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Re: ac stops blowing cold air after a few minutes
Take it to a second shop for another opinion. If the freon is low or too high it will affect the clutch. Let the second shop give you an opinion without telling them someone else looked at it. There are several pressure switches which can cause problems.
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I have had a similar problem quite a few years ago. You don't mention the model or year of your vehicle. It could be a relay that is on the firewall just below or behind the firewall in engine compartment in front of driver's side of the car. It took a really savvy MB mechanic an hour to locate and fix after 2 months in other shops, including an MB dealership. Mine was a 1988 560SEL that had that problem. After that was fixed, it worked perfectly for another 5 years - at which time I sold the car.
I hope this helps...
I'm sorry you have had such bad experiences with the shops. I would have stopped at the second one and forced them to fix it at their cost. I doubt you will be able to find the problem yourself, but I understand your hesitation to go back to another mechanic. I will be happy to try to walk you thru the diagnostic process but it may take a few days. First, do you know if the system is full of freon ? If it is full, do you know if the compressor is running when the ac is switched on ? The first shop should have discovered the blown fuse once they charged the system unless it took a day or two for the fuse to blow. The second shop that put the compressor on should have found the faulty fan, and the leaking hose if it is in fact leaking. So should have the third shop. If the compressor was faulty, and the system had been empty for a time, the hose could have started leaking once the system was being used. The pressure on the high side is over 200psi when the compressor is running. Let me know where you want to start with the diagnosis after you answer my questions.
Unplug the a/c compressor, there will be a plug near the pulley. Install a new fuse. Start the vehicle and turn the a/c on. Wait about the same amount of time it took for the fuse to blow in the past. Did the cues blow?
If no replace the a/c compressor, the clutch has gone bad.
If yes, than the wiring between the fuse and the relay or the relay to the comps sore is grounded. A careful inspection of the wiring should reveal the problem.
I would check the following possibilities: 1. Is compressor clutch working? - You need to do this when the ac is blowing hot air only - locate compressor drive pulley on engine - rubber belt wraps around it. Start engine and set to max ac. When the ac is blowing hot air, look at the center of the compressor drive pulley using a good flash light - watch it for a while, it should be spinning with the pulley - this means the compressor is engaged. If not, the compressor is not engaged. If your ac is blowing hot air, then the compressor should be engaged and running (trying to cool). If it is not engaged, then your compressor clutch is probably going out. Could be low voltage to clutch, but more likely the clutch is worn out and only working some of the time. Note: if working normally, the compressor clutch will engage and disengage in cycles- but the air should always be cold. If clutch is bad, compressor would need to be replaced (sold as one unit). This is tricky to diagnose and could take some time - you need to do it when ac is blowing hot air but set to max cooling.
2. Low on refrigerant or refrigerant has moisture in it? If your ac blows cold initially after being off for a while, then heats up, and continues to regularly cycle back and forth between hot and cool air, then the system may be low on refrigerant or the refrigerant may have moisture in it that is freezing and restricting refrigerant flow. An a/c shop can check refrigerant level and even replace refrigerant if moisture is suspected.
Could be other issues, but I would start with these.
well if the a/c has quit working .....the compressor probly finally failed....most times when the clutch hub begins to rattle or becomes real loose it has already worn the compressors snout....that cannot be fixed ...you need a new compressor .......
some reasons, low on refrigerant, compressor not activating , switch not sending power to ac clutch , no power to ac switch, leak in system , plugged ort restricted refrigerant flow in system, there are to many reasons to list all, have a qualified AC repair shop diagnose your problem could range from insignificant problem to a much more serious and costly repair...
it could be the air conditioning clutch going out. to check turn your car on and idle it with ac on and hood open. at the ac compressor it will have a pulley on it with a clutch that engages when the air conditioning is on. if it engages and disengages it can be the clutch itself has gone bad, the ac clutch will also disengage if there is not enough freon in the ac system, will also engage and disengage if the pressure gets too high in the ac system. Depending on the year of the vehicle it will disengage at full throttle and come back on when you are not at full throttle.
If it is a metallic sounding screech for example take a coke can and drag it across pavement kind of sound it could be a bad compressor or a bad ac clutch. If it is a more rubbery sound for example a car spinning its tires kind of noise it could be a loose belt.
1. Check to make sure all belts are tight under hood
2. start car and look at ac compressor to make sure compressor pulley is turning and that the fan clutch is engaged spinning