Radiator fan keeps switching on and off
#1
Three Wheelin'
Thread Starter
Radiator fan keeps switching on and off
Lately, my radiator fan will only run for about 5 - 7 seconds at a time, then stop for around 3 seconds, then start again. It still comes on at around the right temperature and stops completely when the temp is back down - it just won't run for long periods uninterrupted like it used to. Anyone run into this before? I haven't touched the cooling system lately.
#2
Rennlist Member
No idea. Other than perhaps the temp sensor is failing and reading are swinging wildly up and down in large blocks.
#5
Three Wheelin'
Thread Starter
Yes - it's always off because it's not working
Not lately. Mine are actually in a different location (in the battery tray behind the battery). The wiring has been in rough shape for a while, but I don't see how it would cause this frequent on/off behaviour. I'll take a look though.
Not lately. Mine are actually in a different location (in the battery tray behind the battery). The wiring has been in rough shape for a while, but I don't see how it would cause this frequent on/off behaviour. I'll take a look though.
#6
Rennlist Member
Not lately. Mine are actually in a different location (in the battery tray behind the battery). The wiring has been in rough shape for a while, but I don't see how it would cause this frequent on/off behaviour. I'll take a look though.[/QUOTE]
Resistance caused by deteriorating wire will cause problems, heat and current fluctuation
Resistance caused by deteriorating wire will cause problems, heat and current fluctuation
#7
Three Wheelin'
So is the Fan Running just on high? it is one of two things.. The 3 pole switch in the Radiator, or as stated above the fans... I Cut all my Resistor wires out of the race car and deleted the Resistor blocks.. Now my car does the same thing... only runs on "High" but it only runs after if come offf track...
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#8
Three Wheelin'
Thread Starter
So is the Fan Running just on high? it is one of two things.. The 3 pole switch in the Radiator, or as stated above the fans... I Cut all my Resistor wires out of the race car and deleted the Resistor blocks.. Now my car does the same thing... only runs on "High" but it only runs after if come offf track...
#9
Three Wheelin'
Yes that is exactly what is going on... The fan comes on high... Cools the RAD so fast it shuts off, When it shuts off because there is only one speed working. Under "Normal" conditions, the temperature would never get that high, The fans would come on normally on low and run there cycle and shut off.... With the low speed in-operable the fans come on high for a short time and then off... Residual heat transfers and they come on again... and so on.... Till it actually IS cool... For my track car I don,t care but I can see were this would be kinda annoying on the street..
#10
Drifting
It’s a bit of a process but I had replaced all four wires from the resistor block to the power distribution block on my 89 NA. Ok it was a **** show, but it works great now.
#11
Nordschleife Master
What GPA951s says makes sense, however before you get any deeper into fixing stuff first check that your fans are actually only operating on high speed. You can do this quite easily by disconnecting one terminal from each of the low speed resistors and seeing if your fans are still coming on as before. If they are then yes it’s your resistors (or more likely the wiring to them) that’s the problem.
#12
Burning Brakes
Forget all this. Short fan on-time is due to a bad radiator fan resistor.
Check and replace one or both fan resistors located under the rain cover next to the battery.
They should be about 7.5 ohms if they are good, they will have open resistance if they are bad.
Check and replace one or both fan resistors located under the rain cover next to the battery.
They should be about 7.5 ohms if they are good, they will have open resistance if they are bad.