Author Topic: Rad Fan help... (Read 6700 times)

TD_Bunny · « **on:** March 20, 2009, 08:34:11 pm »

Just got my 1.7L timed and running which is sounding great so far (thanks Caveman)! Now i am dealing with small issues i did not know about the car i put the engine in...

My radiator fan is not kicking in. I am sure i have the fan wiring correct (Scirroco Flex-a-lite 365 dual fan) with solid brown ground and stripped hot. In my 2dr i was able to get the rad fan to kick on at least when i switched to AC on my controls and turned it on to low or any speed. But on this new project that does not turn the fan on. I checked the small 30A fuse and it was okay. I am going to check the radiator fan relay next to see if it is bad (the large box like fuse near fusebox). I let the temp climb to 2 white notches before the red before turning off the engine. If it has any relation when it comes to circuitry my clock or radio do not work either. I am not sure if the upshift light works yet (any way to test).

Any help would be appreciated so i can get to road testing my new TD

AudiVWguy · « **Reply #1 on:** March 20, 2009, 10:58:10 pm »

Start by putting power to the fan, after checking that, plug it back in and jumper the plug to the thermo-switch. If the fan runs, then the thermo switch could be bad--test it. If still nothing, go to the relay. Basically the wire that goes out of the relay goes to the thermo-switch and back to the relay. When it gets hot enough, the switch closes and power is relayed to the fan. The relay transfers power to the fan.
Maybe someone else can explain it better.

TD_Bunny · « **Reply #2 on:** March 21, 2009, 12:00:15 am »

i understand conceptually what you mean AudiVWguy but i do not know which thermo-switch you are talking about. I dont have a fan plug anymore since i had to splice into the new fan setup. Is the thermo switch the one that comes out of the driver side of the head or is it the switch with two plugs coming out in front of the #4 cylinder facing the radiator (1-2-3-4?)? If the switch is the latter then i have a couple of spares i can try out.

burn_your_money · « **Reply #3 on:** March 21, 2009, 05:11:21 am »

The thermo switch is the one built into the rad, usually at the bottom of the rad on the drivers side. If you have AC it should be a 3 prong (for dual speed fans)

the caveman · « **Reply #4 on:** March 21, 2009, 06:44:11 am »

Hey i'm glad it's up and running !!
After reading your -post and since it's not an oem fan, i think you're going to have to explain in more detail what you have done to the fan circuit wiring, maybe some pics and maybe a link or scan or the wiring for that aftermarket fan. It should be very simple- a constant 12v supply to either the fan or rad fan switch [the one on the radiator, either 2 or 3 wires] and a way to trigger the fan to come on
. The way the factory one is this- battery 12v to the rad switch. Then the output of the switch [when it gets hot] goes to the fan which is grounded and voila fan goes on. Don't know if that's the way yours is set up so we need more info.
You also need to share pics of the project [just because !].I wanna see that nice rebuilt engine.

TD_Bunny · « **Reply #5 on:** March 21, 2009, 07:55:27 am »

Here (http://www.flex-a-lite.com/auto/html/scirocco-fan.html) is a link to the fan i am using. It has two positive and two negative wires that come out for each fan. The radiator/Fan assembly was pulled out of my 83 so unless the thermo switch just decided to go south on me it should still be okay. Ill check the plug for corrosion to see if it is not getting a good connection. Next up is running through with a Voltmeter to check for grounding issues or no power.

Unfortunately with work i wont have a chance to dig in until next friday but ill collect any advice here and put it all to used when i have the chance.

@Caveman, yep thanks again the engine sounds great. Ill get some pics up when i can but i could kick myself now that i did not repaint it before getting it all in lol. O well still looks clean. Once i get the fan issue fixed i can get the exhaust finished as right now it pretty loud having the 2.25in TT DP being dumped just pass the firewall

thanks again guys for the help

jtanguay · « **Reply #6 on:** March 21, 2009, 08:00:38 pm »

how much does that fan kit cost? i've wanted a twin fan setup for a while now. that single fan just doesn't cut it. (big, bulky, and failure prone)

Vincent Waldon · « **Reply #7 on:** March 21, 2009, 08:32:36 pm »

Probably the easiest way to troubleshoot is to start at the top:

1) pull the connector to the thermo fan switch located on the driver's side of the radiator, near the bottom of the rad.

2) use a test light or multimeter to confirm you have power at the red wire. If there's no voltage your problem is upstream, probably fuseblock-related or the fuse itself (fuse #1)

3) use a short piece of wire to jumper between the red and red/white wire. The fan(s) should come on at low speed. If not, there's likely a problem with the fan(s) or the big resistor used to provide low speed (low speed bypasses the relay).

4) if they do, now jumper between the red and red/black wire. The fan(s) should come on at high speed. If they don't, there's likely a problem with the relay or the fan(s) themselves.

TD_Bunny · « **Reply #8 on:** March 22, 2009, 01:23:32 am »

@jtanguay
I got the fan kit from Jegs for 200. it works great and quickly drops the temps without a sweat. Its also not bad on the power draw when it kicks on.

Some updates, i did not think i would have time to do anything after work but i headed on over to where the car is tonight and started to check the recommendations i got here.

Vincent, i wish the new car had the wiring for the high and low speed like my 83 TD rabbit but it only has one wire other than ground on the plug. I jumped the two wires and the fans kicked on which i was very pleased to see. So, from what i am gathering from all of the posts, if the fans are kicking on when the wires are jumped then it has something to do with the thermo switch? Last time i was working on it i had the switch from my two speed setup and thinking that was possibly causing the problem since my other car is only a single speed i placed in the one speed switch. If that should not have mattered then does the engine really have to get that hot for the fans to kick on? It just seems like going all of the way to red is way too late to kick the fans on. If the different switch would matter then I may just need to get a new thermo 1 speed switch.

Can anyone else confirm if their rad fan comes on with you kick on ac or heat? mine used to in the 83 but it wont in this car. my TD rabbit was an LS and this diesel i put the engine is only a L model so maybe i am confusing additional options the LS gets?

Couple other items since i am in the troubleshoot section anyways

what is the best way to get to the airway from the center two vents to the blower? I wasnt getting any air out of the vents when turned on and lo and behold a freaking Pack Rat made a nest in there! Found this out after reaching down in from the engine compartment only to find stuffing lol. Well, i have all of the airways cleared now except the center two vents but i am not sure how to unplug them. suggestions?

Lastly, on the more technical side, I am having difficult getting power to the AC unit. When i kick on the switch I dont get any volts to the plug for the AC compressor so unless their is more than one plug that can go in what could i check for that? All small fuses are good in the fusebox.

Man i am making my car sound like a wreck! My reason for using it instead of the Orig TD rabbit though is because this one only had 75k Miles on it with all interior still in great shape. I got for free from a guy who had overheated the engine and did not want it anymore. Ill get some pictures up to support my case

thanks a bunch guys with ideas on where to look for solutions any help on the other issues would be appreciated.

thanks

TD_Bunny · « **Reply #9 on:** March 22, 2009, 07:50:17 am »

well i had time to get a couple photo shots out so here is my car. will be sure to post many more in the general section soon. I will keep this thread to relevant pics if some are needed later to figure out my wire issues

TD_Bunny · « **Reply #10 on:** March 22, 2009, 08:47:59 am »

Okay so radiator related again. I was looking at ordering the rad thermo switch and noticed that the two pin is only for non-AC and I need to use the 3-pin for my AC. Okay, i dont mind splicing in my other plug from my extra rabbit but then where does the third wire go? Will my AC work without the 3-pin rad thermo switch? Also, I take it this is why the fan does not kick on when turn the AC switch on?

TD_Bunny · « **Reply #11 on:** March 23, 2009, 02:14:10 pm »

bump, still just curious to know if anyone has an AC diesel with only a 1 speed fan setup? In other words, should the fan still work in an AC car if the radiator thermo switch is only a two pin instead of a three?

jtanguay · « **Reply #12 on:** March 23, 2009, 02:30:16 pm »

Quote from: "TD_Bunny"

bump, still just curious to know if anyone has an AC diesel with only a 1 speed fan setup? In other words, should the fan still work in an AC car if the radiator thermo switch is only a two pin instead of a three?

i know a friend with an '85 audi 4000 with a 1 speed fan with a/c (my brother currently owns it now). the a/c is inoperative, but unsure if the fan kicks on with it. the fan blows really fast and cools the rad fairly quickly with just one speed though...

i would assume that the a/c does kick on the fan, but using a resistor to limit the speed/nrg consumption.

if your fan doesn't come on when its at the a/c setting, then most likely you have a blown resistor. they are fairly big and are enclosed in a cylindrical ceramic tube.

TD_Bunny · « **Reply #13 on:** March 23, 2009, 06:28:31 pm »

Quote from: "jtanguay"

Quote from: "TD_Bunny"
bump, still just curious to know if anyone has an AC diesel with only a 1 speed fan setup? In other words, should the fan still work in an AC car if the radiator thermo switch is only a two pin instead of a three?

i know a friend with an '85 audi 4000 with a 1 speed fan with a/c (my brother currently owns it now). the a/c is inoperative, but unsure if the fan kicks on with it. the fan blows really fast and cools the rad fairly quickly with just one speed though...

i would assume that the a/c does kick on the fan, but using a resistor to limit the speed/nrg consumption.

if your fan doesn't come on when its at the a/c setting, then most likely you have a blown resistor. they are fairly big and are enclosed in a cylindrical ceramic tube.

Where is the resistor located and is this an inline resistor that can be replaced? Oddly enough the AC issue is the same one i was having on my 83. I would flip the switch to AC, the radiator fans would kick on, but the AC compressor would not get any juice. I am going to spend most of this coming friday working on it so any other ideas would be great. I am also going to get a new thermo switch for the radiator fan temp issue just to be sure because if the fans come on when the wires are jumped then the switch either is bad or not I did not let it get hot enough.

Edit: is the resistor part of the AC control panel?

Possum79 · « **Reply #14 on:** March 24, 2009, 12:45:56 pm »

I have a 79 rabbit 1.5l na with single speed fan. My fan will turn on with my AC on. I dont think my rig is factory AC though. Seems too oakie to be factory. Im having a problem of getting real close to the red line with no cooling untill I turn on the AC or the heater to releive the heat. I just replaced the thermo switch not to long ago and still have the problem. My fan would kick on if I let it sit at idle for a long time and stay under the center on the gauge. If I drive it she gets real close the red line unless I turn the AC on. Its like my fan doesnt stay on long enough. I dont know if my random junk helps at all.