I am sorry I did not make it clear about the chart. The chart represents the AC system without the compressor running. The high pressure side and low side pressure will become the same value after the compressor has stopped running for a few minutes. The chart represents that condition. Your 70 psi pressure reading at 58° F is a bit higher than the chart shows, but that is not a problem. There are too many variables for you to expect an exact match with the chart. Also, the 70 psi reading is well below the cutout point of the high pressure switch. That switch comes into operation when the high pressure gets above 350 psi or higher to protect the system.
If it was a 90° F day, you would expect to see a pressure of around 104 psi without the compressor running (see chart). Obviously, in a normally operating system the compressor would still activate if AC was selected. This is why your 70 psi reading is a non issue.
So, on to the next thing...,
Are you testing with the wire connected or disconnected at the AC compressor? I am not familiar with your test meter, nor do I know your skill level at using a meter for electrical testing. Many modern meters give a voltage readout, but when there is no electrical load imposed (something that an old fashioned test light did automatically), the test results can be misleading. For example: a damaged wire with only a single strand of wire operational could give the voltage reading one would expect to see with a modern meter, but an old-fashioned test light would light dimly, letting you know that there is a voltage supply problem.
It is for these reasons that I suggest using jumper wires (with a 20 amp fuse in series) to bypass the supply and ground circuits of the AC clutch. Doing so will give you conclusive results immediately.
Rig up your jumper switch by the passenger side fender well. Have AC gauges connected and operational. Start the engine - don't activate the AC. Go to the jumper switch location and activate the switch. If the compressor engages, you should see immediate action on your gauges. If it does not engage, then you have an idea where the problem is.
- John
Thank you for the clarification for the chart.
I just got back to the house after attempting to apply power to the coil and saw your message.
The Power Probe 3 (which is new to me, but is easily found and explained online and on Youtube) connects to the battery's + & - terminals and has a probe that tests for ground and for voltage.
It also has another ground at the probe so you can test components without them being on the vehicle.
By using the battery + & - it makes it a simple 1 hand project to test for ground and power and gives the voltage.
It also allows you to activate/apply power to, electric motors, solenoids, etc with the push of a switch just like the jumper you described.
I have been testing with the wires at the compressor disconnected, with the engine running and the ac button both off and on. Button off = no voltage at connector, button on = 14.7v at the connector and ground at other connector terminal.
There just isn't enough room for me to get 2 hands into the area and hold a grounded probe on 1 terminal and apply power to the other terminal'
I found a small alligator clip and I attached a wire that made it possible to connect the ground located at the Power probe.
This gave me the ability to finally and safely get into the tight area and apply power to the coil while only touching 1 terminal.
I didn't have the engine running, but 12.7v did not engage the clutch, it spun just as easily as it does w/o power.
I may be wrong, but it seems to me that if the electromagnet was working, it would still work without the engine running when it has a ground at 1 terminal and power at the other terminal, wouldn't it?
If you feel that the engine should be running when the coil is provided both power and ground remotely, I will test it again tomorrow.
Thank you for your help
Ken
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