QuestionQUESTION: The AC works and then stops. The mechanic recharged the system. When operating it blows cold air and then after 10 minutes or so the fan still blows but the air is no longer cold. What could cause this?
ANSWER: Mark,
there could be many causes of this. Can you answer a few questions for me please? Does this happen when the vehicle is in motion as well as standing still? Does it come back on by itself after it cuts out? If so, how long does it take to come back on?
With your description I am leaning towards your compressor clutch relay disengaging after it begins to heat up from the voltage traveling through it. (not supposed to heat up) Or your compressor clutch may be on the verge of failing, or your system is building high pressure and your high pressure switch is cutting off the compressor (this is a good thing)
If you can answer those questions for me, I may be able to narrow it down a bit more.
Thanks for your question and I await your follow-up.
---------- FOLLOW-UP ----------
QUESTION: David, first off thanks for the quick response. I don't know if it happens when it is standing still but certainly when it is moving. It takes about 20 minutes before it cuts out. It does not come back on by itself, only after it has set for several hours almost as if it has to cool down.
AnswerMark,
Ok, there are two directions in which I wm leaning on this. Your compressor clutch relay, or your compressor clutch itself. More towards the clutch itself.
First let's check the clutch relay. Locate the relay, it should be in your engine compartment relay box. After running the A/C until it cuts out, touch your relay and see if it feels hot. It shouldn't. If it does then that tells me that something is causing a serious draw through the circuit or your relay is going bad. As the relay heats up, the contacts inside it heat up. The heat may be making the metal contact bar flex and disengage the clutch until it cools back down. But it should not take several hours as you stated to cool that 1/8" wide piece of metal. So that leads me to believe more that the same thing is happening inside your clutch itself. Like the relay, the clutch is nothing more than a coil of wire. As the voltage passes through that coil a magnetic field is created snapping the clutch plate into the pulley itself. A by-product of a coil of wire and voltage is heat. I believe that your coil is heating up to the point it disengages itself until it cools down. And this, unlike the relay will take much longer to cool.
I really hate to be the bearer of bad news, but I recommend that you replace your compressor. Most new model compressors come with the clutch already attached, and many shops will not replace just the clutch on an old compressor. They can be finicky trying to set the air gap on them, and many shops just simply do not have the tools necessary for the removal. Ask around, maybe there is a shop in your area that replaces just the compressor clutch.
If it makes you feel better, you can try replacing the relay before undergoing this larger expense, the relay should run no more than about 10-20 bucks. But I am fairly certain it will continue to do the same thing. And the only component in the A/C system that will cause that large amount of draw is the compressor clutch itself.
I hope I was able to help you out a little, even if it was probably the last thing that you wanted to hear. If I can be of any more help, do not hesitates to ask. Thank you for the question.
