Cooling Fan Overtime
07-27-2018 | 12:01 PM
#31
Thread Starter
Instructor
Joined: Apr 2014
Posts: 235
Likes: 9
From: Creede, CO
Swenny, PaulD,
So far the switch has worked. I'm heading out to super hot California in a few days and that will be the real test of my bodge-job repair.
I have checked the thermostat and the thermoswitch and they seem to be working correctly. I had thought that the thermostat might be a higher temperature than the thermoswitch but my testing showed that everything was at the stock settings and functioning correctly.
I replaced the water pump and coolant at the last timing belt change two years ago. My experience diagnosing and repairing this car has shown me that replacing parts, even when it seems obvious that they're defective, doesn't always solve the problem. Since this relay is so expensive, I decided to see how well this work-around will work before spending money on a part that might or might not be the real source of the problem.
Perry
So far the switch has worked. I'm heading out to super hot California in a few days and that will be the real test of my bodge-job repair.
I have checked the thermostat and the thermoswitch and they seem to be working correctly. I had thought that the thermostat might be a higher temperature than the thermoswitch but my testing showed that everything was at the stock settings and functioning correctly.
I replaced the water pump and coolant at the last timing belt change two years ago. My experience diagnosing and repairing this car has shown me that replacing parts, even when it seems obvious that they're defective, doesn't always solve the problem. Since this relay is so expensive, I decided to see how well this work-around will work before spending money on a part that might or might not be the real source of the problem.
Perry
07-27-2018 | 01:07 PM
#32
Racer
Joined: Aug 2015
Posts: 344
Likes: 6
From: Greater Phoenix Area
I think that the goal is to repair the problem rather than work around it. My first '24S the fans stayed on all the time and drained the battery. I used to disconnect the battery every time that I parked. Then there was that time that I was too lazy to and the car enjoyed a tow home. I fixed the problem(rad fan switch). Two years is about normal for a coolant change. Troubleshooting is about isolating the trouble area (one component at a time). You may have to check,re-check,re-check and re-check to get it right. You're driving a Porsche. Not everyone cares to or can. It comes at a price.
07-27-2018 | 03:08 PM
#33
Rennlist Member
Joined: May 2004
Posts: 2,822
Likes: 171
From: Poconos PA
I measured the current to activate one relay inside the can, and it looks like it draws 100mA. I activated two and left it on for about 15 minutes, and it is barely warm to the touch.
I would be most concerned with your getting very hot to the touch. I'm surprised it doesn't blow a fuse. You run the risk of causing a fire or burning through some wires in the harness.
If you have to drive it, I would pull the whole relay, and hope you don't get stuck in traffic.
I would be most concerned with your getting very hot to the touch. I'm surprised it doesn't blow a fuse. You run the risk of causing a fire or burning through some wires in the harness.
If you have to drive it, I would pull the whole relay, and hope you don't get stuck in traffic.
07-27-2018 | 10:05 PM
#34
Rennlist Member
Joined: Jan 2015
Posts: 2,936
Likes: 16
From: Paso Robles, CA (Under the lift)
Swenny, PaulD,
So far the switch has worked. I'm heading out to super hot California in a few days and that will be the real test of my bodge-job repair.
I have checked the thermostat and the thermoswitch and they seem to be working correctly. I had thought that the thermostat might be a higher temperature than the thermoswitch but my testing showed that everything was at the stock settings and functioning correctly.
I replaced the water pump and coolant at the last timing belt change two years ago. My experience diagnosing and repairing this car has shown me that replacing parts, even when it seems obvious that they're defective, doesn't always solve the problem. Since this relay is so expensive, I decided to see how well this work-around will work before spending money on a part that might or might not be the real source of the problem.
Perry
So far the switch has worked. I'm heading out to super hot California in a few days and that will be the real test of my bodge-job repair.
I have checked the thermostat and the thermoswitch and they seem to be working correctly. I had thought that the thermostat might be a higher temperature than the thermoswitch but my testing showed that everything was at the stock settings and functioning correctly.
I replaced the water pump and coolant at the last timing belt change two years ago. My experience diagnosing and repairing this car has shown me that replacing parts, even when it seems obvious that they're defective, doesn't always solve the problem. Since this relay is so expensive, I decided to see how well this work-around will work before spending money on a part that might or might not be the real source of the problem.
Perry
I own and operate a 944 in Paso Robles and it gets hot here (today's high was 104F). I've never had cooling problems (at least not yet). That relay really does sound like an electrical fire waiting to happen. That could be dire under the wrong circumstances.
PS: I went to second grade in Taft CA, between Paso and Bakersfield. It gets really hot there. We actually fried an egg on the sidewalk once. Really. One of us stole an egg from the fridge and we fried it on the sidewalk. Weird what 7 year old kids will do sometimes
Regards,
07-27-2018 | 10:34 PM
#35
Burning Brakes
Joined: Jul 2014
Posts: 944
Likes: 40
From: SoCal
I think my point was missed.
The fans draw a lot of current, a lot.
If there is any resistance in the relay wiring, relay contacts, circuit board, or solder joints, that will make heat.
Open up the relay can and check the condition.
Plug it in and see what gets hot.
Then fix it.
Or borrow one and try it.
If you leave it as a manual switch, here's what will happen:
One day you will forget to turn the fans on.
While the car is parked.
On a hot day.
The engine will get hot.
Very hot.
It will puke out all of the coolant.
Without coolant the head will warp, the head gasket will blow, or the engine will seize.
The 944 engine will not start.
Then the fan relay won't matter anymore.
The fans draw a lot of current, a lot.
If there is any resistance in the relay wiring, relay contacts, circuit board, or solder joints, that will make heat.
Open up the relay can and check the condition.
Plug it in and see what gets hot.
Then fix it.
Or borrow one and try it.
If you leave it as a manual switch, here's what will happen:
One day you will forget to turn the fans on.
While the car is parked.
On a hot day.
The engine will get hot.
Very hot.
It will puke out all of the coolant.
Without coolant the head will warp, the head gasket will blow, or the engine will seize.
The 944 engine will not start.
Then the fan relay won't matter anymore.
07-28-2018 | 04:54 AM
#36
Instructor
Joined: Mar 2016
Posts: 191
Likes: 16
I think my point was missed.
The fans draw a lot of current, a lot.
If there is any resistance in the relay wiring, relay contacts, circuit board, or solder joints, that will make heat.
Open up the relay can and check the condition.
Plug it in and see what gets hot.
Then fix it.
Or borrow one and try it.
If you leave it as a manual switch, here's what will happen:
One day you will forget to turn the fans on.
While the car is parked.
On a hot day.
The engine will get hot.
Very hot.
It will puke out all of the coolant.
Without coolant the head will warp, the head gasket will blow, or the engine will seize.
The 944 engine will not start.
Then the fan relay won't matter anymore.
The fans draw a lot of current, a lot.
If there is any resistance in the relay wiring, relay contacts, circuit board, or solder joints, that will make heat.
Open up the relay can and check the condition.
Plug it in and see what gets hot.
Then fix it.
Or borrow one and try it.
If you leave it as a manual switch, here's what will happen:
One day you will forget to turn the fans on.
While the car is parked.
On a hot day.
The engine will get hot.
Very hot.
It will puke out all of the coolant.
Without coolant the head will warp, the head gasket will blow, or the engine will seize.
The 944 engine will not start.
Then the fan relay won't matter anymore.
07-28-2018 | 07:57 AM
#37
Advanced
Joined: Dec 2017
Posts: 81
Likes: 4
From: Miami Florida
Another idea
I think you may have an old fan that is creating great resistance therefore the additional energy required to spin the fan is causing your problems and heating up your relay.
If the fan is old has bad bearings it’s a lot like riding a bike in the highest hardest gear going uphill and therefore you have to work harder to move and you sweat and heat up. Same in your car. It’s also a lot like having a short in your system. It should blow the fuse but it’s probable just boarderline below the amperage for that therefore things in the system heat up ie your relay a delicate vunerable part.
Test the fan alone if it sounds old and crappy and runs slow my guess is you have some worn windings, dirty contacts or the bearing or whatever spins in there is shot. Put a new fan in there. No Porsche should be rolling around with a manual switch. Fix the system and let it do what it was meant to do.
If the fan is old has bad bearings it’s a lot like riding a bike in the highest hardest gear going uphill and therefore you have to work harder to move and you sweat and heat up. Same in your car. It’s also a lot like having a short in your system. It should blow the fuse but it’s probable just boarderline below the amperage for that therefore things in the system heat up ie your relay a delicate vunerable part.
Test the fan alone if it sounds old and crappy and runs slow my guess is you have some worn windings, dirty contacts or the bearing or whatever spins in there is shot. Put a new fan in there. No Porsche should be rolling around with a manual switch. Fix the system and let it do what it was meant to do.
Last edited by 911Ragtop; 10-17-2018 at 08:30 AM.
07-28-2018 | 08:57 AM
#38
Drifting
Joined: Feb 2014
Posts: 2,585
Likes: 121
From: smoky mountains
pull the fan relay and check the TF terminal to ground.
infinite resistance points to a problem with the relay. (the relay springs might have become weak due to the heat of continuous operation)
zero resistance points to a problem with the harness/switches.
with the high pressure ac switch and the radiator mounted switch unplugged at the switches, check the resistance again. if it reads zero, there is an issue with the harness.
infinite resistance points to a problem with the relay. (the relay springs might have become weak due to the heat of continuous operation)
zero resistance points to a problem with the harness/switches.
with the high pressure ac switch and the radiator mounted switch unplugged at the switches, check the resistance again. if it reads zero, there is an issue with the harness.
07-28-2018 | 11:57 PM
#41
Nordschleife Master
Joined: Jun 2007
Posts: 6,769
Likes: 298
From: Palm Beach, Florida
As seems to be the case these days the third party vendors of genuine parts are more expensive than the official Porsche dealerships who sell online such as Sunset Porsche
07-29-2018 | 12:32 AM
#42
Rennlist Member
Joined: Jan 2015
Posts: 2,936
Likes: 16
From: Paso Robles, CA (Under the lift)
Yep, I suppose that's a good reason to check the fans before replacing the relay, especially since the OP already replaced the relay once.
I was pricing window relays awhile ago, they aren't cheap either. Luckily my problem was the switch, not the motor or the relay.
I was pricing window relays awhile ago, they aren't cheap either. Luckily my problem was the switch, not the motor or the relay.
07-29-2018 | 04:36 PM
#45
Instructor
Joined: Mar 2016
Posts: 191
Likes: 16
Let me throw out my left handed right brained Amish dude solution. I think you may have an old fan that is creating great resistance therefore the additional energy required to spin the fan is causing your problems and heating up your relay.
If the fan is old has bad bearings it’s a lot like riding a bike in the highest hardest gear going uphill and therefore you have to work harder to move and you sweat and heat up. Same in your car. It’s also a lot like having a short in your system. It should blow the fuse but it’s probable just boarderline below the amperage for that therefore things in the system heat up ie your relay a delicate vunerable part.
Test the fan alone if it sounds old and crappy and runs slow my guess is you have some worn windings, dirty contacts or the bearing or whatever spins in there is shot. Put a new fan in there. No Porsche should be rolling around with a manual switch. Fix the system and let it do what it was meant to do.
If the fan is old has bad bearings it’s a lot like riding a bike in the highest hardest gear going uphill and therefore you have to work harder to move and you sweat and heat up. Same in your car. It’s also a lot like having a short in your system. It should blow the fuse but it’s probable just boarderline below the amperage for that therefore things in the system heat up ie your relay a delicate vunerable part.
Test the fan alone if it sounds old and crappy and runs slow my guess is you have some worn windings, dirty contacts or the bearing or whatever spins in there is shot. Put a new fan in there. No Porsche should be rolling around with a manual switch. Fix the system and let it do what it was meant to do.
Sorry, just re read the post and understand when you said "resistance" you meant mechanical not electrical resistance, thought I'd leave the post for Ohm's law equation
Last edited by aussie944cab; 07-29-2018 at 06:27 PM.