From: Jim Bailey [jim@928intl.com] Sent: Thursday, July 19, 2001 1:20 PM To: 928 Subject: [928] RE: Best Cooling - Fan Shroud or no Fan Shroud The standard 85 C degree thermostat tries to maintain a constant minimum temp of 185 F the auxiliary electric fan switch in the radiator (78-86) has a temperature setting of 92 degree C or 197 F which corresponds to about the "second " white line . The range of 185 -197 F is what the engine is designed to operate in ......You can install a lower temperature thermostat 74 C ( 165 F ) and a 75 C (fans switch ) . Which means the electric fan will pretty much run all the time and the engine will be try to be colder than it was designed to be and make slightly less horsepower . If you notice the temperature rising when you are sitting idling , put the car in neutral and rev the engine to about 2,500 RPM hold it there for a couple of minutes . If the temp starts dropping it is a good indication that the mechanical fan clutch ( with silicone) is beginning to fail . Logic behind this conclusion ..... revving the engine actual generates more heat but the increased air flow through the radiator from the fan spinning faster more than compensates for the extra heat ..... As has been mentioned removing the plastic shroud would make the fan nearly useless . The " aftermarket " fans which attach to the radiator core only cool the portion of the radiator that they cover doing nothing for the rest of the radiator . From: Wally Plumley [mailto:wplumley@bellsouth.net] Sent: Thursday, May 30, 2002 9:32 AM To: 928 Subject: [928] Re: 1985 electric fan issue- again At 01:01 AM 5/30/02, Jack wrote: >Ok, there seems to be conflicting thoughts on this one. Some say is should >hardly ever come on, some say it should come on when you turn on your AC. On the pre-S4 models, the electric cooling fan is operated by three (5-speed) or four (automatics) sensors. A coolant temp sensor located in the lower forward face of the radiator end cap. This sensor is open below the set coolant temp, closed above that temp. You can buy sensors with different trigger temps. To test the switch, pull the harness off, check continuity of the switch. Should be open when the radiator is very cool, closed when the radiator is above the trigger temp. To test the fan circuit, pull the harness off, turn the ignition switch on, and short between the contacts in the harness. The fan should run. If it doesn't, check fuse # 29 (25 amp) or relay XVIII. A freon temp sensor located on the stem of the receiver/dryer. This sensor is open below the set temp of the freon in the receiver/dryer, closed above that point. Tests are the same as for the coolant temp sensor. This sensor does not appear to be very effective on most cars. A transmission fluid temp sensor located on the torque convertor, on automatics only. This sensor is open below the set temp of the transmission fluid, closed above that point. Tests are the same as for the coolant temp sensor. These three temp sensors work by grounding terminal 85 of relay XVIII, triggering the relay. The relay contacts are fed from bus X (ignition on) thru fuse # 29 to relay terminal 30, and the output contact (terminal 87) runs directly to the fan, running the fan at full speed. In addition, there is an air temp sensor mounted on the intake plenum. This sensor is fed power thru fuse #23 regardless of ignition switch position, and is open when the air in the intake is below the set temp, closed above that temp. When the sensor closes, power is fed thru a resistance to the cooling fan, causing it to run at a lower speed. This is primarily for cool-down after engine shut-down. >I >connected the sensor behind the oil refill cap that point towards the front >of the car. I connected them with a screwdriver and the fan did not come on >with the ignition off. I don't know if this means that my fan is shot. This sensor has nothing to do with the cooling fan operation. >My >car starts to run hot if left idling in one place. I revved it for 2-3 >minutes at about 2300 RPM and it did not decrease the temperature. Car cools >down as soon as it starts moving. My owners manual says that the electric >fan should work, if it doesn't, check the fuse, changed it, it was blown. >Before I go out and buy a new electric fan, anyone have any suggestions how >to deduce potential issues? You appear to have two different problems - the belt driven fan is ineffective, probably because the silicone-filled clutch on the fan is slipping and not moving sufficient air; and the electric fan is not operating. There may also be other problems - the engine may not be overheating at all, but the gauge may be giving you a false reading; or the bottom engine compartment pan and/or the spoiler may be missing, allowing hot air to recirculate thru the radiator. The silicone clutch can usually be refilled - instructions are on Greg Nichols' tips site at http://www.nichols.nu/tips.htm Wally Plumley 928 Specialists -----Original Message----- From: Jay Kempf [mailto:jkempf@tds.net] Sent: Wednesday, May 07, 2003 7:14 PM To: 928 Subject: [928] RE: Electric Cooling Fan Trouble > -----Original Message----- > From: Brian Buckley [mailto:brian.buckley4@verizon.net] > Sent: Wednesday, May 07, 2003 8:23 AM > To: 928 > Subject: [928] Electric Cooling Fan Trouble > > > Greetings, > > The electric cooling fan on my OB has given up the ghost. It refuses to > start to cool off the motor. Since I'm kinda new at this, does anyone > have any suggestions where I can start to troubleshoot this problem? I > bought the car last winter, so this is the first time I have really needed > the fan. The car doesn't overheat, but its running real warm (needle on > the gauge on the upper white line) > > Oh yeah, its a 79 euro model, if that makes a difference. Thanks in > advance! > > Brian If you are talking about the cooling fan in front of the radiator that is only supposed to come on when the needle is near or in the red by design. It is triggered by two things. First the switch at the lower front left of the radiator. Second by the overtemp switch on the receiver dryer for the AC system. On the early cars this fan almost never comes on. When the lower part of the radiator starts getting cancer it will keep it from coming on at all. To test find the switches and bridge the spade terminals in the harness. If the fan runs it means the switch is bad. If not it means you need to work your way back to the fuse and the relays. The fuse is a good place to start. Jay Kempf