Okay, AC gurus give me your thoughts.
Took the car into the dealer, dealer ran diagnostics - 'nothing wrong, just needs a charge'. Kay, charge it.

Now when I drive, car starts up, A/C is cold, drive for about five minutes and A/C stops blowing cold and just blows warm, drive some more, cold air comes back, drive some more, no cold. You get the picture. Fan speed doesn't change, just air temp.

Maybe just the A/C - Heater control unit has gone bad??


Any thoughts?

2004 Justacooper with auto A/c

 

What were the symptoms the original time you brought it into the dealer?

Does the green light on the A/C button go out or blink at any point during the situation?

Does it only blow cold when you're driving and then go hot perhaps at stops?


Without a fault I would not jump on the a/c control unit. I would suspect perhaps either insufficient airflow from the radiator fan causing the condenser not to cool which would build up excessive pressure in the high side line causing the system to kick off. Or, insufficient airflow or overcharged A/C system or blockage in the expansion valve and/or evaporator causing a line or the evaporator to freeze up- thus causing the system to shut down temporarily until it thaws and then restarts the process.


Proper gauge readings will be able to identify if the system is overfilled. IF so then it needs to be recharged with the correct fill.

If not then they need to read the gauges with the system running and watch for either the high side pressure to go too high (condenser overheating) or watch the low side to go too low then raise back up (frozen expansion valve or blockage causing freeze over).

Take it back and get further diagnosis.


and Again, what was the original symptom you brought it in with?

 

What were the symptoms the original time you brought it into the dealer? Same as described above (cold air some of the time, warm air others)

Does the green light on the A/C button go out or blink at any point during the situation? (No)

Does it only blow cold when you're driving and then go hot perhaps at stops? (No, movement doesn't seem to make any difference)


I ran down and did the code check and got a FF 00

As a whim, i put the key in the second position and turned on the A/C, only warm air, no cold. Started the car and got ice cold a/c air.

 

To be honest I don't recall what that code means.

Also, without the engine running you will never get cold air, so that explains that last bit. Engine running = compressor spinning = refrigerant cycling through the system = cold air.

Like I said before, I suspect perhaps either insufficient cooling overheating the condenser, or blockage that is causing the low side to freeze over.


I can't help you with what FF 00 stands for though..

 

I would bring it to an a/c shop....
What can happen is the system could have too much oil....often from folks topping off the system with the r134a/oil combo cans, or perhaps the system was opened up for work, the dryer not replaces, no vacume pulled, and then simple refilled...results ...air/134a/moisture mix is not a good combo...moisture can freeze in the expansion valve....
A goo ac shop will have a machine, and will know as soon as they plug in if the system is contaminated......

 

Thanks for the feedback.


As an FYI the code is MINI computer speak for 'nothing is wrong'.

 

Also check the relays in the fuse panel under the bonnet. I had the very same issue (intermittent cold/warm air) on my '05 MCS and the relay had popped out of the socket. Tight suspension and rough Cali freeways will do that! I put some insulating foam over the relays before putting the cover back on to keep the relays in place. All is good! Cost=$0.

 

Thanks for the idea, but checked and they are all snug in their spots.

 

Any solution to this issue? My '02 R53 has had similar issue's as well as getting very close to over-heating while running a/c when I come to a stop or get caught in bumper to bumper traffic. I have noticed that with mine the fan will cycle fine until I come to a stop causing high heat and then the entire fan cooling system will cut out completely (neither high or low) until I get rolling again and not use the a/c until normal operating temp is achieved again.

 

I have same issue w/ my 05. blows cold, then warm for a minute of so, then cold again. The system has never been tampered with. I had Auto zone guy check today for low coolant, he said i was in the green, so I passed on purchase of do it your self charging canister and valve. Help please.