I have a 1991 corvette the a/c compressor wont run unless i apply 12 volts direct to it i jumped out the high pressure switch. Is it controlled by an ecm? What are some other things i can try?
yES I HAVE A GOOD CHARGE ITS AN ELECTRICAL PROBLEM. I meant to say i jumpered the high pressure switch and there was no change so i dont believe that to be the problem
yES I HAVE A GOOD CHARGE ITS AN ELECTRICAL PROBLEM. I meant to say i jumpered the high pressure switch and there was no change so i dont believe that to be the problem
sure i'll work with ya, I dont mind paying i wish the chat window was working so i could pick someones brain. Dont know how to fix that either lolsure i'll work with ya, I dont mind paying i wish the chat window was working so i could pick someones brain. Dont know how to fix that either lol
Im not sure which relay it is that i should be looking at? Do you have any idea as the location the colors of the wires that are coming from this relay? i can run the test on the relay if you tell me what to doIm not sure which relay it is that i should be looking at? Do you have any idea as the location the colors of the wires that are coming from this relay? i can run the test on the relay if you tell me what to do
okay its the relay by the evaporator under the hood. I started the car and turned the a/c control from the off to max a/c position and it clicks everytime on and off. So doesnt that tell me the relay is switching? still no compressor operation. Another thing i left out is the plug for the a/c fell apart it had a small resistor in the plastic housing of the plug could that prevent it from coming on? I dont suspect that because like i said earlier if i apply 12 volts direct to the compressor the clutch engages and the system works.okay its the relay by the evaporator under the hood. I started the car and turned the a/c control from the off to max a/c position and it clicks everytime on and off. So doesnt that tell me the relay is switching? still no compressor operation. Another thing i left out is the plug for the a/c fell apart it had a small resistor in the plastic housing of the plug could that prevent it from coming on? I dont suspect that because like i said earlier if i apply 12 volts direct to the compressor the clutch engages and the system works.
no im not sure if its a capacitor or a resistor this may be my problem how can i be sure? and do you know what power should be going into the relay i have a red, blue, orange , purple and black wire coming out of the relayno im not sure if its a capacitor or a resistor this may be my problem how can i be sure? and do you know what power should be going into the relay i have a red, blue, orange , purple and black wire coming out of the relay
same problem here. 1991 corvette put direct 12v to compressor. works fine. last night replaced pressure cycling switch. finally found all existing 5 prong relays. tested all and they seem to be in good working order. few of them contacts are black but all five tested good. will be putting them back in tonight. but im sure the compressor will not be clicking on :( any ideas??
johnnysame problem here. 1991 corvette put direct 12v to compressor. works fine. last night replaced pressure cycling switch. finally found all existing 5 prong relays. tested all and they seem to be in good working order. few of them contacts are black but all five tested good. will be putting them back in tonight. but im sure the compressor will not be clicking on :( any ideas??
p.s. i understand if freon is low the compressor will not kick on. but if there is no power to compressor it also will not engauge.. what am i missing
johnny p.s. i understand if freon is low the compressor will not kick on. but if there is no power to compressor it also will not engauge.. what am i missing
- determine which relay leads are the switch contacts
- apply 12 volt to the coil leads
- put a multimeter on the switch leads (set to ohms)
- if relay is good, you will get a 0-ohms reading thru the relay switch leads
- if relay is bad, you'll get an infininte-ohms reading ("overload"), or you'll get a very high reading, like millions of ohmsTesting the relay (I said this was involved):
- remove relay
- look at the schematic on the relay
- determine which relay leads energize the coil
- determine which relay leads are the switch contacts
- apply 12 volt to the coil leads
- put a multimeter on the switch leads (set to ohms)
- if relay is good, you will get a 0-ohms reading thru the relay switch leads
- if relay is bad, you'll get an infininte-ohms reading ("overload"), or you'll get a very high reading, like millions of ohms
First, just because a relay is clicking doesn't mean it's closing an electrical circuit -- they almost always click -- this means the coil is working -- does not mean the contacts are good -- for relays to work, the coil/solenoid has to work, and the contacts have to be making good electrical contact.
Secondly, yes, if there is a broken/loosely-connected resistor in the plug it will open the circuit and prevent current from going to the compressor. Are you sure it's a resistor, or maybe a capacitor?First, just because a relay is clicking doesn't mean it's closing an electrical circuit -- they almost always click -- this means the coil is working -- does not mean the contacts are good -- for relays to work, the coil/solenoid has to work, and the contacts have to be making good electrical contact.
Secondly, yes, if there is a broken/loosely-connected resistor in the plug it will open the circuit and prevent current from going to the compressor. Are you sure it's a resistor, or maybe a capacitor?
The relay should be very near the compressor. Wire colors, I have no idea. When the A/C is turned on the relay should click -- you will probably need someone inside the car turning the A/C on and off while you listen for the click.
There couldn't be that many relays near the compressor -- do you see anything which looks like a relay?The relay should be very near the compressor. Wire colors, I have no idea. When the A/C is turned on the relay should click -- you will probably need someone inside the car turning the A/C on and off while you listen for the click.
There couldn't be that many relays near the compressor -- do you see anything which looks like a relay?
First, I don't think this A/C system is controlled by a computer.
Since your info is in two postings, I'm getting kinda lost here.
I think you mentioned a relay clicking. There is definitely a compressor relay. It could be that relay is faulty.
Can you locate that relay? If you can, maybe try tapping it to see if it's stuck, and the tap will free it. If that doesn't work, it may be burned contacts in the relay. There is a way to test the relay, but it's very involved.
If you don't want to test it, may be a good idea just to replace it.
If you can do what I suggest, and get back to me, before you buy any parts, we can discuss next steps.
Charlie
First, I don't think this A/C system is controlled by a computer.
Since your info is in two postings, I'm getting kinda lost here.
I think you mentioned a relay clicking. There is definitely a compressor relay. It could be that relay is faulty.
Can you locate that relay? If you can, maybe try tapping it to see if it's stuck, and the tap will free it. If that doesn't work, it may be burned contacts in the relay. There is a way to test the relay, but it's very involved.
If you don't want to test it, may be a good idea just to replace it.
If you can do what I suggest, and get back to me, before you buy any parts, we can discuss next steps.
I see you have reposted this problem -- neither of your postings is showing that this is a "paid problem". There is definitely a glitch somewhere -- it' s shown as a "free problem".
If you'll work with us on this maybe we can find a solution -- paid or not.
Sorry for the inconvenience.
Charlie
I see you have reposted this problem -- neither of your postings is showing that this is a "paid problem". There is definitely a glitch somewhere -- it' s shown as a "free problem".
If you'll work with us on this maybe we can find a solution -- paid or not.
Well, if you jumped out the high pressure switch to get the compressor to run, it sounds like the high pressure switch is open because there is no pressure in the system.
Have you checked the refrigerant charge?Well, if you jumped out the high pressure switch to get the compressor to run, it sounds like the high pressure switch is open because there is no pressure in the system.
Have you checked the refrigerant charge?
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If you are jumping the A/C clutch with a separate power supply there are 2 cut off switches in the system. They are used to protect the system and work with either high or low pressure.
You need to pressure test the system, idle engine speed, and bypass the low pressure cutoff to see what the readings are.
Sometimes the low pressure switch will get weak and work too early. It can be changed without losing much Freon. Put a wire loop in the harness connector after removing the harness from the switch and bypass it with the engine running. Do not let the wire loop operate withut the engine running.
There are a variety of Freon mix products to chose from. Something with a sealer and conditioner would probably be good.
As for the pressure, moderation is best. You want the compressor to run the longest for the best cooling. So a charge maintaining a pressure midway between the 2 pressure switches will work best.
If you have applied 12 volts to the system some other way, I can not imagine what was done.
the AC compressor has a "shutdown switch" when not enough refrigerant is in the system run a wire from the
run a wire from the + battery cable to the compressor pulley switch with the engine running, ac on if the compressor clucth engages (turns) you have low refrigerant charge
the high pressure switch kicks the compressor off when the pressure rises, the low pressure switch kicks it on, check that switch, unplug the wire and use a continuity meter to see if the switch functions, also check for power getting to the plug itself
Just bought my vette last Sept. had a similar problem. the AC would work for a while and then shut off. ad a loose plug connecter at the compresser. tried to get a new plug but it is a part of the wireing harness. got a couple of spade clips. cut off the old plug and connected it with the spade clips. end of problem hope this helps. I am not a mechanic just a "tinkerer"
This could be a few things. The freon could be low, one of the switches (high or low pressure) could be bad, or you could have a bad compressor clutch. You can test the clutch by checking for battery voltage and ground at the two pin connector with the A/C on if you have both power and ground, then the clutch is bad. You really should start by hooking up pressure gauges to the A/C ports to check the pressures, and these vary depending on ambient temperature and whether the A/C compressor is engaged or not. I am willing to bet that the freon is low though and may be just as simple as recharging the system.
Hope this helps. Good luck!
check the low side switch located on the ac receiver drier for 12 volts if so jump it with a paper clip if the compressor comes on then the relay is good if not the relay is in the fuse junction box under the hood.Most likely the pressure sensor.
That little component is a flyback diode. It is critical in preventing high voltage from damaging the relay. When you turn the current off to a large inductive load like a compressor clutch, a very strong high voltage spike is generated and it arcs across the relay contacts destroying them, also potentially jumping into the very sensitive control circuit from the ECM. That diode must be replaced and it must be installed in the right direction or it will fry. You can get them at any electronics supply store, ask for a 1N4001 diode. This system is not that hard to diagnose, but I think at this point, you would be best served to find someone with a scan tool and check to see if you're getting that request signal, and tracing it back from there. Please! replace that diode first or you will just keep melting parts. If there is anything else you need let me know.
yES I HAVE A GOOD CHARGE ITS AN ELECTRICAL PROBLEM. I meant to say i jumpered the high pressure switch and there was no change so i dont believe that to be the problem
sure i'll work with ya, I dont mind paying i wish the chat window was working so i could pick someones brain. Dont know how to fix that either lol
Im not sure which relay it is that i should be looking at? Do you have any idea as the location the colors of the wires that are coming from this relay? i can run the test on the relay if you tell me what to do
okay its the relay by the evaporator under the hood. I started the car and turned the a/c control from the off to max a/c position and it clicks everytime on and off. So doesnt that tell me the relay is switching? still no compressor operation. Another thing i left out is the plug for the a/c fell apart it had a small resistor in the plastic housing of the plug could that prevent it from coming on? I dont suspect that because like i said earlier if i apply 12 volts direct to the compressor the clutch engages and the system works.
no im not sure if its a capacitor or a resistor this may be my problem how can i be sure? and do you know what power should be going into the relay i have a red, blue, orange , purple and black wire coming out of the relay
same problem here. 1991 corvette put direct 12v to compressor. works fine. last night replaced pressure cycling switch. finally found all existing 5 prong relays. tested all and they seem to be in good working order. few of them contacts are black but all five tested good. will be putting them back in tonight. but im sure the compressor will not be clicking on :( any ideas??
johnny
p.s.
i understand if freon is low the compressor will not kick on. but if there is no power to compressor it also will not engauge.. what am i missing
johnny
Testing the relay (I said this was involved):
- remove relay
- look at the schematic on the relay
- determine which relay leads energize the coil
- determine which relay leads are the switch contacts
- apply 12 volt to the coil leads
- put a multimeter on the switch leads (set to ohms)
- if relay is good, you will get a 0-ohms reading thru the relay switch leads
- if relay is bad, you'll get an infininte-ohms reading ("overload"), or you'll get a very high reading, like millions of ohms
First, just because a relay is clicking doesn't mean it's closing an electrical circuit -- they almost always click -- this means the coil is working -- does not mean the contacts are good -- for relays to work, the coil/solenoid has to work, and the contacts have to be making good electrical contact.
Secondly, yes, if there is a broken/loosely-connected resistor in the plug it will open the circuit and prevent current from going to the compressor. Are you sure it's a resistor, or maybe a capacitor?
The relay should be very near the compressor. Wire colors, I have no idea. When the A/C is turned on the relay should click -- you will probably need someone inside the car turning the A/C on and off while you listen for the click.
There couldn't be that many relays near the compressor -- do you see anything which looks like a relay?
First, I don't think this A/C system is controlled by a computer.
Since your info is in two postings, I'm getting kinda lost here.
I think you mentioned a relay clicking. There is definitely a compressor relay. It could be that relay is faulty.
Can you locate that relay? If you can, maybe try tapping it to see if it's stuck, and the tap will free it. If that doesn't work, it may be burned contacts in the relay. There is a way to test the relay, but it's very involved.
If you don't want to test it, may be a good idea just to replace it.
If you can do what I suggest, and get back to me, before you buy any parts, we can discuss next steps.
Charlie
I see you have reposted this problem -- neither of your postings is showing that this is a "paid problem". There is definitely a glitch somewhere -- it' s shown as a "free problem".
If you'll work with us on this maybe we can find a solution -- paid or not.
Sorry for the inconvenience.
Charlie
Well, if you jumped out the high pressure switch to get the compressor to run, it sounds like the high pressure switch is open because there is no pressure in the system.
Have you checked the refrigerant charge?
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