How to Solve BMW E90 Air Conditioner will not cool? Foxwell NT530 Helps?


BMW E90 car is parked outside and the inside temperature of the car is 120 or higher. The car blows hot air out the A/C no matter what I do to turn on the A/C. I can leave the A/C on, turn it off and back on, turn it to MAX, turn the temp down to minimum. I have tried everything. During this time the air blowing out the vents is very HOT. I put a thermometer in the vent and the temp is 110 to 120. It does not change very much for the next couple of minutes. I drive about two miles (three to four minutes) before the A/C starts to work. When the A/C comes on you can feel an instant temperature reduction in the air coming out the vent. In about five seconds you can feel the temperature drop significantly. It is like BMW has programmed the A/C to not work until the engine warms up.


How to troubleshoot?

Suggestion 1.

How old is your battery? If battery voltage is low, the car inhibits high electrical usage (HVAC) until the battery is charged a bit. I’ve noticed this a few times when car has been sitting an extended length of time.


If the battery is getting critically weak where the car might not start, the car will typically start complaining (Low voltage, excessive discharge).


Suggestion 2.

Have you had the system evacuated and recharged? That’s the first thing I do when diagnosing an AC issue. Simply checking pressures is not going to give you the full picture.


Suggestion 3.

Pop the hood start it up and have someone turn the A/C on and off and see if you can tell if the compressor is in fact kicking on.


Could be a number of things actually Bad compressor, bad condenser, or an issue with the blend door.


I’ve never had a condensor or compressor issue on a “newer” car, but the blend door has kicked my ass more than once.


What I did Next?

  1. I looked at the compressor to see if it is running. I don’t see a typical A/C clutch so it appears the compressor runs all the time.

I have done all my A/C work on my cars for the last 50 years. I put gauges on it and the pressure is fine. I did not pull a vacuum on the system and recharge it. That may be done in the future but not. The system works too good and works perfect except for this weird first 5 minutes on hot days after car sits for hours or days without running.

  1. I tried to register my battery with my Foxwell NT530 scanner. The foxwell program for battery registration sucks green turnips. My only choice was BMW battery or other. When I chose other. It said I needed to run the battery program in program. I don’t have program. I think I saw that you can register a battery in INPA. I will try that later.
    PS: I am glad to know that there is not an A/C clutch. I was thinking about running a 12 volt jumper wire to the A/C clutch to force the compressor on. I guess I won’t try that since there is no A/C clutch.3.

I am making a list of items to try based on three criteria. Cheap, fast, and most likely. I will do the free ones first. The first things on my list were to check to see if the compressor is running, check the freon pressures (also shows if compressor is running) and to try to register the battery. I will do the items that take more time and cost more later.

From what I know about BMW they way they make one thing dependent on something else being just right to work. I won’t be surprised to find out that my problem is caused because I replaced my battery and did not register the new battery.

I checked my a/c compressor and it does not have a clutch. It is always running. I checked my freon pressure and it is fine. I registered my battery. Now I have to drive the car a few times to see if that fixes the problem. This may take a while because I am retired and only drive somewhere a couple of times a week and I will have to drive it a few times to know if the problem is still there or fixed. Also since the problem only happens when the car sits for a few days and when it is miserable hot outside, I only get to check to see if it is fixed once or twice a week at the most.

What gets me about this is that I can predict within a few seconds when my a/c will start working. I am always driving by a the same house on the side of the road when the a/c starts cooling. The fan will be blowing hot air and you can instantly feel the difference when the a/c starts working.

I am making a list of all suggestions other BMW owners are giving me and will work down the list and do everything on the list until the problem is fixed. I am culling no suggestions. They will all be done until this problem is fixed.

I registered the battery using my Foxwell 510 elite. This did not ask me if I had a new AGM or lead acid battery and did not ask me what amp hour rating of the new battery. It just wanted to know if the battery was BMW or not. I will try to register the battery again with INPA later when I get INPA working on my laptop.


Alright. I drove my 335D today and the A/C was working as soon as I started it up. It is too early to say that registering the battery fixed it. But, it sure was nice having A/C from the get-go. It will take be a couple more weeks to be sure because I don’t drive it every day and it seems to only act up after the car sits a few days. I’ll let everyone know.

How to Solve BMW E90 Air Conditioner will not cool? Foxwell NT530 Helps?

Good to know:

So as a professional. My professional advice is to have the system serviced to check freon capacity…a system won’t work correctly without the right amount. Too little or too much. It doesn’t work correctly. Honestly, i stopped reading your response after you said you haven’t had it serviced.


Read Also:

Top BMW E90 battery registration tools advice


Best battery registration tool for home use -Foxwell NT510 (same as NT530 for E90)

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How to Solve BMW E90 Air Conditioner will not cool? Foxwell NT530 Helps?