QuestionQUESTION: my a/c works fine for about 10 minutes after starting then quits. If I shut it off for a few minutes and restart if will again work fine for a couple minutes and quit. It works ok at idle and only quits when I am driving. The system has been checked by a mechanic and he recommended a system evac and recharge and condenser cleaning but this does not seem to have fixed the problem. I am already in for over $300 and could really use some help
Joe
ANSWER: Joe,
By quit do you mean it shuts off and does not come back on until you turn the a/c switch off and then back on, or does it quit and kick back on by itself? (cycling) Do you by any chance have a way to check the pressures you are running? If so check them with the engine running about 1500 RPM. Also take them at idle and send them to me with the temperature of the outside air. That little bit of information can tell me alot.
If it doesn't come back on until you manually turn it off and on, that is in your electrical system and I recommend taking it to a reputable service shop, even, dare I say it , the dealer (shiver) for troubleshooting.
If it comes back on on it's own, I can help you there.
Inside your system you have 2 safety switches that shut down and protect your compressor. The first is a low pressure switch that disengages the compressor when the pressure gets too low. Low pressure could be caused by many things, the most often of which is a low refrigerant charge. That would be my first bet. As you are driving down the road, the compressor is turning faster, therefore it is pulling a lower pressure on your low side. That low pressure opens your low pressure switch and off goes the compressor. The mechanic that serviced it may have not fully charged it. Do you know whether he charged it by weight as a liquid or by pressures as a vapor? On a sticker in your engine compartment it indicates how much refrigerant your system requires. I always start from that point and then check my pressures, if they are not where they should be, I finish it charging as a vapor. He may have put the sticker weight in and called it a day. You can't do that though for the simple fact that every car that comes off of the assembly line has little differences.
It also may be that he charged it correctly but you have a leak in your system that has allowed some refrigerant to escape since you had the work done. How long ago was it in the shop? If it was within this past week, it would have to be a resaonable good sized leak and if the mechanic had pulled your system into a vaccuum as he should have, it would have been very noticable. If it has been a while, and he did not use a detection device then it may have slipped by him.
If the charge is correct the another source of low pressure would be a restriction in the refrigerant line somewhere. Usually occurs at the orifice tube (metering device) entering the evaporator. There is a small screen at the inlet of the orifice tube that is there to protect any particualtes from making it past. But this is a rather in depth replacement, so I would check and verify the pressures again. The paert itself is typicall between 20-50 bucks, but the labor can get you because everything they did before they have to do again as well as take your system apart.
The other switch is your high pressure switch that disengages the compressor during high pressure incidents. High pressure is usually caused by the condensor, in front of your radiator, getting filthy blocking air flow through it. I know the mechanic charged you for a cleaning and that urks me because all you have to do is take a regular garden hose and spray any dirt or whatever out of your fins. Even if it is not restricting airflow, I recommend doing this at the beginning of the year and about halfway through the hot season.
To check if your low pressure switch is what is causing your compressor to shut out is easy enough. First locate the switch, it is typically located on your accumulator (an aluminum container about the girth of a soda can with two lines running out the top of it) If it is not there, trace your low side line (has the smaller connector) until you find it. It will be somewhere in your engine compartment, you will not have to go into the cab. Disconnect this switch and with an insulated wire jump the connections inside the harness. Raise your engine RPMS to about 2200-2500 and leave it there for a minute or two. If it stays running, hook the connector back to the switch, raise the RPMs again, and watch the compressor. If it cycles on and off then it is a low pressure situation. 9 out of 10 times due to a low charge. But I have to say, DO NOT, DO NOT, DO NOT leave the switch bypassed for normal use. This will cause all types of expensive problems.
I hope I helped you out a little.
If you can send me the pressures and temperature, I may be able to help more. Thanks for the question.
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QUESTION: The a/c quits and will not come back on until I shut off the switch on the dash for a few minutes and turn it back on. I have already had the system checked for leaks and the condenser cleaned (along with a full diagnostic which showed normal pressures according to the mechanic).
AnswerSo that leads me to believe it is an electrical problem, and without knowing your wiring in particular, I can't do much for you. But again, I will tell a little.
Recently I worked on a Jeep Grand Cherokee which was doing somewhat the same thing, only it was the evaporator fan coming on and quitting. It wouldn't come back on until the system was turned off for about 15 minutes. The problem was in a relay. The relay had gone bad, and as the voltage was running through it it would work at first. But the longer it stayed on, it began to build heat up and opened the contacts. I replaced the relay, In this instance it was a dealer specific part, so it was rather costly, and it worked beautifully.
I would suggest checking your compressor clutch relay. Turn your A/C on and feel the relay casing after it runs a bit. A very small amount of heat is ok, normal due to electricity flowing through it, what you should not feel is more than about 5 degrees temperature difference in it. If you do, that is probably the culprit.
But again, I would recommend taking it to a reputable, possibly dealer, shop that has knowledge specifically on the echo. It may be something they have seen before and could be a common issue with that model.
I hope this helps a bit more, and sorry I cant be specific.
