Bentley No Help:318is WITHOUT Mechanical Radiator Fan

[talisman318is]

How to diagnose problem with fan not working? Temp sending switch unit or relay?

My 95 318is has no auxiliary fan in front of radiator and no mechanical fan. Apparently for some few models ~95 the 318is was configured with the electric radiator fan used on some M44 engines. Bentley (again) says take it to the BMW dealer nearest you and there isn't one near.

The fan will work and I can avoid overheating by turning A/C on -- which will cause the electric fan mounted on the engine side of the radiator to operate. However, if I don't have A/C on and am not driving at highway speeds the car overheats and radiator cap vents coolant. No head damage, not bad thermostat, water pump ok. So . . . how do I diagnose/troubleshoot?

My first post to this forum was because the electric fan failure causing the overheat caused the radiator expansion tank to blow. That replacement was sort of easy -- but not without difficulties. With weather warming up, I'd like the fan to operate when it needs to without having to have the A/C on. The fan problem became apparent when the overheating continued. Again, I didn't run the engine without coolant, or damage heads, the water pump and thermostat are fine -- it's just that I have to force the fan to come on when it needs to operate by turning A/C on.

I reviewed some threads in this forum, and someone else had my problem and everyone who responded to the guy acted like he was tripping because ALL e36's have mechanical fans. Well, that ain't so. There is no fan mounting on the water pump pulley. There is no mechanical radiator fan -- so it isn't a problem with the viscous fan clutch going bad. It's not that the auxiliary fan was removed -- there isn't and never was an auxiliary fan. Just an electrical fan attached to the radiator on the engine side.

MY QUERY: Bentley states that the fan is controlled by the engine control module. How do I troubleshoot and remedy the problem my car is having?

[witeshark]

Okay, the engine control module that switches that fan on by thermostat or temperature sensor is not working rightly. This is a fair guess since the A/C switch on forces that fan to start.

[talisman318is]

Which sensor(s) to evaluate? Where are they? And how to test? Any ideas?

[witeshark]

That could be complicated; the car manual or a dealer may need to help with this issue.

[jmo69]

There should be a sensor someplace. Check this thread, there should be something in the DIY about putting in a lower temp fan switch. That should give you some idea where it is. The Ultimate FDM (Fan Delete Mod) Thread - Bimmerforums - The Ultimate BMW Forum

[talisman318is]

Thanks for the ref to the FDM thread. 30+ pages of a lot of thoughts. So I guess I'll just get a new temp switch and see if that fixes the problem. Still don't know even if there is a relay. Does anyone have direct experience with a fan configuration like I described?