gnarlycs

Okay, so I've spent the entire day with a buddy of mine and his step dad tinkering with my A/C system. At first we couldn't figure out why the compressor clutch wasn't engaging, turns out it was a bad ground for the pressure switch. We fixed that and the compressor clutch started working normally again. After a few hours (of on and off driving for like 20 minutes at a time a few times) of thinking we fixed everything I was letting it idle for a few minutes and then the A/C clutch started engaging and disengaging very rapidly making the car run really rough (making everything shake/vibrate). It ended up cycling like 15 times within the 5 seconds it took me to rush into my car to turn it off/take the key out. Now it does this same thing after a few minutes of idling every time. It's weird cause I've only noticed this happen while idling, works fine when I'm driving.

But I've been unplugging the wire harness that goes to the compressor clutch and condenser fan so the car is drivable.

One thing to keep in mind is that there is always nice cold air coming out of the vents whenever I have the car running and the wire harness is connected.

Another thing is that the A/C button inside the car isn't turning the A/C off (the compressor clutch is still engaging and disengaging like it would when the A/C is on). Even while I have the fan setting set to off (when it should be turning the whole system off, I can feel very cold air slowly coming out of the vents (fan is off). The odd thing is when I turn the button on and off, the condenser fan will turn on and off with it.

Lil Gnome

iTrader: (1)

Sounds like a faulty switch. Or a short to ground somewhere along the electrical path to compressor clutch.
-Check the wiring from compressor to switch
-Check all ground involved

gnarlycs

Well in order to fix the pressure switch we had to short the white wire to ground. Now that I think about it, we might have done that backwards and shorted it before the switch, not after. All I know is that the wire that is supposed to come out of the switch and be grounded to the frame isn't doing that. That was the original problem.

Former User

The problems are most likely related to your pressure switch "fix". Your "fix" was not a fix. You probably just grounded the pressure switch wire, which would bypass both the pressure switch and the A/C button and cause the compressor clutch to engage whenever the engine is running. If you don't soon undo your "fix", you will destroy the compressor.

In the unmodified A/C circuit, the pressure switch gets grounded via the A/C button.

gnarlycs

Well without my "fix" the compressor clutch never engages regardless of the A/C button.

Former User

Your "fix" will destroy the compressor if you leave it as is. That's not a fix. That's making a simple problem worse.

gnarlycs

It's still a somewhat fix because it's making the compressor clutch engage and cold air is coming out of the vents in the car. Which is why I also put quotations around the word itself because I realize that it isn't a good fix. It needs to be removed and I need to find out why the switch isn't working. However, that's what I spent all day yesterday trying to do. Thus why I came to Honda-Tech for help.

Former User

Obviously, a "fix" that will soon destroy your compressor is not a fix.

Step 1 - Disconnect the grounded wire.

Step 2 - The pressure switch for a 98 Civic has two wires: Blu/Red and Blu/Wht. Which one did you ground? How did you do it? Did you first unplug the pressure switch? Post a picture. This information is crucial because it will help pinpoint the real problem.

Step 3 - Borrow or buy a multimeter as you will need it for electrical tests.

gnarlycs

I spliced into the Blu/Wht wire and ran a short wire from it to the frame to ground it. The switch is still plugged in.

I already own an expensive multimeter and I used it a lot already.

Former User

This^ tells you the pressure switch is good.

What did you discover?

gnarlycs

When I ran a continuity test from Blu/Wht to frame there was no continuity. And with Blu/Red there was like 9 mega ohms of resistance. I tried to follow the Blu/Wht wire to see where it went to see if it had been cut because I assumed that was the wire that went to ground but I couldn't keep with it because it went into a bigger harness of wires.

Former User

Do this:

Remove glove box. Unplug the 3P connector for the A/C thermostat that plugs into the evaporator. Turn the key to ON(II). Measure voltage to body ground at the Blu/Wht wire terminal in the free 3P connector. Post the voltage.

gnarlycs

This is what you're talking about?



That Blu/Wht wire to body ground is reading 12 volts with the engine not running.

Former User

Good. Plug the 3P connector back into the thermostat.

Remove the center lower dashboard cover and unplug the 14P connector for the heater control panel. Turn key to ON(II). Now measure voltage at terminal 11 for the Blu/Red wire. What voltage do you read?

gnarlycs

10.9V

Former User

Turn key off. Use a piece of wire to ground terminal 11 to the metal frame under the dash. Turn key to ON(II) (engine off). Does the condenser fan run and does the compressor clutch engage?

gnarlycs

How am I supposed to tell if the clutch engages if the engine isn't running?

Also, am I plugging both of those connectors back in to test this?

PRcivicHB

He probably meant to turn the car on.

gnarlycs

Okay well I plugged that 3P connector back in and did the short to ground on the 14P connector like you said, I turned the car on and the condenser fan turned on (that usually always turned on before like normal with the A/C button). Then I turned the car on and watched the compressor clutch for a minute and it never engaged

Former User

The engine does not need to be running. Just turn the key to the ON(II) position. You will hear a click sound if the clutch engages.

For the test all connectors are plugged in, except the 14P connector.

gnarlycs

Okay well I didn't hear the click and all connectors were plugged in except the 14P connector.

Former User

Did you ever mention this before? If so, I missed it.

This^ and the information above it completely change the direction of the troubleshooting and tell you that the Blu/Wht wire is broken somewhere between the pressure switch and where it splices to the same colored wire coming from the fan relay.

gnarlycs

Yeah I'm pretty sure I mentioned it in the OP, if not I must have been confused when typing it because I was tired and I was telling people in person about that all day.

Also, yes that's what we figured yesterday, that the Blu/Wht wire was broken and that's why we spliced into it to connect it to ground.

BTW, should the pressure switch have 0.02 ohms of resistance within itself?

Former User

The fact that the condenser fan runs when the A/C button is pressed was never mentioned (i.e., without the pressure switch wire grounded).

The pressure switch is fine.

The Blu/Wht wire runs from the pressure switch to the hood fuse box (terminal 2 of C352). Measure continuity between those two points. If the wire is fine, then the hood fuse box is bad.



If the wire is bad, locate the break and fix it or run a new wire to the hood fuse box.

gnarlycs

How am I supposed to check continuity from the hood fuse box, stick a DMM probe in a pin slot where a relay goes? If so, which relay and which pin? I assume 87a or 30, which relay?