Vehicle - 1995 BMW 525tds Touring. German market car, so technical info here in the US is scant

Either way, before my ownership, the A/C compressor was replaced in 2021. Not sure if the magnetic clutch on the compressor was also replaced. Vehicle probably covered 5k miles since that time.

I started and drove the vehicle this weekend and the A/C was blowing ice cold immediately. ~5 minutes later, it started blowing lukewarm air. I checked the low-side pressure when I got home and it was certainly full, so no leaks.

What should I look at next? What do? I fancy myself a shade tree mechanic and want to troubleshoot this myself, but like all vehicle repairs I attempt I almost immediately get stuck...

Weird ass German car...  

But typically, if the charge is good and the air ain't blowing cold...  Its likely a weak / failing compressor.  Could be a problem with the ac clutch, or metering devise, or an air flow issue over the condenser....  But I'd be leaning hard towards a compressor on something that old.

If gauges look good, I'd be looking at something eletrical (HVAC control head) on that old of a vehicle.  Compressors normally come with the clutch.

Ice cold then not a few minutes later? Buckets of water out the bottom when you parked it then the AC worked again?

Evaporator is freezing up. Under or over charger, compressor or cycling properly, over pressure switch not functioning (doesn’t have one?), temp sensor acting up?

Usually under charge in my experience, or a module fault holding the compressor on 100%. It should cycle.

Compressor itself is 2.5 years old, I really hope it hasn't failed already.



This is a fear of mine, where do I start?



Zero condensation/water underneath the vehicle before, during or after.

I will add that the gauge I put on the low side read over 100psi, or rather, the needle swept as far around as it could. What does that mean? Is that too high? I've done nothing to the system since owning it (October'23) and its always works fine.

blend door could still be a problem.
look at the box and see if the actuators are working.
something that old may have vacuum leaks if they are pot driven vs electrical.
you can also check 2 ways.
see if any of the lines are cold. one should be if I recall correctly.
you could also crimp the heater core line, but I wouldn't do that unless you are prepared to replace it later.

I guess you could also temp gun the condenser and see if it is hot or feel it, but it might be hard to tell.

5 min of driving should bring you up to op temp. 5 min of idling probably not.
you could watch your temp gauge and see.
also see if it comes back cold when the car is cold.

What are your operating pressures. What’s temp of the refrigerant pipes going in and out of the evaporator

General rule of thumb is roughly ambient temp on high and low with the engine off. 70 outside, 70 psi high and low. Running high goes high, low goes low. Looking for 250 psi or so on the high side, fans come on or compressor cuts, high drops to 200, then back to 250, on and on. Low should drop to 40 or so and stay there, it will rise if the compressor cuts out.

Ambient temp under the hood might be more than the air, but not a whole lot more when you have the hood open and engine at idle.

That should get you close. Anything wildly outside that and you're off somewhere.

I guess that is an E34?  Yes those era diesels never came to North America but most of the AC system should be the same as the NA 525i gassers so you can get a pretty good idea looking in at the literature for those.

When you lose cold air, is the compressor clutch engaged?

Took the car to the shop that did the compressor job on 2021. He found the condenser inlet seal was bad. Bumper off job. I have cold a/c again