Running fan after engine is turned off?

[1988 911 cab]

I have 1988 911 3.2. which is running great! I went on a drive this morning for about 1 hour. However, after about 1 hour I went to clean it out and noticed a fan running from the engine compartment. Is this a coolant fan for the engine and if so how long should this run? I don't want it to drain the battery. Is this an issue? Thanks for any help. I am going on my third year of owning this great car and learn something each year .

[mickey356]

Do you have a cooliant fan?
I had a similar issue but it was my heater blower motor. I tool the fuse out to stop it. I never found the cause and the blower motor is coming out anyway. And yes, it will run down your battery anytime something electric keeps running with the engine off. I cant think of anythng that should run an hour after shut down.
Get your manuel out, see where the runing fan sound is coming from, find out what it is in your manuel, and find a way to disconnect it until you solve the mystery.

[1988 911 cab]

Ok follow up.. I disconnected the battery which caused the fan to stop. Great.. After 30 mins. I reconnected the battery and the fan started again. Not so great.. I then turned on and then off the ac and heater. Fan noise then stopped. I might just have a bad switch. Any thoughts???

[80-911SC]

WOW, factory coolant fan addition to and 88

that is a 1of1 if factory, wow. did you check your water level ?? make sure its not to low because that will make you fan run as the reverse osmosis is trying to produce, assuming you have the factory sealed coolant option. in the meanwhile find you radiator and cap and get back to us soon with a picture ............ thanks

[steely]

The blower switch has a hot lead to it (power at all times), although the bentley manual doesn't give a clear schematic of the switch. It could be as you say, a switch issue, but it may be difficult to nail down.

I was thinking a stuck interior or duct thermostat, if indeed they are in the loop. Next time you run it and this happens, keep an eye on the temperature and time, and see if the eng compartment fan shuts itself off (tstat control) - if not, then do as you did to prevent drain. I would have thought 30 minutes would have been enough tho'.

(was your heater control turned on?)
Search here too, to see if anyone else had this happen.
HTH

on edit: oh yeah, and welcome to the show!

[turbobrat930]

To the original poster, You may have guessed from some fo the responses that your engine is not water cooled.... all 911 based street production cars were air cooled until the 996 series of cars. Your fan is most likely the blower motor for the heating/ air conditioning system... check there...

[86 911 Targa]

Originally Posted by 1988 911 cab

I have 1988 911 3.2. which is running great! I went on a drive this morning for about 1 hour. However, after about 1 hour I went to clean it out and noticed a fan running from the engine compartment. Is this a coolant fan for the engine and if so how long should this run? I don't want it to drain the battery. Is this an issue? Thanks for any help. I am going on my third year of owning this great car and learn something each year .

You don't indicate if you have Auto Heat in your 911.

The heater fan relay, located in the engine compartment, may be the issue.

I suspect that the relay is hanging up.

Here is the location, the "inners", and the circuit.

The item circled in on the component close-up pic is a reed switch.

If so, next time the anomoly surfaces, gently tap the relay & see if the relay opens up, and the fan shuts off.

If it is the relay, $$$$$$$$$$.

Good luck,

Gerry

[steely]

I looked at the bentley sch for the relay and read the switch caption.

they used a reed switch? seems lite duty.

hats off to ya Ger.

[Flieger]

I think by "coolant fan" he meant "cooling fan", as in an auxiliary electric fan to cool the engine, much like the one on Carrera radiator-style oil coolers.

[steely]

At least 4 of us got that

[80-911SC]

just reread first post "coolant fan" not cooling fan

come on you couldn't tell the nature of my post?

what are the odds of him having the first coolant fan is his car?? that would be a 1of1

[Flieger]

I am just saying you do not need to flame him with the sarcasm. I think he knows the car is air cooled. The coolant is air and also oil. Therefore, any oil cooler fans could be called coolant fans, which aid in cooling.

He is grammatically correct, in m opinion.

"Coolant" can describe the substance used to cool or it could be used as an adjective to describe what the noun it is modifying does. A fan that cools by blowing air provides coolant (air) so it is a coolant fan.

I just get a little annoyed at the sarcasm for newbies.

[aj88cab]

There is a temp switch in the oil breather cover plate that is intended to run the engine blower if the oil/engine temp gets too high. It is set pretty high and rarely comes on in my experience. Pull the connector for this temp switch at the breather cover and see if the fan stops. If it does stop the fan, the switch is bad. If pulling the temp switch connector doesn't solve the problem then the engine blower controller mentioned above is bad.

The reed switch does not run the engine blower, it operates the relay for the footwell blowers. The reeds switch only closes when the heater levers are up (or auto heat on) and engine blower is running. I believe the operation of this temp switch "bypasses" the footwell blower relay so the footwell blowers do not run while in this "auxillary cooling" mode.

If tapping on the engine blower controller corrects the problem, it is the engine blower relay in the controller that is hanging up. There are two relays in the controller, one for the engine blower and one for the footwell blowers.

[na2ub]

If your heat lever is up, even the slightest amount, the blower will turn on. I would bet that was the problem. Without starting the car, lift up on your heat lever and you will notice how little it need be elevated to start the blower motor.

[aj88cab]

Certainly a possibility with the ignition switch in the ON position or engine running, but if the engine blower fan runs with the car "OFF", then it points to the temp switch or the controller.

[dshepp806]

Originally Posted by aj88cab

There is a temp switch in the oil breather cover plate that is intended to run the engine blower if the oil/engine temp gets too high. It is set pretty high and rarely comes on in my experience. Pull the connector for this temp switch at the breather cover and see if the fan stops. If it does stop the fan, the switch is bad. If pulling the temp switch connector doesn't solve the problem then the engine blower controller mentioned above is bad.

The reed switch does not run the engine blower, it operates the relay for the footwell blowers. The reeds switch only closes when the heater levers are up (or auto heat on) and engine blower is running. I believe the operation of this temp switch "bypasses" the footwell blower relay so the footwell blowers do not run while in this "auxillary cooling" mode.

If tapping on the engine blower controller corrects the problem, it is the engine blower relay in the controller that is hanging up. There are two relays in the controller, one for the engine blower and one for the footwell blowers.

+1.

Lever switch would require ignition pathways for current (i.e., the ignition would need to be ON). I'd do it in the order that AJ88cab indicated.

Or, just reseat that relay !!

We'll see.

Best,

Doyle

[DRACO A5OG]

Have you found the culprit yet? Have you tried pulling the connector for the Breather Cap Switch?

[DRACO A5OG]

Originally Posted by aj88cab

There is a temp switch in the oil breather cover plate that is intended to run the engine blower if the oil/engine temp gets too high. It is set pretty high and rarely comes on in my experience. Pull the connector for this temp switch at the breather cover and see if the fan stops. If it does stop the fan, the switch is bad. If pulling the temp switch connector doesn't solve the problem then the engine blower controller mentioned above is bad.

The reed switch does not run the engine blower, it operates the relay for the footwell blowers. The reeds switch only closes when the heater levers are up (or auto heat on) and engine blower is running. I believe the operation of this temp switch "bypasses" the footwell blower relay so the footwell blowers do not run while in this "auxillary cooling" mode.

If tapping on the engine blower controller corrects the problem, it is the engine blower relay in the controller that is hanging up. There are two relays in the controller, one for the engine blower and one for the footwell blowers.

Thanks AJ, I found the culprit:



One needs the gasket as well:



It would come on even though the engine temp was at 180-185 degrees this evening.

Jim

[aj88cab]

Originally Posted by aj88cab

The reed switch does not run the engine blower, it operates the relay for the footwell blowers. The reeds switch only closes when the heater levers are up (or auto heat on) and engine blower is running. I believe the operation of this temp switch "bypasses" the footwell blower relay so the footwell blowers do not run while in this "auxillary cooling" mode.
.

Just wanted to correct this statement (red highlight) for future searches. Apparently the FWB will run when the engine blower auxillary cooling mode is activated.

[DRACO A5OG]

Originally Posted by aj88cab

Just wanted to correct this statement (red highlight) for future searches. Apparently the FWB will run when the engine blower auxillary cooling mode is activated.

Verified. Have new (Known Good) relay as well, just to make certain the malfunctioning Thermoswitch did not effect it.

Funny, for the past week it has not turned by itself, all I did was remove cleaned and re-seated the thermoswitch plug