Need to get home. Please help - page 2 - Troubleshooting - VWDiesel.net The IDI, TDI, and mTDI source.
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#15 by Rabbit TD on 25 Jun, 2009 18:37
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Do you have a/c and does it work? A/C system problems can affect the fan operation.
We still don't know what kind of car it is but if it's a bad or weak relay are they interchangable in the MK2's and later like the old Rabbits and Jettas MK1's are? -
#16 by jtanguay on 25 Jun, 2009 18:42
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Do you have a/c and does it work? A/C system problems can affect the fan operation.
good call on the a/c. they can actually cause the rad fan to quit working due to thermal load/stress. the only reason that the fan can continuously run with a/c is due to the resistor. even on low speed i dont think the fan would last long, as it was never designed for it, and thus the reason for adding the resistor.
also, an mk2 rad fan (and most others) working intermittently is a sign that it is slowly dying. dealer prices for the fan are outrageous, so junkyard ones are your best bet. if you have no intention of keeping the a/c, then get the fan from a car without a/c. you will know that you can trust that fan because theres a 99% chance that it will work, and work for a long time. i've never had an mk2 non a/c rad fan die on me, and i've had 2, and the one car i get with a/c, the motor blew. heck i even attribute it to having damaged the engine because it was overhauled, but they didn't even bother bringing the cooling system up to spec. very sloppy work IMO.
heres my rundown on what probably occurred - very hot day, a/c is on. rad fan always on, but kicking into high speed mode frequently to keep the a/c cool, or to keep the engine cool. eventually the fan will say no more, and quit functioning. the worst part is that vw never introduced a failsafe for rad fan failure. so the rad fan begins to fail. the a/c system was empty when i got it.. gee i wonder why? the thermoswitch was probably trying to turn the fan on high speed, but it wasn't responding, so the gas got too hot and pissed right out of the seals! next the engine temp was climbing, and so the a/c was cut (the only reason the compressor didn't get shot) and tried kicking the rad fan on, but no dice. this is where the beginning of the end occurs. by the time the driver realizes that the coolant gauge is way over to the red, its too late. one other thing i noticed after replacing the condensor with a new one, is that there was almost what looked to be a nest between the condensor and radiator. after cleaning that out, i noticed that the car ran cooler from the extra airflow. this could have been another reason for the frequent switching to high speed fan mode. -
#17 by rabbitman on 25 Jun, 2009 21:42
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Make sure you have water circulating through the little hose and into the top of the coolant tank.
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#18 by rallydiesel on 26 Jun, 2009 21:04
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I finally got rid of all my a/c wiring after I was having fan issues (the a/c was inoperative since I bought the car). It's so simple now, I love it! Tested the fan the other day by running the car hard until it got hot - fan cut in exactly when it was supposed to.
If you want to bypass the a/c circuit to prevent overheating and you know your fan works (by jumping the thermoswitch) and hopefully your thermoswitch works, do this:
-connect the red wire that normally goes to the relay directly to the red wire from the thermoswitch
-connect the red/white wire from the thermoswitch directly to the red/white wire from the fan
-connect the red/black wire from the thermoswitch directly to the red/black wire from the fan
-connect the brown wire from the fan to a ground or negative battery terminal
The red wire must go from the loom by the battery directly to the thermoswitch. Bypass the series resistor. Do not turn on your a/c if it's still got pressure or you will blow seals and possibly damage your compressor. -
#19 by Rabbit TD on 28 Jun, 2009 17:42
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Do you have a/c and does it work? A/C system problems can affect the fan operation.
good call on the a/c. they can actually cause the rad fan to quit working due to thermal load/stress. the only reason that the fan can continuously run with a/c is due to the resistor. even on low speed i dont think the fan would last long, as it was never designed for it, and thus the reason for adding the resistor.
also, an mk2 rad fan (and most others) working intermittently is a sign that it is slowly dying. dealer prices for the fan are outrageous, so junkyard ones are your best bet. if you have no intention of keeping the a/c, then get the fan from a car without a/c. you will know that you can trust that fan because theres a 99% chance that it will work, and work for a long time. i've never had an mk2 non a/c rad fan die on me, and i've had 2, and the one car i get with a/c, the motor blew. heck i even attribute it to having damaged the engine because it was overhauled, but they didn't even bother bringing the cooling system up to spec. very sloppy work IMO.
heres my rundown on what probably occurred - very hot day, a/c is on. rad fan always on, but kicking into high speed mode frequently to keep the a/c cool, or to keep the engine cool. eventually the fan will say no more, and quit functioning. the worst part is that vw never introduced a failsafe for rad fan failure. so the rad fan begins to fail. the a/c system was empty when i got it.. gee i wonder why? the thermoswitch was probably trying to turn the fan on high speed, but it wasn't responding, so the gas got too hot and pissed right out of the seals! next the engine temp was climbing, and so the a/c was cut (the only reason the compressor didn't get shot) and tried kicking the rad fan on, but no dice. this is where the beginning of the end occurs. by the time the driver realizes that the coolant gauge is way over to the red, its too late. one other thing i noticed after replacing the condensor with a new one, is that there was almost what looked to be a nest between the condensor and radiator. after cleaning that out, i noticed that the car ran cooler from the extra airflow. this could have been another reason for the frequent switching to high speed fan mode.
My Rabit had some aftermarket a/c system on it when I got it. I ended up taking all the stuff out under the hood but left the inside stuff alone and now when you turn it's switch on you have the fan on the engine anytime you want it or the blower from the aftermarket system too in the car with a different posiition, it worked out pretty good especialy in stop & go traffic on the highway, it's amazing how much you can cool it down with that switch.