my opinion:

In your first picture you've circled the temp sensor for the temperature gauge and the thermo-cutout for the A/C that shuts off the A/C if the engine gets too hot, thus removing load from what is presumably an already overloaded engine.

In the second picture you've circled the low-pressure oil switch and the glow plug coolant temp sensor.

[92EcoDiesel Jetta]

Thanks Vince! I really need a Bently. I don't know what's wrong with Amazon, still no email that it has been shipped. It's overdue.

[rallydiesel]

Hmm, are you sure the one on the side is for the GP's? I was trying to find a replacement sensor/flange for the side of the head and found the flanges to be either: no sensor (non-a/c) or with sensor (a/c models) according to the parts catalogues I was searching.

[Vincent Waldon]

Hmm, are you sure the one on the side is for the GP's? I was trying to find a replacement sensor/flange for the side of the head and found the flanges to be either: no sensor (non-a/c) or with sensor (a/c models) according to the parts catalogues I was searching.

Well, you raise a good question.... 'cause you're right, there are A/C flanges and non-A/C flanges.

The challenge is the multiple configurations these cars came in....

On the cars I've seen, the A/C vs non-A/C flange was at the front of the head, and I know that the AC sensor is a switch as opposed to a thermistor (the sensor on the side of the head looks like the standard coolant temp thermistor to me) which was why I was thinking the A/C switch was at the front of the head.

OK, just checked ETKA and there's a wack of different configurations... on both flanges.

Here's how to tell the difference:  the sensors (temp gauge, glow plugs) have one or two wires (depending on if they're grounded thru the body or not) and the A/C switch has 4 wires.

Whew.   

[rallydiesel]

Just going over my Bentley and my car again.

My A/C switch connector has two wires. Both green.

The GP switch and the coolant temp sensor also have two wires (forget the colours).

I just replaced the side flange/sensor with a plain flange, no sensor style because it was leaking badly and I couldn't find another one with the sensor. I hope my GP circuit still works in case what I actually deleted was the GP temp sensor .

According to the Bentley, the A/C thermostat is an internally regulated switch and the GP and coolant temp sensors are both variable output senders.

Unfortunately all three have the exact same connector style so I could easily have mis-connected them. At least the coolant temp is fairly easy to troubleshoot but if I put it on the GP sensor it still could be way off if the sensors have different ranges.

[92EcoDiesel Jetta]

Just going over my Bentley and my car again.

My A/C switch connector has two wires. Both green.

The GP switch and the coolant temp sensor also have two wires (forget the colours).

I just replaced the side flange/sensor with a plain flange, no sensor style because it was leaking badly and I couldn't find another one with the sensor. I hope my GP circuit still works in case what I actually deleted was the GP temp sensor .

According to the Bentley, the A/C thermostat is an internally regulated switch and the GP and coolant temp sensors are both variable output senders.

Unfortunately all three have the exact same connector style so I could easily have mis-connected them. At least the coolant temp is fairly easy to troubleshoot but if I put it on the GP sensor it still could be way off if the sensors have different ranges.

The side flange with one sensor port (second pic above) is p/n 068.121.144 available from Germanautoparts.com . Sender on that flange has 4 terminals on mine. I still have to locate that sender on my Bently (which I just received in the mail). How many terminals are on yours?

Per my Bently on p 216, the connector that goes to the glow plug relay sender G27 has 2 wires (blue/white  and brown). On p217, the connector that goes to the coolant temp sender G2 is also 2 wires (yel/red and brown). Unfortunately, both senders uses the same connector style and they can be interchanged unknowingly. There's no p/n on my coolant temp sender so I'm not even sure if it's the correct one.

[rallydiesel]

The one on the side of the head on mine has two terminals and the plug to it has two wires (both green). The schematic is in the A/C section. I wish there was some way of identifying what flange sensor does what just by looking at it.