15 replies to this topic

[d15a3power]

OK, the oil & antifreeze look fine. I had the radiator power-flushed 1000 miles ago.

Idle kicks down after it warms up & idles smoothly.

The radiator fan never turns on, even when the temp is near red-line. The fuse is fine. It only comes on when I turn on the A/C. Even then, the temp never falls; I tried turning on the heat, but still the temp never falls. It only falls when the car is moving fast....

I hope its a thermostat-- I had electrical issues with the A/C before & throwing relays at the car got to be expensive....

Any ideas?

[cbstdscott]

If you fan only comes on when the A/C comes on, you have an issue to deal with.

Scott

[Mark L]

The radiator fan never turns on, even when the temp is near red-line. The fuse is fine. It only comes on when I turn on the A/C. Even then, the temp never falls; I tried turning on the heat, but still the temp never falls. It only falls when the car is moving fast....
Any ideas?

The good news is if the fan is turning on with the AC, the fan, fan timer and fan relay is more than likely good.

The Fan circuit is simple. On the bottom of the radiator between the drain plug and the lower radiator hose is a thermo sensor which will close at 190F. Take the 2 wire plug off the thermo sensoe and connect the 2 wires using a short wire or paper clip. With the key on the fan should spin. If it does, the sensor is bad.

[Richter77]

+ when the thermostat fails in the closed position, It will blow all the coolant out the overflow can.

[Madkore]

Actually, you probably do have a bad fanswitch.

The AC system will automatically turn on the fan when engaged.

You can check the fanswitch by simply bypassing it with a short wire when you engine is hot.

Get a short wire and crimp the right bullet ends on to it, and then install it on the wires to the fanswitch.

Your fan will always be on, but it's better than overheating the engine and warping the head.

You should also make sure the coolant system has been properly bled to remove any air in the system.

MK

[d15a3power]

Thanks for the advice-- I'll try to check this out tomorrow. I work till 3:30am, so it's hard to find daylight time to check this out.

The main reason I was thinking thermostat is that when the fan does come on, the temp doesn't go down-- it's like the hot engine coolant isn't getting to the radiator. I also got advice to feel the main hose for flow...

[DEIVIONCRX]

Sounds like a bad temp switch to me aswell, Grab a paper clip and make it into a U shape and stick it between the 2 bullet terminals and see if the fan comes on when you turn the key on. If it does you can either check the switch with a Multi-meter to make sure its dead or just replace it.

[d15a3power]

Well, I couldn't get to the fan switch, so I simply left the A/C on & drove. ( The fan stayed on) It's only like 75F today. I've done this plenty of times & the temp stayed in the middle.

I drove down the highway & it stayed in the middle. When I got home, the temp rose to nearly overheating-- not quite as fast as when the fan was off.

I turned the car off & let it sit for 15 min. I started it & let it run again w/ the A/C on & it got hot but not quite to overheating. The idle kept kicking up & down every 10 sec. or so. There seems to be flow thru the top radiator hose.

Is the consensus still that it's just the fan switch?

[Elias]

when AC condensor fan need to be on?

[Greg Gauper]

You should only need the fan if you are idling or going slower than 10-15mph. Once you get above 15mph on the street, you don't need the fan as there is more tahn enough air blowing across the radiator at that speed to keep the engine cool...in fact Jay & removed the fans from our racecars for weight savings.

So does it overheat if you drive on the highway with the A/C off?

If the temp is okay on the highway, then the problem is probably your temp switch for the fan. Do the paperclip trick to see if the fan runs. If it does and you don't have an opportunity to replace the switch, you can temporarily rig up a toggle switch with two wires running back to the driver's area where you operate the switch manually.

If the temp is not okay on the highway, then you have other cooling issues. But the fact that the temp is fine when you run with the A/C on (which makes the engine work harder and puts a heavier load on the cooling system) leads me to think it is a simple temperature switch problem.

Edited by Greg Gauper, 05 July 2008 - 12:14 PM.

[Rampage]

Just about every car with A/C will command the condenser fan and in most cases the main fan as well when you switch the system on.

If you turn on your A/C and both fans spin, you can verify that the fan does in fact work.

If its not the fan, the most likely culprit is the switch. Jumping the two wires to it to complete the circuit is the best way to test it.

My rad fan switch does not work in my car, but i've wired it to a switch to send the power when I choose. Sometimes I forget and the guage gets up there, but I usually catch it before its pinned

Cheers,
Mark

[d15a3power]

I jumped the temp switch with a paperclip as suggested. It will still get to nearly overheating, but at least the A/C doesn't have to be on all the time.

The temp is fine at speeds over 30mph or so. To answer the question, no it doesn't overheat on the highway with the A/C off.

The concern is that the fan doesn't seem to be as effective as it should be...it won't drop the temp like moving at 30+ does.

[84b18]

I jumped the temp switch with a paperclip as suggested. It will still get to nearly overheating, but at least the A/C doesn't have to be on all the time.

The temp is fine at speeds over 30mph or so. To answer the question, no it doesn't overheat on the highway with the A/C off.

The concern is that the fan doesn't seem to be as effective as it should be...it won't drop the temp like moving at 30+ does.

maby also becuse at 30+ you're water pump is running faster

i have noticed even if i coast very rapidly down a hill for a wial cars don't cool tell i rev the engine higher.

[3gencivic]

my 86si hatch is doing this. i know that its my thermostate as i over worked the car hauling to much weight an i was even smealing a sweet smell as in burnt coolent. before this my temp gauge never was above half now its always are 3.4 so i jsut need time to swap it out.

my 87 1500S is also one that runs worm. i find its jsut the termostates.

[badpenny]

anyone think it might be the waterpump?