Oldtee

The fan comes on after the AC has been running but when turned off. (ie) Shark at idle, AC off and the fan is running. From the schematic power is on the Aux Sensor relay (AC Engine Fan?) and is looking for a ground to close. It can find one from one of three places. Oil temp switch at the torque converter, the thermoswitch cooling water (switch?) or the temperature regulator freon (switch?). It can also get power from the thermo switch intake pipe via the preresistance aux fan (resister), where-ever that is.

What am I missing?

j.kenzie@sbcglobal.net

Before I wired my fan for full-time on with AC on, it hardly ever seemed to come on. I hear the freon temp switch doesn't work that well. If you jumper the two leads going to the freon switch with ignition on the fan should run. It is a simple grounding switch. With an add-on relay you can take a 12V trigger from the AC clutch wire and close the relay to activate fan. I posted a diagram a few weeks ago. I think it's an improvement in hot weather especially with R134, if your alternator can handle the load (it should).

Alan

So whats the problem? The fan may need to run for any of: the AC, the oil temp or the engine (coolant) temp. Are you saying that none of these could be demanding it (say you just started the car briefly and it never got hot)?

Its normal for the fan to run on a while when the car is hot - even with the engine off & key out..

Alan

Oldtee

You hit the objective, which is to figure out how it is supposed to work, each and every time. Since there is no computer involved it should be simple. Testing is going to be difficult unless you know at what temps the various switches kick off. Otherwise I guess I could just replace all the parts and hope for the best.

The owners manual says " The air conditioner condenser fan is electrically driven. It is switched on automatically by a thermostat when the coolant reaches 92F Even when the engine is turned off the fan will continue running, until the coolant tempature has dropped to 87F and until the engine itself has cooled down sufficently." Then a warning; don't put your pinkie in the fan if you want to keep your fingernail.

zoltan944

i suggest, rewiring it to turn on when the AC kicks on and stays on the whole time the AC is on. I know the car wants to get up to operating temp, but if you car has been sitting in the sun and its not to operating temp, it takes a long time to get it cool in there with your condensor not having a fan on. Unleess of course you are driving over 30ish, then the air pushes through there nicely!

justin

Where is this wiring diagram?

Oldtee

Workshop manuals. A must if you are going to do anything yourself.

j.kenzie@sbcglobal.net

[QUOTE=zoltan944]i suggest, rewiring it to turn on when the AC kicks on and stays on the whole time the AC is on. I know the car wants to get up to operating temp, but if you car has been sitting in the sun and its not to operating temp, it takes a long time to get it cool in there with your condensor not having a fan on. Unleess of course you are driving over 30ish, then the air pushes through there nicely![/QUOTE
I understand your curiosity but, I'm not so sure why you really need to know what the car was designed for with R12, German climate, 1980. You can purchase new switches to replace any nonfunctioning or you can assume that with AC on it's a hot day, your car will come up to temp quickly, and dissipating the AC condensor's heat can only be a good thing. My freon switch is disconnected. I don't care about my coolant or transmission temp sensors because on a hot day I've manually activated my fan by turning on my AC. My alternator handles the load with blower, lights and AC on so I'm satisfied so far.
YMMV

dr bob

The freon temp switch looks at the high-side frean after the condenser but befgore the drier. If the freon there is still hot, the fan will run to cool it. Same with engine coolant and the ATF temp-- Too hot and the fans come on. I'm not 100% sure that the pre-S4 cars have the intake temperature switch though.

The popular suggestion is to wire a relay to run the fans whenever the compressor is running. I'm not sure that it's necessary --IF-- your AC is charged correctly. The fan will be slow to start when the system is slow to cool, not vice-versa. When things are charged and working correctly, the fan will start within a minute of switching the AC on in warm weather. In cold weather, you don't need the fan until the (un)condensed freon is hot anyway. There's a psychological advantage to having the fan come on instantly, though.

Oldtee

Dont you just hate it when someone uses logic and reason!