QuestionQUESTION: the clutch wont kick on at all. Any ideas?
ANSWER: Stephanie,
There are several things that will prevent your clutch from engaging. I will start with the easiest, and then ammore than willing to work with you from there to figure it out through sending me a followup. But please send me what type of vehicle we are talking about, and a pressure reading if you have it.
If you have already checked the fuse for your A/C clutch...
The most common reason for the clutch to not engage is a low refrigerant charge. Inside your system is a low pressure switch. This switch is there for the sole purpose of preventing your compressor from operating when there is a low pressure state. Protecting it from burning itself out. Low or no refrigerant = low or no pressure.
I'm not sure what type of vehicle I am going off of here, but I will give you the basic scheme for finding and checking it. From your compressor there are two lines. Or if you know where the low pressure service port is on your vehicle, this would be a better place to start. Trace that line until you find a switch hooked directly into the line. Or it may also be mounted on your accumulator, if your vehicle has one. (An aluminum canister, about the girth of a soda can, with two hard lines coming from the TOP of it) Once you locate this switch, disconnect the plug from it. With the key in the run position (engine on or off-but easier to hear the nest step with it off). turn your A/C switch and fan speed switch on. With an insulated wire jump one terminal in the wiring harness plug to the other. You should hear a "snap" as the clutch kicks in. If you do, chances are you have a leak that has created a low refrigerant charge. You would need to have the leak found and repaired and have the system charged back up.
If you do not, that could be either direction in the harness, and you will need a multimeter or voltmeter before I talk you through the checks. Try this method first and let me know what happens.
Thank you for the question, and if you need more, please let me know with a followup on this question.
Thank you for the question, and good luck.
---------- FOLLOW-UP ----------
QUESTION: Thank you for replying sorry it has taken so long for me to write back. The van is a 1997 Dodge Grand Caravan. We done everything you said to try, but still didn't work. The system is full and still the compressor doesn't kick on. I don't want to spend a bunch of money at a shop to fix it. Thank You for your help and what else shoul i do?
AnswerStephanie,
I was really hoping that my last answer would do it up for you. Ok, ready to do some reading? This may be a long one. LOL.
You will need a multimeter to do these checks. If you don't have one, one can be picked up at any autoparts store relatively cheap.
The first check I want you to make is at your A/C clutch fuse. You said the fuse is good. Now check it for voltage. You should have 12 volts on the input side of the fuse.
>> No voltage? There is a break in the line somewhere prior to it coming into your fuse box.
>>>>12V? Good.
With the key in the run position... engine off, and the A/C switch on....
The next check is your compressor clutch relay. You should read 12V at one of the coil contacts of the socket the relay plugs into.
>> No voltage? Turn off the power and do a continuity check between the relay coil sockets and the A/C clutch fuse. You should read resistance. If you do not, there is a break in this wire that needs replaced. If you do read resistance...
check your thermostat (mounted on your evaporator housing) for continuity. You should read resistance between the terminals with the wires unplugged from it. If you read OL or no resistance, replace your thermostat as it is staying open when it should be closed.
>>>> 12V on one of the socket connectors? Good. On the relay itself there should be a diagram dran on the side of it. Between the contacts connected by what looks like a spring (this is your coil) you should read resistance. If you do not this means your relay coil is burnt, replace the relay. If you do...
Check the other socket terminals. (Not the ones the coil contacts go into) One of the two should have 12 volts to it. With a jumper wire connect these two terminals. Did you hear your clutch engage?
>> Yes? Replace your relay, the contacts inside it are not making connection.
>>> No? plug your relay back into the socket.
Next check is your low pressure switch. Unplug the harness plug from the switch. Check both wires for voltage. You should read 12volts on one of them.
>>> no voltage? You have a break in the line between your relay contacts and your low pressure switch plug that needs to be repaired.
>>> 12V? Good. Use a jumper wire to jump the terminals in the plug. You said you already tried this and the clutch did not engage, right? so we move on... But if this did work this time, check your refrigerant charge again, if it is good, replace your low pressure switch. If it is low... charge it up.
Our next stop is your high pressure switch. This is somewhere on your high side line. It will have four wires coming from the plug. Check these wires for 12V. Two of them should have it.
>>>12V? Jump these 2 wires to the other two. One hookup will turn on your condensor fan, the other hookup should engage your clutch. If it did... replace your high pressure switch. If it did not...
Next and last is your compressor clutch itself. Check your harness plug for voltage. One should read 12 V.
>>> no voltage? do a continuity check between your compressor plug wires and your high pressure switch. You should read continuity in one of the high pressure switch wires to your compressor plug wires. If you do not, you have a break in this wire that needs to be repaired.
>>> 12V on one of your harness plug wires? Then do a continuity check between the other compressor plug wire and ground. You may have a bad ground that needs to be tightened or have the corrosion cleaned from it.
>>>>>>>>>>>>>> 12V on one wire, and the other one is saying you have a good ground? Bad news... replace your clutch/compressor.
OK, that is the rundown on the electrical checks. I tried to make them as easy or understandable as I could, but if I need to clarify better... let me know on what part you didn't understand and I will try to break it down some more. Congratulations though... this is the longest response to a question I have received yet. :) lol
I hope I was of some help, If I was, please remember to rate this answer.If I can do anything more for you now or in the future, please let me know. Thank you for the question and good luck in everything.
