NG 900/9-3 Radiator Fan Test
Contents
Overview
The two-speed cooling fan is controlled from the Integrated Central Electronic Module (ICE). It runs at Low or High speed depending on the coolant temperature. There is no warning light for a faulty fan. The ICE module also controls the temperature gauge in the instrument panel. Regardless of whether the fan is cycling on low or high, the gauge will stay at 9 o'clock.
The cooling fan runs on Low when the coolant temperature is over 100C, and High when over 113C. It also runs on Low to cool the condenser whenever the A/C compressor turns on. If the fan low speed fails, the condenser will overheat. The most common reason is a burned out fan resistor. In warm weather, the fan should run briefly after engine is shut off. If the fan never comes on after the engine is shut off, the low speed circuit may not be working.
- Thermostat opening temp: 89 +/- 2C
- Fan Low speed turn on: 100 +/- 2C
- Fan High speed turn on: 113 +/- 2C
- AC disabled at: 126 +/- 2C
- Temp gauge at mid point (9 o'clock) 85-115C
If the fan resistor burns out, or if the low fan speed circuit fails for other reasons, the fan will continue to cycle on the high setting to cool the engine, but the coolant (and engine) temperature will run about 10-15 degrees C high. The fan may not run after the engine is shut off, and will not come on to cool the condenser. A/C will blow warm air or shut off completely at idle or in start/stop traffic. If the fan is not repaired and the condenser continues to overheat, refrigerant may start to leak, or the A/C compressor may fail.
Testing
References
- Saab EPC 2-1770
- Haynes Ch 3, Section 5
- Haynes Ch 12, Diagram 2
Cooling Fan Relays and Fuses
The Low and High fan control circuits are separate from the ICE module all the way to the fan motor. The cooling fan Low (20-amp) and High (30-amp) relays are located in the engine compartment relay tray, and labeled on the lid of the box. The two fan fuses (30A and 40A) are in the same location.
Testing
The fan can be tested with the engine on or off (but preferrably off), by removing first the "Fan Low" relay, and putting a test lead, or a heavy wire jumper between relay socket contacts #30 and 87. A heavier than normal wire or test lead is required due to the large fan current. The fan should now run on low speed even with engine off. The same test can be repeated with the "Fan High" relay. Use Fuse Taps (from RadioShack etc.) or similar flat contacts in the relay socket to avoid damage to the socket.
Fan Current
To measure the fan current, put a meter set to a 20-amp range in series with the test leads, across contacts 30 and 87. It is safer to test the fan curent with engine off:
Fan Low Fan High Engine Off (12V) 12 Amps 16 Amps Engine On (14V) 14 Amps 19 Amps
Fan Wires
The fan connectors are close to the fan shroud near the battery tray. The picture at left is with the turbo BPV removed. Wire colors are as follows:
- White - fan High
- Green - fan Low
- Black - ground
- Wht/Grn - fan resistor to motor terminal
Fan Resistor
The fan resistor is inside a copper color tube, attached to the fan shroud, below the connectors. The resistor is a cheaply made wire-wound, ceramic-insulated type, about 0.20-0.25 ohms. The resistor is not sold as a separate part by Saab, but it can be easily replaced by a generic 50-75 watt resistor of a similar value.
