Radiator Fan Switch Problems

1slowdsm · 10-14-2009

I've had my radiator fan connected from the radiator fan relay, on the passenger side, to a switch inside my car. Everytime I flick the switch my battery v would drop by about 2v, so it'll sit at 12.5ish then when I start driving it would jump up to 13.5ish. After a week or so I could see the drop go down to as low as 9v, which is about when my car would start losing battery power quickly. I've notice that my switch has been getting quite hot compared to what it was when I first added the switch.

NOW....the thing that bugs me is that every once in a while this would somewhat short out my battery - I would start driving and the car would just click on and off constantly for about 5seconds, then it would completely die. I would have to disconnect my battery, wait a bit and reconnect the battery and it would run fine again. This has happened twice to me since late August and I dont want to keep having to pull aside at any given time and disconnect the battery, it causes traffic and gets annoying.

Anyone have any ideas as to what's wrong so I can fix this before it gets too cold outside?

Ronnie S · 10-14-2009

Sounds like you have a fan that's on it's way out and has too much draw. Or a weak alternator. Try turning on other accesories like blower motor and wipers and keep the radiator fan off. (you don't need the fan at 40mph or faster) see if you have the same voltage drop from other accesories.

1slowdsm · 10-15-2009

checked that. No voltage drops from the accessories, just from the fan. I usually just turn the fan off when Im cruising above 40. It stays on anywhere under 30, esp. at stop lights. The fan is the only thing causing voltage drops.

1slowdsm · 11-09-2009

Has anyone tried using the condensor relay to power on both the fans, as on the vfaq? Im curious how well this works. Can someone let me know. I've been trying to figure out this fan problem for some time now and have had no luck. I've even replaced the thermo switch, so now my only resort I can think of is relying on a fan to manually turn on the cooling fan.

TkrPerformance · 11-10-2009

I just us a 60amp fog light relay on all the cars and wire the fan or fans to key on power. I just tap into an open 12v switch power at the fuse box under the hood.

1slowdsm · 11-11-2009

Quote:

Originally Posted by TkrPerformance

I just us a 60amp fog light relay on all the cars and wire the fan or fans to key on power. I just tap into an open 12v switch power at the fuse box under the hood.

LOL. Im too noob at electricals to understand that completely. What do you mean ' wire the fan/fans to key on power"? Explain in a little easier way for a noob like me to understand please?

You dont mean to have the fans on while the car is running do ya?

Right now I have the fans hooked up to a switch that when turned on, will complete the connection and jump the rad. fan relay. I have the fuse in also, hoping it would do something because last time I left the fuse out and too much current was running through to the switch. This is only my temp. problem just incase Im stuck in traffic and my car heats up. I need a better way

Spikesoftail · 11-11-2009

Sounds like if the switch is getting hot you either:

1. have a switch that wont handle enough amperage
2. Fans that are going bad and pulling too much amperage

Fans pulling too much amperage would be my though, something tells me that the thermostat that controls the fan is burned out, being as though you've got it jumpered to a switch. That plug the major drop in voltage when its running. I'd say do and amperge draw test on the fans, or find some good used ones and plug them in.

1slowdsm · 11-11-2009

I've thought about the fans drawing too much amperage because when I first threw this switch in, it didnt start getting hot until a month later, then it got hot really quick. I think my switch is only a cheap 15amp from autozone. My thermo switch was just replaced, hoping it would solve the problem, but the cooling fan still never comes on.