A/C commpressor relay not gettinng power
#1
06-25-2021, 11:22 AM
A/C commpressor relay not gettinng power
Hey! as the weather is turning hotter, i would like my A/C turned on, but the relay for the magnet cllutch won't turn on. I can force the relay on with a wire, so the MC thinnks the relay is on, and then the compressor works, and i gett cold air, but this is not a long term solution.
I have tested my relay, and it works.
i measured for volts over the relay when A/C is turned on vs off, and both measures to 0V. anyone have any advice?
I have tested my relay, and it works.
i measured for volts over the relay when A/C is turned on vs off, and both measures to 0V. anyone have any advice?
#2
06-25-2021, 01:58 PM
It would help to know what kind of car you're talking about. 1979 Accord? 2021 Accord?
There's usually pressure switches in the AC system that block the relay from being energized if the refrigerant is too low (or too high). The specifics vary a lot between those 2 years.
There's usually pressure switches in the AC system that block the relay from being energized if the refrigerant is too low (or too high). The specifics vary a lot between those 2 years.
#3
06-25-2021, 08:11 PM
It would help to know what kind of car you're talking about. 1979 Accord? 2021 Accord?
There's usually pressure switches in the AC system that block the relay from being energized if the refrigerant is too low (or too high). The specifics vary a lot between those 2 years.
There's usually pressure switches in the AC system that block the relay from being energized if the refrigerant is too low (or too high). The specifics vary a lot between those 2 years.
hope this helps
#4
06-25-2021, 09:39 PM
I'd suggest starting at the relay for some electrical testing.
How many pins are on the a/c relay? If there are 4 pins, two of the pins on the relay should be larger and better metal (like copper). The other 2 pins will be a cheaper alloy metal.
Hook your black lead on your volt meter to ground. Unplug the relay and start the car. Use the red volt meter lead to measure voltage on the relay box pins. One of the good metal and one of the cheap metal sockets in the fuse box should have 12V. Let us know what you find.
How many pins are on the a/c relay? If there are 4 pins, two of the pins on the relay should be larger and better metal (like copper). The other 2 pins will be a cheaper alloy metal.
Hook your black lead on your volt meter to ground. Unplug the relay and start the car. Use the red volt meter lead to measure voltage on the relay box pins. One of the good metal and one of the cheap metal sockets in the fuse box should have 12V. Let us know what you find.
#5
06-26-2021, 05:52 AM
I'd suggest starting at the relay for some electrical testing.
How many pins are on the a/c relay? If there are 4 pins, two of the pins on the relay should be larger and better metal (like copper). The other 2 pins will be a cheaper alloy metal.
Hook your black lead on your volt meter to ground. Unplug the relay and start the car. Use the red volt meter lead to measure voltage on the relay box pins. One of the good metal and one of the cheap metal sockets in the fuse box should have 12V. Let us know what you find.
How many pins are on the a/c relay? If there are 4 pins, two of the pins on the relay should be larger and better metal (like copper). The other 2 pins will be a cheaper alloy metal.
Hook your black lead on your volt meter to ground. Unplug the relay and start the car. Use the red volt meter lead to measure voltage on the relay box pins. One of the good metal and one of the cheap metal sockets in the fuse box should have 12V. Let us know what you find.
pin 4 side at 3V, and pin 3 side at 12V. if i remember right. i have tested the relay, and it closes when given power. was searching, and found this manual: https://cardiagn.com/hvac-08-10-accord/
at page 110 there is a climate troubleshooting page. how do i test if the condenser/radiator fans are Inoperative?
#6
06-26-2021, 08:01 AM
I'd suggest starting at the relay for some electrical testing.
How many pins are on the a/c relay? If there are 4 pins, two of the pins on the relay should be larger and better metal (like copper). The other 2 pins will be a cheaper alloy metal.
Hook your black lead on your volt meter to ground. Unplug the relay and start the car. Use the red volt meter lead to measure voltage on the relay box pins. One of the good metal and one of the cheap metal sockets in the fuse box should have 12V. Let us know what you find.
How many pins are on the a/c relay? If there are 4 pins, two of the pins on the relay should be larger and better metal (like copper). The other 2 pins will be a cheaper alloy metal.
Hook your black lead on your volt meter to ground. Unplug the relay and start the car. Use the red volt meter lead to measure voltage on the relay box pins. One of the good metal and one of the cheap metal sockets in the fuse box should have 12V. Let us know what you find.
#7
06-26-2021, 10:56 AM
To be thorough, what are you using for your volt meter ground when testing?
Is the 3V pin in the fuse box supplying power to the good metal (load side) of the relay or the cheap metal (control side) of the relay?
Is the 3V pin in the fuse box supplying power to the good metal (load side) of the relay or the cheap metal (control side) of the relay?
#8
06-26-2021, 03:20 PM
The link in post#5 looks like the legit shop manual for your car, so that is a very good reference for troubleshooting. Maybe hard to navigate that large book, until you learn your way around it.
#9
06-26-2021, 08:06 PM
i was measuring inside the fusebox, not on the relay. i also measured the voltage over the relay when a/c was turned on, and i measured 0V
#10
06-26-2021, 08:08 PM
yeah, i really struck gold :D as it looks now, it seems to be the pressure switch, but im not sure