First, a little background. The car is a '99 Honda Civic EX, automatic. A couple of months ago, the crankshaft pulley failed, and I did not have time to replace it then, so the car has sat for a couple of months. Occasionally I have started it to make sure it keeps running, usually requiring me to charge up the battery. I tore it apart a couple of weeks ago, to diagnose and ensure that the crankshaft pulley/harmonic balancer was the only problem, it was. I decided to fix it last night, everything was already pulled apart, put the new crankshaft pulley on, torqued it to spec, reinstalled all the belts, cranked it up, everything running like it should, power steering, alternator, and a/c restored. So I thought. I decided to call it quits, as it was already 1AM. This morning, A/C was blowing a little hot, so I assumed it needed to be recharged. I usually have to recharge the a/c every summer. As I started digging in, I realized that the clutch wasn't kicking in, so I popped the gauge on the low side, and pressure was really high. So I relieved some pressure, and still no clutch engaging.

I haven't tried much, since I really don't have knowledge of the A/C system, it's components, or where they are located. I have tried switching the fan relay and the clutch relay, fan still operates as it should, so I know it's not the relay. The clutch will turn, so I also know the clutch is not seized. The A/C did work up until the point that the crankshaft pulley failed. The car was only driven a little bit, and I turned off the A/C system while it was being driven to keep from damaging components. The car idles up when the A/C button in the car is pressed, and the fan comes on, so I'm assuming it's also not the switch in the dash. I tried jumping the two pins in the relay, but that did not engage the clutch. I used a test light, and two of the pins lit up for ground, and two lit up for power. I'm not exactly sure which two I'm supposed to try to jump, but I tried different combinations, and none of them worked. I saw a diagram on how to pull DTC codes, but not sure this applies to my car, because I couldn't get it to work, no matter how many different variations I tried. I'm scratching my head, because I'm getting ready to sell this car, and I really need to get this fixed, although I'm also on a tight budget, and can't really afford to spend $300 on a new compressor, or $100 on the clutch. If anyone can please help, I would greatly appreciate it!

Edit: The relay that I tested was in the fuse box under the hood. I have checked all the fuses, and they are all okay.
Joshua

 

Update. I went out this evening to do a little troubleshooting from some suggestions from other threads. I did all of these tests with ignition on (position II), and A/C button on dash pressed/lit up (except where noted).

1. I checked the fuses again underneath the hood and in the cab. Fuses again under the hood are good, as well as the relays. Fuses underneath the dash are good. Took a test light to fuse 17 as suggested in another forum/thread, when fuse is pulled, a/c blower etc do not function, when replaced, blower turns back on. Heater works.

2. Unplugged the pressure switch, one with the blue/white and blue/red wires. Blue/red voltage is weaker than blue/white voltage, according to brightness of my test light (do not have a volt meter yet to test). When I ground out the blue/red wire, nothing happens. When I ground out the blue/white wire, the condenser fan turns on.
Unable to check continuity of blue/red wire at this time, will update when I can do that. Not sure if I had A/C button on when I did this test, will retest again tomorrow and ensure that A/C button is on, on dash.

3. Got in the floorboard on the passenger side to check ECU as per suggestions to other people in other forums/threads. Found what I believe is Connector A, pin A15. No voltage showing on test light, with a/c on and fan on. Grounded the pin out, nothing doing, no clicking, no activity from clutch. Looked at the other connectors and could not confirm which one was connector B, pin B5 in order to ground that one out or test with test light. If someone could help me figure out which one this is, I would really appreciate it.

Other things that I'm going to try.
test pressure in both high and low pressure lines (do not have manifold gauge yet)
test voltage at ecu for pin a15 and b5 (do not have volt meter yet, and not sure exactly which pins these are).
try jumping compressor off of positive battery post.
try jumping power from interior fan switch to compressor
check continuity between pin B5 of ECU connector B and blue/red wire on pressure switch
pull connector on AC compressor, turn AC "ON" and check for voltage.
Ground pin B5 directly to try to kick on compressor.

Any thoughts or suggestions?

 

The FAQs sticky is your friend. Become familiar with it to save yourself from headaches. For example, you'll find the 99-00 Civic A/C circuit diagram there.

You currently know very little about the A/C circuit in your car so stop randomly grounding wires. This is a great way to break things that are not broken. Also buy or borrow a digital multimeter as a test light has limited usefulness and also should not be used on delicate electrical components.

The Blk/Red wire from the compressor clutch relay runs to ECU connector pin A17. Unplug ECU connector A and test for voltage at that pin with the key in ON(II).

http://www.phearable.net/tech/wiring...schematics.gif

If voltage reaches the A17 pin in the connector, then test whether grounding it causes the clutch to engage.

 

if the low pressure side is reading high, you may have an issue with the receiver dryer, since you posted that you tried to relieve pressure by venting pressure on the low side, you have no knowledge of how AC works, stop messing with the wiring and have someone look at it who knows what they are doing before you destroy your system, you get an abnormal gauge readings then start looking for electrical issues?

 

I guess, at this point, it remains unclear whether the pressure reading was actually abnormal because the pressure reading or conditions of the test were not posted.

 

Haha, I can imagine what it sounds like after rereading my post. I didn't ground the pin in the B connector, because that's what I was trying to avoid, randomly grounding wires, which I'm sure would cause some issues and further breakage. I'll go check out the 99-00 Civic AC diagram. Like I said before, I'm going to borrow a volt meter/multimeter, but I haven't got it from him yet. Hoping to get it today. I will follow your instructions as soon as I can, may be after lunch before I'm able.

 

Thanks for your reply. The pressure seemed abnormal when I first started, but considering that the clutch was not engaging, the pressure reading was probably fine. Now that I've vented pressure, after I get the clutch to engage, I'm sure I'll have to add freon back in. Unfortunately, I don't have the option of having a professional look at it, and I haven't done anything so far that would destroy my system. I'm trying to rule out as much as I can, so that I can narrow down the problem, because I can't afford to just go buy replacement parts, especially the compressor, clutch or ECU, if that's not the problem. By checking out the electrical components, I can ensure that there's nothing electrical causing the problem. Do you have any suggestions for what I can check to help me?

 

I based my assumption of the pressure being high, based on the gauge that I use to add more refrigerant to the low pressure line. When I first popped it on, without a can attached, with the in ON(II), and the A/C engaged, the pressure was really high, and the needle went all the way around and back to the stop. The temperature was about 90, with a heat index around 98. While doing this, I realized the clutch was not engaging. I reasoned that the pressure being too high would cause the clutch to not engage, so I released pressure until it was in a normal range, clutch still did not engage. At this point, I realized there was something else wrong with the system, because it should have engaged at some point.

 

When the compressor clutch is not engaged, you are measuring the static pressure in the system. Static pressure is basically meaningless unless you get a very low reading, which means the system is empty. As you have released a lot of refrigerant to lower the static pressure, your system is now basically empty. This was an expensive mistake as you now must evacuate the system and recharge it with the proper weight of R134a. You now may as well repair the leak you know to exist. This is done by adding some R134a containing a leak detecting dye. Where dye appears is where the leak is.

 

I figured as much, which is what I realized after finding out the clutch wasn't engaging. Which is all dependent on whether or not I can actually get the compressor clutch to engage, if it won't engage, then it's not going to matter how much r134a is in the system! I'll get a set of manifold gauges in order to check the pressures, evac, and recharge, once I can get the clutch engaged.

 

have you tried to jumper the clutch relay directly to 12 volts to see if it even clicks? if there is a low pressure or high pressure situation in the system the clutch will be cut out to avoid damage. When you open the system you should replace the receiver dryer anyway, but it's possible a little bit of desiccant got in the orifice tube and partly blocked it causing a high pressure condition and causing the high pressure cutout switch to open

 

I'm assuming you mean the relay in the fusebox under the hood? If so, I switched the relays to ensure they were working properly. I also jumped pin 1 to pin 2 with the car ON(II), and the A/C engaged, with no result. Going to try this again in about an hour just to make sure I'm not missing anything.

 

We're engaged in a circular argument. Under normal conditions, the clutch won't engage if the system is empty of refrigerant because the A/C pressure switch will open the circuit.

 

no i mean unplug the connecter at the AC compressor and hook 12 volts to it and see if the clutch clicks, if it doesn't you've saved yourself a lot of troubleshooting time, this bypasses all the controls etc, to clarify I mean with the engine off

 

I understand. I haven't emptied the system completely of refrigerant. after I relieved pressure down to what would have been normal had the clutch been engaged, and I realized what was going on, I emptied a small can of refrigerant back into the system. Perhaps I can jump the compressor off like the other poster said just to see if I can get it engaged?

 

Okay, just to make sure I understand, I should unplug the connector wired to the red wire coming off of the compressor, and take another wire, connect it to the positive battery post, and jump that to the connector with the engine/key off to see if I can hear the clutch clicking?

 

right, if it doesn't work then, it's the clutch, if it does work, you've eliminated one possibility

 

It may be easier simply to use a multimeter to determine whether voltage reaches and gets past the compressor thermal protector.

 

It's very easy to test whether the pressure switch has continuity. You want to know this anyway. The more willing you are to do tests and post the results, the faster the problem will be pinpointed.

 

this is the simplest test in the world, 12 volts from the battery to the clutch wire will tell you immediately if the clutch is bad, if it doesn't click with direct battery power at the clutch wire, you are looking at another clutch or usually a rebuilt or new compressor, you could do all the other tests and pull your hair out trying to figure out why it won't work, when the clutch has gone bad, test this first and work backwards, itt could be anything from a loose wire to low pressure or high pressure, a bad pressure switch, bad clutch, bad relay etc, start at the clutch and work systematically backwards. OP have you verified the clutch relay is clicking?

 

I guess we'll agree to disagree. For me, what's easier than testing for voltage at the compressor? Either way, though, the question would be answered. The topic is moot for the time being, however, given that the pressure switch is open. And the other tests you mention are so easy.

 

well you can have a burned contact in the clutch relay and still read voltage, the best test there would be doing a voltage drop test at the wire feeding power to the relay, if there is a large voltage drop, there's a chance it's the relay, normally the relays on these are ground triggered, if the ground is jumped to the clutch relay the clutch should click, does someone have a wiring diagram for this setup? a lot of these also have a clutch delay/safety module

 

Okay, so the next thing I will try first will be to try to jump the clutch directly from the battery to see if I have any response. No response, I can safely assume that either the clutch or the compressor is bad, correct? For some reason, my gut is telling me that it is probably that the clutch has gone out and needs to be replaced.

 

No. The thermal protector could also be bad. A bad compressor is much more remote a possibility than a bad compressor coil or thermal protector. But all of these ideas are moot if no voltage gets to the compressor. Do you have a multimeter? If so, do the simple tests. It's pointless to make additional posts until you have test information to share.

Don't guess. Do the tests.

 

I'm not saying the compressor is bad, but if the clutch isn't working it's often cheaper to just buy a reman unit with clutch, if the clutch doesn't come on with direct battery power, then you have narrowed the issue down a long way, and you know the issue isn't something before the clutch