318ti Cooling Fan HELP!!

[ti guy]

Hi, I am new to the threads and this is my first post so let me know if I need to improve anywhere!

Anyways, I have a 1996 318ti with about 210,000 miles. I bought it a couple years ago with the ac not working, and it would overheat when sitting at idle for a while (it rarely happened because I was never sitting at idle long enough and if it did, I would turn the car off right away). It wasn't a problem until it was my daily it so I wanted to fix the ac for the hot summer months. I started off by replacing the outside temp sensor (I was getting a -40ºF reading), the compressor, the dryer, and they radiator fan. The ac was working fine for a couple of weeks after I got it filled with refrigerant, then it just started blowing warm air like it used to. The cooling fan would not turn on either when the ac is on or if it starts to overheat. I have seen many threads that say when the ac is on the fan works but mine does not.

Here's what's really stumping me... I have read all of the forums and I have done every test I can. I started off by checking the fuses and relays with a multimeter and even replaced all of these. Next, I tried to hook the fan straight up to a 12v battery to make sure it was working, and sure enough it spins right up. I read that if you unplug the coolant temp. switch and jumper 2 out of the 3 terminals the fan should turn on if the switch does not work with a high speed, the other terminal is for the low speed. I did this and just tested each combination of terminals because I wasn't sure which was ground, or high speed, or low speed. The fan would turn on with the jumper in the ground and in one of the other 2 terminals (I'm not sure if it was the high speed or low speed) I could hear a relay click when I jumped the other terminals but the fan did not turn on. I replaced this switch anyways to no avail. So currently my coolant fan will not turn on when it starts to overheat and the new ac compressor will not engage anymore.

I can't find any other problems there could be. The new fan 100% works, brand new coolant temp. switch (proper coolant flush when this was replaced), fuses and relays work, it can't be wiring to the fan because it would turn on when doing the jumper test on the coolant temp. switch wire harness. Any ideas would be help a lot!

[AKBO]

How is your Thermostat and water pump?

[ti guy]

I’m just ordered a thermostat and the 2 relays which I will replace asap.

[AKBO]

If you found that fan didn't run when you jumped one terminal, may be the fan itself. Check it first before replacing anything. If the fan works when you put on the AC, and it doesn't work when you jump the other terminal it seems the problem is the fan.

[ti guy]

Well I replaced the whole fan assembly and with the old one, I connected it straight to a 12v source on both of the terminals and it worked. I decided to do the same test on the new fan and it worked at both speeds when connected to the 12v. I was testing the coolant temp. switch when it only spun up on one speed, that’s what lead me to believe that was the culprit but I replaced that switch and nothing changed. So knowing this we didn’t even have to replace the fan.

[AKBO]

Is it OK now?

[runnr548]

How is it running now?