E34 coolant leak

[Kamz e34]

Hello everyoneo
I recognied my e34 525i m20b25 after a drive with ac on i find under the car a bit of blue coolant and water when i park the car. I know that the ac cause water only. What about the coolant? The car every month i should add less than 0.5l of coolant. Is there any leak or something wrong or it's normal to see coolant with water under the car after a drive with ac on?

[shogun]

if you have to add every month coolant, then you have a coolant leak. As the volume is low, easiest to find the leak is a pressure test, https://blog.1aauto.com/how-to-perfo...pressure-test/
The test requires connecting the pressure tester to the coolant reservoir or the radiator and pumping the tester to pressurize the system, which can help find coolant leaks. These steps explain how to use a coolant pressure tester and perform a coolant or radiator pressure test.

[Kamz e34]

Three weeks ago i took the car to the shop and we tested everything and we made a pressure test and nothing appeard. It's only when the ac is on after a long drive i can see blue coolant with water of the ac. I know that it's normal to have water because of the ac but is it normal to see blue coolant with the water? I tried seeing under the car and i saw that the leak is coming from the middle where the transmission is located. In the pressure test everything was perfect and the car runs exellent. I drove it 600km in the last 3 weeks (highways and mountains) with ac on and she drive perfectly and smoothly but now i should add 200-300ml of coolant to get to the level max. And everything is new on the car (radiator, thermostat, fan clutch, coolant is new, hoses...). I only see blue coolant under the car after a ride with AC ON only.

[shogun]

if you can see blue coolant under the car where the transmission is located, then it could be you have a leak in the heater core or the connections, at the bottom of the AC the moisture/water/coolant is collected and there are 2 drain holes to under the car.
Check these items https://www.bimmerforums.com/forum/s...(IHKA-content)

Basically you have to check from heater valve thru the firewall to interior all parts http://bmwfans.info/parts-catalog/E3..._conditioning/

when AC is on, thru these drain holes normally the moist is draining, that is why you see on cars with AC on usually some clear water dripping from the AC system, but when in your case the color is blue, then it is leaking coolant from the heater/AC system behind the center console. Maybe just an O-ring leaking, you have to check it.