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Radiator fan not coming on. I assumed this was the fan switch. I replaced it today with an 85C Wahler. This had no effect and now I'm confused. My brother tested the relays a couple weeks ago, I checked the fuses, that all seemed good so I ordered a switch. Oh and the fans spin too, on both speeds when directly powered.
It's getting warmer out and it's becoming a greater concern. With an ambient temp of 70 the car is running over the first thick white line. I really don't know how far is safe on these.
The radiator fan switch is a good place to start checking, there are three pins on the plug connector. One is a ground (as I recall) and the other two are switched to ground to activate the fan, low and high speed.
Unplug the radiator fan temp switch plug on the the radiator
Make a short jumper wire out of some 10-14 gauge wire
Plug the jumper between two of the holes in the plug (there are three) until the fan comes on. (I forget which holes but you can figure this out easy).
When the fan comes on, try swapping one end of the wire out into the other hole until you get the second speed working.
You should be able to have two speeds (low and high and you will be able to tell the difference as high is like hurricane force).
If jumping the radiator fan switch works fine..then either the engine temps are normal..or the fan switch is not working correctly..or..there is enough junk in the radiator that is keeping the hot coolant away from the switch so it will not operate normally.
Be sure the cooling system is properly bled too..air in the system will cause problems.
You and I must be alter egos in mirror universes: my fan just started staying on out of nowhere, even with ignition on but the engine not even cranked over.
Brad I'd almost say I'd take your problem, caus if this motor overheats I'll never find a car deal this good again. I have some info for you I'll drop that on your proper post.
Rusty, I remember having an air pocket issue in the 85 Jetta I had, what a pain to refill the cooling system. This is basically the same, even the same switch I had to replace. Forgot how similar this motor is even to the diesel. With what was on the old sensor junk in the radiator is possible, however I must go back to something you said-
"...either the engine temp are normal"
So, I've been reading through this enormous service manual, learning how every sensor works. One thing I can't find is what is normal ON THE GAUGE. Where should my gauge sit? When does the low speed fan kick on? If you're saying no fan is NORMAL then perhaps the motor just isn't getting hot enough to need a fan.
As to where your temp gauge should be running normally..I'm not sure what model Audi and engine you have..but the point is the temperature senders can vary in quality. As they get older they become sluggish..even the OEM part. So on our older Audi cars the gauge can become less reliable.
Usually the temp gauge reads low ..or the temp sender is out of calibration.
The gauge clusters can become erratic too. Usually the mounting points on the temp gauge need cleaning or if your temp and fuel gauges are wonky..you may need a new voltage regulator in the instrument cluster.
Geez that B4 cluster looks like it would fit in my B3....
I did note the volt-reg I was looking over the spare cluster I have last night. Unfortunately they both have busted speedo's so I'm going to fix the one that's out before I swap it in.
My temp/fuel gauges do work well, I changed the Temp Sender the same time as the Rad Fan switch. This may be why the temps seem to climb higher. I used a Vemo it was the only one I found available.
That test is awesome, and hilarious. So now I'm going to go start the car, and just wait for the fan to come on. Maybe I have no real problem at all.
Something I learned in a video last night... caught a glimpse of these gauges on a Euro-spec dash. It actually has the degrees on the gauge (what a concept) the first thick white line is 80C, and the second (only other) thick white line is 120. So that's a handy reference when a sender is properly calibrated.
I have a 1988 80 with the 2.0. Hopefully my Sig shows that now, sorry.
Okay, 90C. I was close, video was fuzzy.
So if that's the case, my low speed isn't working. The car hasn't gotten to the point where the high speed would come on.
Does the sender link straight to the gauge, or go to the ECU first? I noticed as I was going thru the wash tunnel today (I didn't have the patience to sit in my driveway and wait for a fan) when the temp gauge hit dead center my high idle finally dropped to 1000 and stayed there.
You have a temp sender I and temp sender II..The blue one gives information to the ECU..it looks just like the other..which is usually black..and maybe a green stripe on it..that one is for the temp gauge...If your engine looks like this:
Oh that's right... totally forgot about that one jammed against everything on the bottom of my water neck. I have brass senders. They are quite similar but my top (gauge) sender has a boot-type connector. 1 pin goes to the gauge and the other goes to the "you just ruined your motor" warning light. It seems most of the cars had the larger 4-pin connector as I was only able to find one 5cyl coupe quattro in the yard that i could grab a new boot-connector from. I don't get why since I have A/C and the other pins on the 4-pin are A/C related. Which, I believe, would tie in to kicking my fan up as well.
04-03-2017, 01:49 PM
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