Honda A/C Intermittent Problem

[quote=”Stokes” post=141556]I don’t have a manifold, but the high pressure side of my system reads about 180lb with the gauge attached to a recharge can.[/quote]
The high-side service port fitting shouldn’t fit a recharge can. It is a supposed to be physically larger than the low-side port to prevent recharge cans from being attached to the high side.

I’ve swapped around the A/C relay with another, just to see if there was something intermittent there, but it didn’t change anything.

That was a good idea, but I’m not surprised at the result. This sounds like a control issue. Either your pressure switch may be faulty, or the evap thermistor could be going bad, or there could be a bad fuse or wiring fault.

On a properly charged system, the low and high side pressures should be nearly equal when the system is off. This is called the static pressure, and should be somewhere around 100psi, depending on outside air temperature. When operating, the low-side should be between 35 and 40 psi, and the high-side between 200 and 250, again, depending on outside air temperature. Without a proper set of gauges you will not be able to read and compare the pressures. As Eric has said before, A/C work is very difficult, and dangerous, for the DIY. You may be better off going to a shop and paying for an A/C service. That costs about the same as good set of gauges anyway. At the very least, they can tell you what is wrong with the system if there is a bad part.

I am chasing the exact same problem on my 2008 Honda Civic- AC for the first several minutes then nothing.

In my case I have 13.8V going to the clutch while it’s failing so I will be checking that out when I have free time.

There is a three wire plug that leads to the compressor below. The middle wire is the power to the clutch. Measure that voltage relative to battery neg while AC on but failing. If you measure battery voltage the field coil is bad or the wiring to the coil is resistive or open.

You can also unplug it and measure resistance between center pin and battery negative and you should read 3-5 ohms.

The outer two wires of that same plug is the thermal switch that is read by the control unit. The switch should be closed.

Wiring diagrams will help. Also run the built-in HVAC diagnostic self-test. If the evap thermistor is bad it will show up there. In case you don’t have a wiring diagram, I’ll post one (2006-2008).

[quote=”Stokes” post=141606]I should mention that the reading off my can was actually 85lbs measured on the low pressure side after everything quits working. The numbers I gave before we’re from faulty memory.

I’ve only dug on my wiring with a logic probe and see that the middle wire to the clutch is hot, the two others seem to go to ground, so your info is helpful. I’ll try a DMM on it next. There are also three wires going to the pressure switch as well. Any ideas what I should be doing there?[/quote]

If the middle wire to the clutch is hot then your clutch coil or wiring is suspect. Next you should measure resistance from that middle wire (unplugged) to the battery neg post.

That pressure switch-middle wire should read between 0.696 and 1.944V. Here is a diagram for troubleshooting that switch-

I realize this is an old thread but no answer was ever established. I’ve worked on a number of this generation civic and they are know for the compressor clutch coil giving out. It will work intermittently but after a time will open up. Best test for this is to run it until it stops then check continuity across the clutch coil. Controlers can go bad as well, but typically on this model i have found it is the clutch coil.