New AC Condenser - Now Running Hot

[angusbn]

Replace the AC condenser and it's now blowing cold. Nice! However, while driving in the city with frequent spots, the coolant temp gauge shots up to the red zone and the coolant warning light comes on. Once on the highways, the coolant temp drops back to normal. This NEVER happened when the AC wasn't working.

I didn't check to see if the fan was operating - I don't believe it was.

Any ideas?

[Blitzkrieg Bob]

is running properly.

[angusbn]

How exactly do I do this?

[Macv]

Turn on the car, open your hood, and see if the fan in the front of the engine is spinning.

Sometimes if it's caught on something/broken (like with my e30 ) It'll cause you to overheat at a stop.

[colo525i]

Fan should be on low whenever the a/c is on and it will kick up to high speed in traffic. Mine had seized on my 525, just had to pull the front bumper and replace it.

[Guapo]

You can test it by pulling the temp sensor plug on the side of the radiator.

With the ignition on:

Shorting across violet/gray and ground should turn the fan on low.

Shorting across black/gray/yellow and brown should turn the fan on high.

If they do work as described, the temp sensor is bad in the radiator. If it does not, you'll have to check the relays. There is a writeup on the procedure on page 170-4 of the Bentley manual.

[Claude]

Replace the AC condenser and it's now blowing cold. Nice! However, while driving in the city with frequent spots, the coolant temp gauge shots up to the red zone and the coolant warning light comes on. Once on the highways, the coolant temp drops back to normal. This NEVER happened when the AC wasn't working.

I didn't check to see if the fan was operating - I don't believe it was.

Any ideas?

To replace the condenser you / they had to remove and reinstall the auxilliary fan (Big thin electrical fan that you can see through the grid over the bumper when in front of the car). I'll check first if it was reconnected properly, perhaps not (cable cut and/or associated resistor burned).

Without A/C activated the mecanical fan in between the motor and the radiator could keep the coolant temperature at it's normal level, but with A/C ON it's not enough, the auxilliary fan must than be ON either on low or high speed mode.

Worst case: your auxilliary fan motor is seized, you may check this trying to rotate the auxilliary fan blade manually through the grid through the bumper.

[bmwrp8]

Replace the AC condenser and it's now blowing cold. Nice! However, while driving in the city with frequent spots, the coolant temp gauge shots up to the red zone and the coolant warning light comes on. Once on the highways, the coolant temp drops back to normal. This NEVER happened when the AC wasn't working.

I didn't check to see if the fan was operating - I don't believe it was.

Any ideas?

might be the aux.fan check the fuse then check the fan itself...turn on AC then look if your E.Fan is working

[angusbn]

Checked aux. fan fuses 25/29 and they're OK.
The engine fan is working OK and engages once the engine is rolling.

Does turning on the AC immediately start the aux. fan so does it only engage when the temp raises towards the red zone? As it is it's NOT on when the AC is first turned on and temp is normal.

Is there a easy way to check the aux. fax sensor without removing the grill?

Anythings else to check?

[colo525i]

Check the connection to the fan to see that it isn't loose, mine has jiggled free. You can also jump the wires from the coolant temperature sensor on the radiator. It is on the right hand, outside on the radiator. Brown is ground, one wire is low speed one is high speed. If you jump this, you should hear a relay on the driver's side click, then the fan will spin. If the relays make noise but the fan doesn't spin, check the wiring. If the relays aren't making any noise, try checking them as well.