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Discussion Starter · #1 ·
Greetings:

My engine tends to get hot upon doing city driving. However once I am on the hwy, the engine runs much cooler-normal. I just completed my engine oil cooler installation. The cooler is just to the right of the radiator inside the grill area nearer to the bottom. It is not really blocking this portion of the radiator. I have not really notice the fans to cycle as they should. I am thinking possibly a fan relay and or fuse? Again the cooler is kind of tucked to the far rightside (driver's side) lower corner of the radiator. It came out of a 1996 9000CSE donor car, it is a little bigger than the original 900 version, all lines are connected/secure, no leaks. The car only has 174,000 plus original miles on it, what are the chances of both fans being defective? What are the cycle rates for these 2 fans, in terms of keeping the engine cool! Would I just be better off ordering a original size cooler just before next summer, and loop the lines and by pass the cooler for the winter, or should the fans be able to keep the engine cool overall despite my current cooler setup? :confused: !!

Best Regards
 

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The cooler shouldn't be a problem. You have a cooling fan relay and a temperature switch in the radiator. With the engine running, locate the rad switch and jump the terminals together (with the wiring attached). If the fan runs, everything else is ok and the rad switch is faulty.

If that doesn't change anything, remove the fan relay and jump the large pins together. Now jump the rad switch. If the fans run then but didn't on test 1, the relay is likely faulty. If they do run, leave the jumper in place and let the car heat up until the fans should switch on. If they do, the rad switch is ok.
 

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It depends on what you mean by 'running hot'. If the temp climbs as soon as you are sitting in traffic then the system is not doing enough cooling and could have some sludge lying around somewhere.

I had something of the same problem until recently when I changed my heater core. The old one was almost completely blocked, now it takes a long time before the temp starts to rise. You could try using a flushing fluid that breaks down and removes deposits.

Also, if you doubt the integrity of the thermostatic switch you can change it and you can wire up a switch to the 2 terminals and give yourself a means of switching the fan on yourself.
 

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Discussion Starter · #4 · (Edited)
Thanks guys!! I just checked the fan on the driver's side for any play and or resistance via hand rotation. The fan seems to be somewhat resistant and have a slight squeaking sound (feels like faulty bearings?), in addition the blade assembly appears to be a tad bit loose (front to back). The other fan is ok and spins very freely without any resistance and or play. I read the update tech regarding the relay. I will check to see if I have the updated relay. Ironically, I switched relays (spare one) and the fan never activiated. The radiator may also be sludged up too? The radiator that is on the car now had old tranny cooler lines that are not being used because this model has its own tranny cooler too, which leads me to believe that the radiator and the fan are no good, and that the radiator is from another model? The temps kind of creep up nearer to the hot zone, upon venturing in the city. The recently installed engine oil cooler is not leaking and doing well. Do I have to replace the whole dual fan assembly for just one faulty fan? Is the fan unit on the driver's side the actual fan for the a/c or what? Also what is reasonable rotational resistance, I mean this driver's side fan seems tight/resistive. I have been hearing bearing type noises too, at first I thought that it was my turbo, but the turbo seems to be fuctional with decent boost on demand:confused: ! The blades look a bit scuffed up along the edges. Finally, how much of a pita is it to replace the fan unit from start to finish, in addition what is the most practical method in doing so? What further say you? And thanks again for the aforementioned responses they were very helpful, Happy holidays:) !!

Best Regards!

1991 900 turbo 16v 2.0 A.T. 174,000 plus original miles excellent condition
 

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Take off the front grille and feel the radiator while the engine is hot. If there are cold spots, the radiator is clogged, if it's evenly heated, it's probably ok. The second fan comes on only with the aircon. If you swap around the connectors, it will run as the main cooling fan.

What happened when you did the jumper test on the rad switch?
 

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Discussion Starter · #6 · (Edited)
Is heater core replacement overly complicated or is it a smooth transition?:confused: Overall my heater seems to be quite strong, as far as blockage, I am not quite sure, although there quite possibly could be some slight blockage. I might just replace the radiator and fan anyway, just to be certain. Again the radiator looks as though it may have originated from a non-turbo model, whereas the tranny cooler lines are in plain view. Thanks again:) !
philjohnhb said:
It depends on what you mean by 'running hot'. If the temp climbs as soon as you are sitting in traffic then the system is not doing enough cooling and could have some sludge lying around somewhere.

I had something of the same problem until recently when I changed my heater core. The old one was almost completely blocked, now it takes a long time before the temp starts to rise. You could try using a flushing fluid that breaks down and removes deposits.

Also, if you doubt the integrity of the thermostatic switch you can change it and you can wire up a switch to the 2 terminals and give yourself a means of switching the fan on yourself.
What is the longevity of a thermostic switch such as this one? So I could run a toggle switch off the terminals ands into the compartment of the car, and when the toggle isn't active, will the time delay system still have the ability of kicking in as needed? This switch could be a plus factor, particularly when one is engulfed within an influx of heavy traffic during the hot summer within the city and or on the highway. Is there any particular switch, or could I just go to my local radio shack? Thanks in advance:) !!!
 

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The thermostat switch still works even with the manual switch plumbed in. I used an 'extras' switch, the same as the dash switches for HRW, Hazards, A/C & recirc.

The thermostat switches don't last the life of the car and are cheap to replace.

The normal cooling fan is on the Right side (passenger in U.S.) the extra A/C fan is on the Left side. Changing the fan is jest removal of 3 screws. If the other fan is squeaking and there is resistance when you try to turn it by hand then the bearings are gone.
 

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Discussion Starter · #8 ·
I am going to test the radiator switch today. For some reason or another my radiator switch seems to be a modified and or upgraded version. You see, my switch configuration is about the shape and size of my upper rad hose, (aluminum/metal tube). This hose sized connector is fused and or lodged into a split upper radiator hose. The switch itself is connected to this unit. I didn't notice any switch connector on the side of the radiator. The wiring connections are the same as with most 900's, but again this additional connector has me a bit confused? It will make it easier to check but is this connector from another earlier and or later model Saab? Again my radiator doesn't appear to be an original version, whereas my trans-cooler line connections are not in use (seperate trans cooler underneath pass-side bumper). Also is it possible that the wires might be reversed? And should the fan on the driver's side spin freely without any sort of resistance? I didn't notice any cold spots, and both upper/lower hoses are hot. :confused: thanks!
cdaly said:
Take off the front grille and feel the radiator while the engine is hot. If there are cold spots, the radiator is clogged, if it's evenly heated, it's probably ok. The second fan comes on only with the aircon. If you swap around the connectors, it will run as the main cooling fan.

What happened when you did the jumper test on the rad switch?
 

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Discussion Starter · #9 ·
philjohnhb said:
The thermostat switch still works even with the manual switch plumbed in. I used an 'extras' switch, the same as the dash switches for HRW, Hazards, A/C & recirc.

The thermostat switches don't last the life of the car and are cheap to replace.

The normal cooling fan is on the Right side (passenger in U.S.) the extra A/C fan is on the Left side. Changing the fan is jest removal of 3 screws. If the other fan is squeaking and there is resistance when you try to turn it by hand then the bearings are gone.
I am glad that it is my a/c fan that has resistance, no worries for the moment, given the fact that winter is now enroute:roll: ! I will simply pick up another fan shroud/2fans and keep then on hand for a next spring install project. As I had mention on my other post, I am a bit confused about this particular type of thermo-switch configuration? I suspect that it may be the switch and or some partial blockage somewhere? All of my fuses seem to be ok, and again, I checked my relays. I am going to do a seperate switch this weekend for the radiator. I shall keep everyone posted should I encounter any further findings and or solutions. Thanks again guys you have been extremely helpful and responsive! This is my very first Saab and I certainly could use all the advice and experiences of other Saab owners:) !

Best Regards!
 

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The switch in the radiator top hose is the aircon overheat cutout switch. The rad fan switch is in the left hand side of the radiator, near the top with two wires in orange rubber boots connected to it.
 

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Discussion Starter · #11 ·
cdaly said:
The switch in the radiator top hose is the aircon overheat cutout switch. The rad fan switch is in the left hand side of the radiator, near the top with two wires in orange rubber boots connected to it.
Thanks:) ! I was wondering. I will look into the integrity of the rad switch and I shall keep you guys posted. What exactly is the aircon overheat cut out switch?;oops:


Best Regards!
 

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It switches off the aircon if the engine gets too hot. This is because the aircon condensor is right in front of the radiator so it warms the air cooling the engine. Switching off the aircon allows the radiator to be cooled that bit faster.
 

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Discussion Starter · #13 ·
cdaly said:
It switches off the aircon if the engine gets too hot. This is because the aircon condensor is right in front of the radiator so it warms the air cooling the engine. Switching off the aircon allows the radiator to be cooled that bit faster.
Interesting, Thanks!:)
 

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cdaly said:
Take off the front grille and feel the radiator while the engine is hot. If there are cold spots, the radiator is clogged, if it's evenly heated, it's probably ok. The second fan comes on only with the aircon. If you swap around the connectors, it will run as the main cooling fan.
That's not the case with my 900's - all of them (even the 81 turbo) turn on both fans when the thermoswitch cuts in. If the A/C fuse is pulled the second fan won't run since the relay for the A/C has no power, but the A/C doesn't have to be turned on. If the A/C is turned on though, the second fan runs continuously despite the action of the thermoswitch. I'm not sure that the later -year C900's were wired like this by default - I seem to recall something on Tom Townsend's site saying 90+ C900's need a mod for the second fan to run with the first fan.

Craig.
 

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Discussion Starter · #15 ·
c900 said:
That's not the case with my 900's - all of them (even the 81 turbo) turn on both fans when the thermoswitch cuts in. If the A/C fuse is pulled the second fan won't run since the relay for the A/C has no power, but the A/C doesn't have to be turned on. If the A/C is turned on though, the second fan runs continuously despite the action of the thermoswitch. I'm not sure that the later -year C900's were wired like this by default - I seem to recall something on Tom Townsend's site saying 90+ C900's need a mod for the second fan to run with the first fan.

Craig.
Its funny that you mentioned this! Upon further observation this afternoon, I noticed the temp to rise about 2/3 of the way to the hot marker, and then all of a sudden both fans kicked on!! They stayed on for a minute or so and then cut off (various cycle intervals). They appeared to cycle very strong, in fact the motor seemed to pause for a split second just before both fans came on. :confused: Another interesting thing that I observed was the fan on the left that I thought or at least felt some resistance via hand rotation, kicked on once I turned the car off! The passenger's side fan was cycling at times by itself, and for the most part in conjunction with the other fan. The temps never reached the hot marker although it got up there nearer to 2/3 and 3/4 of the time. I just changed my oil and oil filter (Pennzoil Platinum Full Synthetic 10w-30 with one purolator premium plus oil filter, nice flow good filtration), maybe this synthetic oil will aid in keeping things a bit cooler? I figured taht I will just change the filter again at 2500 miles, and change the oil and filter again at 5500-6000 miles, where 99% of my driving is hwy miles 750-1,000 per a week! Anyways, not to get off the subject but I was thinking my water pump bearings were getting weak (slightly noisy)? However I have plenty of pressure in my coolant hoses and the coolant is up to level. Do these cars generally get warm like this when the motor runs for a period of time? Also how long should either of the 2 fans be cycling in terms of intervals? Might a defective relay allow them to cycle too short of a interval? I want to get a toggle line going, whereas I may cycle the fans more frequently and longer manually. I might even look into another radiator and or start replacing various components of the cooling system. Please all of your feed back would be greatly appreciated!! Thanks again guys! 1991 900SE 16Valve 2.0 A.T. with 174,624 original miles in excellent condition.
 
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