[alex sol]

After swapping out motor, my rad fan runs on high all the time. No if cold, warm, hot.

Does it have anything to do with no AC as I have not yet topped up the refrigerant?

Is there a faulty relay that is stuck open/closed?

No codes though coolant was low and i've since topped up and bled the system. Lots of heat in the cabin.

[BB_cuda]

in for the answer on this one. I have "sort of" the opposite problem. My fan will not run unless
1) AC is on and then it runs at max speed
2) AC off and idling in park for a long time. Fan comes on at a slow speed and cycles on and off between 95[off] and 97C[on]. When i drive normal, coolant stays fine at 80-81C. I'm not super worried as if it is hot out, i'm going to be running AC and then radiator will be cooled.

Before someone yells thermostat, that isn't it. The rad isn't being cooled so when T/S opens, rad will be at near same temp as the engine. If fan were running and still coolant was up high, i would agree T/S is stuck closed. Also, if T/S were stuck closed, driving would not cool it off [well maybe a bit].

[alex sol]

Just remembered I haven't connected the outside air temp sensor.

I did see other post about the fan only coming on with a/c.

Do we have thermostats that turn on at lower temps. I was going to buy one for my e36 m3 and sold it before I had the chance.

[RL18]

Have you checked your refrigerant? I'm not familiar with what temps a car ac runs at but overtime you may have had a pinhole leak or loose fitting and lost refrigerant overtime, this will affect how everything else runs (like the fan) since it runs based on those factory specs.

[alex sol]

thanks RL (ralph lauren) for the suggestion. My a/c is completely empty of r134a refrigerant due to the recent engine swap and have not refilled as i'm still sorting out some minor issues: transmission top up, coolant leak at the engine oil cooler, fixed a coolant leak at the transmission fluid cooler...

also forgot to install the heat shields under the car so exhaust coming out. mainly wanted to get the car running and see if any issues and will then button everything up...

[RL18]

Originally Posted by alex sol

thanks RL (ralph lauren) for the suggestion. My a/c is completely empty of r134a refrigerant due to the recent engine swap and have not refilled as i'm still sorting out some minor issues: transmission top up, coolant leak at the engine oil cooler, fixed a coolant leak at the transmission fluid cooler...

also forgot to install the heat shields under the car so exhaust coming out. mainly wanted to get the car running and see if any issues and will then button everything up...

Lol no problem . Bmw newtis actually has tutorials on how to evacuate it, refill it, and how much to weigh in. Seems pretty easy to me but that's if you have r134a available to you like I do.

I wonder if my vacuum pump, reclaim pump, and gauges would work on a car ac system. I'm sure special adapters would be needed though.