Trying to learn about relays

I have a digital multipmeter. I expose copper wire on the black & white wire going to the compressor. I check my ground to the battery pos side and it was good, there was no power going to the compressor. I check the fuses under the dash again and they were still good.

I then pull RDI Fan fuse 40A from the junction box and continuity was good.

I pull the relays to check the ohms. Fan 2 relay with 5 prongs, had three copper color prongs and two silver prongs. Only the silver prongs had ohms of 114.5. Fan 1 relay had two copper color prongs and two silver prongs, and silver prong ohms was 110.6. MIG/CLT relay was two copper and two silver and the ohms was on the silver prongs were 170.5.

I need a easier understanding on how to run 12 volts to the relays to test them.

Thanks for the help.

That is great, I will try it tomorrow and let you know what happen.

Thanks, getting closer.

I did the testing. Thanks for making it easier to understand. I did the 12v test to the three relays, all of them made a click sound. Fan 1 relay is for when the water temperature get hot and that work. I pull Fan1 relay out when the fan came on and fan shut down. I put the relay back in and fan came on.

With the relays out for Fan 2 and M/G CLT, I check terminals for power. The 5 terminal there is three across, the two outside terminal are silver and the one in the middle is copper. The one outside silver one had power only when the engine is on, I jump from one silver terminal to the other silver terminal and nothing happen. I tested the M/G CLT terminal and one silver and one copper terminal had power when engine was running , I jump the two and nothing happen. With the relays all put back in still no power to the compressor. Can I run 12v wire to the black & white wire that goes to the compressor.

I was tightening the hood latch when I drop the socket wench down by the front of the compressor. I start the engine and try turning the control nob for hot and cold, hot work but not the cold. But I notice on the dash red symbol, I look it up in the car book and it for the air bags and it just staying on. I know I didn’t do anything with the air bags. I remember seeing a black metal box with wires going into it where I drop the socket wench. I disconnect the battery and took two bolts off and got the metal box up to look at it. It was rusty, I disconnect the connect wires, there a plastic box inside the metal box, with two tiny terminal. I don’t know how to test this. On the menal box there a label saying Senor, Air Bag. FH. Toyota 89173-12100 187600-4990 Denso RH.

Thanks, I will check it out,

I finally got chance to 12v on the black & white wire going to the compressor and the clutch engage.

I went back to the relays and pull out M/G CLT relay that I tested before and heard a click. I hot wire again where the relay was this time touching more then one setup and the clutch engage. I bought a new relay , will put in tomorrow, it to hot and humid. Was $15.00 dollars for the M/G CLT relay. The air bag relay, my wrench mash the connector when it fell, will work on that after the A/C is working. Thanks for your help, learn a lot and now I have good cheat sheets to use and learn.

I bought a new M/C CLT for a/c magnetic clutch relay, clutch didn’t engage. Pull that relay out and hot wire and the clutch engage. Test the new relay it tested fine.

Then I went to Fan 2 relay pull it out and tested the terminals in the junction box this relay has 5 terminals. With the car running and a/c switch on, there was no power to the two silver terminals, but on the relay it self there continuity and ohms between the two silver terminals. There was power between one silver and one copper terminal. Between the two silver terminal is one copper terminal, with one silver terminal and the center copper terminal there power, switching to the other silver terminal there was power. If the two silver terminal on the relay tested with a click with 12v test, how will it work in the junction box with no power to the silver terminal.