radiator fans

MR.twooooo · 03-19-2006, 02:15 PM

when the ignition is on the radiator fans come on and stay on even when the engine is cold . I'v checked a few of the relays and I can't figure out what the problem is.
any ideas

Gairloch · 03-19-2006, 02:31 PM

One possible reason is that the coolant temperature sensor in the radiator has kicked the bucket.

Anyone know if this should throw a code?

MR.twooooo · 03-19-2006, 02:34 PM

is that the sensor on the driverside on the bottom? if so I'v already checked it with a voltmeter

N8s93turbo · 03-19-2006, 03:02 PM

mine does the same, fan is always on, no codes.

GaToy · 03-20-2006, 07:51 PM

Yeah it's a bad switch. The if the fan is not coming on you can unplug the switch and if the fan is o.k. the fan should come on. plug it back in and if the engine is cool, it should go back off.

~C.C.~

TheAmazingDave · 03-20-2006, 09:40 PM

Another cause, and pretty common it seems, of the radiator fans running full blast as soon as you turn on the ignition is a bad or missing "A/C Amplifier" module. If you have stripped out the A/C and ductwork you surely took the A/C Amplifier out, too.

The A/C Amplifier controls the vehicle's cooling system fans on A/C equipped cars. If it goes bad or is unplugged the system goes in to a failsafe mode and the fans run full blast to protect from overheating.

You need to test the coolant temperature sensor in the front radiator with an ohm meter, not a volt meter. Below 181 degrees Farenheit the radiator temperature sensor should have continuity, or 0 ohms resistance, between the two terminals. Above that temperature the switch should open and the meter will read no continuity, or infinite resistance. If that checks out the next step is the fan circuit relay or A/C Amplifier.

seven_mgte · 03-21-2006, 09:20 PM

I have an amplifer which is not being used (due to extensive rewiring) if anyone needs one.

CpuZapper · 03-22-2006, 06:20 PM

My '86 has a weird issue I've been too lazy to track down, but it may be relevant. If you turn the car from IGN to ACC really slowly, the rad fans come on full blast. I'm not sure if it's from a bad ign. switch, something being on when the rest of the system is off, or just a normal anomaly, but it's just some extra info to consider.

yellowwood · 10-10-2007, 09:46 AM

My fans run all the time too.

The radiator fan switch checked out. Swapped the fan control module in the rear trunk...no dice.

Interestingly enough, I was working on my MAF and noticed a dangling wire connector that is nearly identical to the radiator fan switch connector.
I also noticed a lot of after market hose clamps on a nearby coolant hose.

Can anyone tell me what I am missing from this area?

Could this be why my fans run and run and run?

03-19-2006, 02:15 PM	#1 (permalink)
MR.twooooo Some Skills Join Date: Mar 2006 Location: Alabama Posts: 55 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	radiator fans when the ignition is on the radiator fans come on and stay on even when the engine is cold . I'v checked a few of the relays and I can't figure out what the problem is. any ideas

10-10-2007, 09:46 AM	#9 (permalink)
yellowwood No Skills Join Date: Oct 2007 Location: Indiana, USA Posts: 6 Thanks: 0 Thanked 0 Times in 0 Posts My Google Map iTrader Rating: (0/0% )	'85 Same problem. My fans run all the time too. The radiator fan switch checked out. Swapped the fan control module in the rear trunk...no dice. Interestingly enough, I was working on my MAF and noticed a dangling wire connector that is nearly identical to the radiator fan switch connector. I also noticed a lot of after market hose clamps on a nearby coolant hose. Can anyone tell me what I am missing from this area? Could this be why my fans run and run and run?

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

03-19-2006, 02:31 PM	#2 (permalink)
Gairloch Dreaming of apexes Join Date: Aug 2005 Location: Minneapolis, MN Posts: 5,313 Thanks: 139 Thanked 296 Times in 264 Posts Blog Entries: 4 My Google Map iTrader Rating: (7/100% )	One possible reason is that the coolant temperature sensor in the radiator has kicked the bucket. Anyone know if this should throw a code?

03-19-2006, 02:34 PM	#3 (permalink)
MR.twooooo Some Skills Join Date: Mar 2006 Location: Alabama Posts: 55 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	is that the sensor on the driverside on the bottom? if so I'v already checked it with a voltmeter

03-19-2006, 03:02 PM	#4 (permalink)
N8s93turbo TEAM A.S.S. RACING Join Date: Feb 2005 Location: Mississippi/Pennsylvania Posts: 2,450 Thanks: 5 Thanked 26 Times in 16 Posts My Google Map iTrader Rating: (14/100% )	mine does the same, fan is always on, no codes.

03-20-2006, 07:51 PM	#5 (permalink)
GaToy '86 Sunroof Join Date: Feb 2006 Location: Fort Valley, Ga Posts: 55 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	Yeah it's a bad switch. The if the fan is not coming on you can unplug the switch and if the fan is o.k. the fan should come on. plug it back in and if the engine is cool, it should go back off. ~C.C.~

03-20-2006, 09:40 PM	#6 (permalink)
TheAmazingDave Cage Fighter Join Date: Mar 2005 Location: San Jose, CA Posts: 1,112 Thanks: 13 Thanked 7 Times in 7 Posts My Google Map iTrader Rating: (0/0% )	Another cause, and pretty common it seems, of the radiator fans running full blast as soon as you turn on the ignition is a bad or missing "A/C Amplifier" module. If you have stripped out the A/C and ductwork you surely took the A/C Amplifier out, too. The A/C Amplifier controls the vehicle's cooling system fans on A/C equipped cars. If it goes bad or is unplugged the system goes in to a failsafe mode and the fans run full blast to protect from overheating. You need to test the coolant temperature sensor in the front radiator with an ohm meter, not a volt meter. Below 181 degrees Farenheit the radiator temperature sensor should have continuity, or 0 ohms resistance, between the two terminals. Above that temperature the switch should open and the meter will read no continuity, or infinite resistance. If that checks out the next step is the fan circuit relay or A/C Amplifier.

03-21-2006, 09:20 PM	#7 (permalink)
seven_mgte Cage Fighter Join Date: Aug 2005 Location: Coquitlam, BC.ca Posts: 327 Thanks: 0 Thanked 7 Times in 7 Posts My Google Map iTrader Rating: (0/0% )	I have an amplifer which is not being used (due to extensive rewiring) if anyone needs one.

03-22-2006, 06:20 PM	#8 (permalink)
CpuZapper RallyRacer Join Date: Mar 2005 Location: Portland, OR Posts: 482 Thanks: 7 Thanked 25 Times in 22 Posts My Google Map iTrader Rating: (1/100% )	My '86 has a weird issue I've been too lazy to track down, but it may be relevant. If you turn the car from IGN to ACC really slowly, the rad fans come on full blast. I'm not sure if it's from a bad ign. switch, something being on when the rest of the system is off, or just a normal anomaly, but it's just some extra info to consider.