# AC compressor- 3 wires, not 1



## papereater (Sep 16, 2016)

Sheesh, bought a new comp for my civic ex 2001, and it came with 3 wires on the connector instead of one, and the connector doest even match. So Im hoping I can cut off my old connector and crimp it on the new one but what do I do with the extra 2 wires? 

The 3 wires on the new one are 2 black and one red. The 2 black go to the copper "plug" heat sensor(I think thats what it is called). And the 3rd wire is red, going to the coil. 

Am I completely stuck, people?


----------



## papereater (Sep 16, 2016)

Can I simply wire the 2 black wires going to the heat protector right into with the red hot wire- have all 3 wires into one, since my original setup is that way?


----------



## huesmann (Aug 18, 2011)

So your old-n-busted compressor has a single wire, as does the harness for the car—no other wires connect to the compressor?

Does the old one have the heat sensor you mention (it's probably a temperature sensor—switches off the compressor if it gets too hot)?


----------



## raylo32 (Nov 25, 2006)

Which connector? Clutch or pressure switch(es)? If the clutch it should only need +12v wire (energized by the relay on call for A/C) and ground. Maybe it had the ground connected up to the mount on the block so doesn't need a wire for that? And maybe you can duplicate that with the new one somehow.


----------



## papereater (Sep 16, 2016)

huesmann said:


> So your old-n-busted compressor has a single wire, as does the harness for the car—no other wires connect to the compressor?
> 
> Does the old one have the heat sensor you mention (it's probably a temperature sensor—switches off the compressor if it gets too hot)?


yes, it does have a temp protector sensor, kinds looks like a copper plug. Only one wire to the car's ecu/connector.


----------



## papereater (Sep 16, 2016)

raylo32 said:


> Which connector? Clutch or pressure switch(es)? If the clutch it should only need +12v wire (energized by the relay on call for A/C) and ground. Maybe it had the ground connected up to the mount on the block so doesn't need a wire for that? And maybe you can duplicate that with the new one somehow.


The connector/clip that powers the whole comp. And what powers the clutch too, I think. I think I can copy the setup my old one had and bypass the new one's paralell wiring by going direct to the temp protector, then onto the clutch wire. As long as I copy it it should work. I will let you know...


----------



## papereater (Sep 16, 2016)

Rewired the comp, for the hot wire to go directly to the heat sensor, then to the coil. I added some gas, but got no response from the compressor. Not good. I stopped adding after a can. Now Im wondering if that main line/wire even has continuity. If not, i will have to cut it off the heat sensor and go direct to the coil. 

I know- not the best situation, but have little choice. Anyone know how bad is it to bypass the heat sensor , I mean, how often can a comp overheat enough to do damage? 

IF I do have continuity, of course, I wont chop off the sensor. Just thought- I should 1st check the fuse. Maybe it blew for some reason.


----------



## raylo32 (Nov 25, 2006)

If you don't have sufficient refrigerant in there to make the low pressure switch the compressor will not energize. You can work around this by jumping the relay to engage the compressor and once engaged you can finish charging up to the spec. Best way is to add the exact total weight called for on the label under the hood. If you jump the relay and the thing still doesn't engage you probably still have a wiring problem.



papereater said:


> Rewired the comp, for the hot wire to go directly to the heat sensor, then to the coil. I added some gas, but got no response from the compressor. Not good. I stopped adding after a can. Now Im wondering if that main line/wire even has continuity. If not, i will have to cut it off the heat sensor and go direct to the coil.
> 
> I know- not the best situation, but have little choice. Anyone know how bad is it to bypass the heat sensor , I mean, how often can a comp overheat enough to do damage?
> 
> IF I do have continuity, of course, I wont chop off the sensor. Just thought- I should 1st check the fuse. Maybe it blew for some reason.


----------



## papereater (Sep 16, 2016)

raylo32 said:


> If you don't have sufficient refrigerant in there to make the low pressure switch the compressor will not energize. You can work around this by jumping the relay to engage the compressor and once engaged you can finish charging up to the spec. Best way is to add the exact total weight called for on the label under the hood. If you jump the relay and the thing still doesn't engage you probably still have a wiring problem.


There is Hope, Ray! So,I put in just a can (12 oz) of gas and started the 2nd can but the system somehow wouldnt "take the gas" meaning the gas couild not be introduced anymore- psi was about 90 , and it stayed there. So how could one force more in? The system was running meaning engine on, ac on. 

Yes, I did check and system spec is for 19 oz, +/- 2 oz. 

Not sure where relay is on a civic. Tips appreciated!


----------



## raylo32 (Nov 25, 2006)

You can also test the LP switch to make sure it is working. This is the switch that cycles your compressor on and off in normal operation. With low or no refrigerant it will be open circuit across the terminals, when it is above the setpoint (mid 20s IIRC) it will be 0 ohms across. If it is open circuit with 90 psi the switch is bad. Switch is in you A/C line and looks like this:

https://shop.advanceautoparts.com/p...ry Air System Mounted Cycling Pressure Switch


----------



## raylo32 (Nov 25, 2006)

The compressor has to run to get more in... but at 90 psi, it should have been running. See my previous posts. Sorry, I don't know where the relay is, but you should be able to find it. Most cars have a relay box... or trace the wires back from the compressor clutch connector.



papereater said:


> There is Hope, Ray! So,I put in just a can (12 oz) of gas and started the 2nd can but the system somehow wouldnt "take the gas" meaning the gas couild not be introduced anymore- psi was about 90 , and it stayed there. So how could one force more in? The system was running meaning engine on, ac on.
> 
> Yes, I did check and system spec is for 19 oz, +/- 2 oz.
> 
> Not sure where relay is on a civic. Tips appreciated!


----------



## raylo32 (Nov 25, 2006)

I also have to ask... did you get a vacuum pump and pull a proper vacuum on the system before adding? Hope so.


----------



## papereater (Sep 16, 2016)

raylo32 said:


> I also have to ask... did you get a vacuum pump and pull a proper vacuum on the system before adding? Hope so.


Definitely! Did a vac. I will follow up with your tip on checking resistivity on the low presure switch (should be on the condenser??)and that main wire from the clip to the end where it meets the coil.


----------



## raylo32 (Nov 25, 2006)

You really should try to find the electrical schematic and look at everything in the circuit to energize the A/C clutch. It is generally something like: Dash switch>ECU>low pressure switch>high pressure switch>relay>compressor clutch. Maybe some other stuff depending on the vehicle. But you get the idea.

The first thing I would do is jump the relay and see if it clicks in. If it does, then look at the other things to see where the signal fails.



papereater said:


> Definitely! Did a vac. I will follow up with your tip on checking resistivity on the low presure switch (should be on the condenser??)and that main wire from the clip to the end where it meets the coil.


----------



## papereater (Sep 16, 2016)

raylo32 said:


> You really should try to find the electrical schematic and look at everything in the circuit to energize the A/C clutch. It is generally something like: Dash switch>ECU>low pressure switch>high pressure switch>relay>compressor clutch. Maybe some other stuff depending on the vehicle. But you get the idea.
> 
> The first thing I would do is jump the relay and see if it clicks in. If it does, then look at the other things to see where the signal fails.


Jumped the relay, no luck. Now Im gonna jump the pressure sensor (right on top of the drier, near condenser. )

This might be my last hope for success.


----------



## papereater (Sep 16, 2016)

raylo32 said:


> You can also test the LP switch to make sure it is working. This is the switch that cycles your compressor on and off in normal operation. With low or no refrigerant it will be open circuit across the terminals, when it is above the setpoint (mid 20s IIRC) it will be 0 ohms across. If it is open circuit with 90 psi the switch is bad. Switch is in you A/C line and looks like this:
> 
> https://shop.advanceautoparts.com/p...ry Air System Mounted Cycling Pressure Switch


Ray, I got the compressor started!! I jumped the pressure switch (high, or low, I dont know), and the comp kicked in!! I checked for ohms and got 0.03 ohms at the 2 terminals. What do you think?


----------



## huesmann (Aug 18, 2011)

So maybe you're just undercharged? What kind of pressures do you get when you jumper the pressure switch?


----------



## raylo32 (Nov 25, 2006)

On some cars you have to jump the relay to get the comp to run in order to get sufficient charge in there to close the LP switch. But he had said he had 90 psi, which, if so, should be plenty to run the compressor. It is hard to tell exactly what is going on here. Don't have the schematic or enough data from the OP. 



huesmann said:


> So maybe you're just undercharged? What kind of pressures do you get when you jumper the pressure switch?


----------



## huesmann (Aug 18, 2011)

Yeah, I understand that, just didn't recall that he said he'd got 90 psi (assume that's on the high side).


----------



## raylo32 (Nov 25, 2006)

I believe he said he had that 90psi static, before it was running, so high and low would be equal and depending on ambient, which, looking at the chart, sounds about right for summer conditions. But hard to know for sure. Of course 90psi would be way too low on the high side if the comp were running.



huesmann said:


> Yeah, I understand that, just didn't recall that he said he'd got 90 psi (assume that's on the high side).


----------



## papereater (Sep 16, 2016)

Thanks for the concern, people. Yes, I did have 90 psi with just a can and a part can. Nothing happened with the comp. So we figured there was plenty of pressure in the system. I read tha most systems will jump at 20 psi(?). Anyway, a new switch was only $10. Arriving tomorrow. Got little to lose. Also, not much other options at this point, right? 

Thanks, guys. Will advise soon......


----------



## papereater (Sep 16, 2016)

raylo32 said:


> On some cars you have to jump the relay to get the comp to run in order to get sufficient charge in there to close the LP switch. But he had said he had 90 psi, which, if so, should be plenty to run the compressor. It is hard to tell exactly what is going on here. Don't have the schematic or enough data from the OP.


Right- I did try the jump the relay trick, with no result. Also, tried to find a wiring diagram for my civic 2001 ex, no luck. Not sure if I would be able to even read it though. but when jumping the pressure switch- BAM!


----------



## raylo32 (Nov 25, 2006)

You may be on the right track but I don't believe you jumped the relay properly. Generally all those other things are in series to either allow or prevent the relay from closing, so by "jumping it" I mean you put 12v directly to the compressor. It has to start then... unless the clutch is busted or the wires to it are broken.

The pressure switches should be easy to test... LP is open circuit when pressure is too low... HP is open circuit when pressure is too high. Both should be short (0 ohms) when pressure conditions are met. But they are cheap.


----------



## papereater (Sep 16, 2016)

raylo32 said:


> You may be on the right track but I don't believe you jumped the relay properly. Generally all those other things are in series to either allow or prevent the relay from closing, so by "jumping it" I mean you put 12v directly to the compressor. It has to start then... unless the clutch is busted or the wires to it are broken.
> 
> The pressure switches should be easy to test... LP is open circuit when pressure is too low... HP is open circuit when pressure is too high. Both should be short (0 ohms) when pressure conditions are met. But they are cheap.


Hmmmm, OK, interesting. The way I jumped the relay was from a youtube- I dont remember, but you pull the relay out from the fuse box for the comp. Then I started the car, with ac on high, then insetred a big paper clip into the 2 slots that are paralell. Hard to explain, there are 2 slots to jump out of the 4. 2 pins are perpendicular to the other 2, if I remember. The comp did not turn on. 

Would you have done it differently? Did i do it right?


----------



## raylo32 (Nov 25, 2006)

I'd need to see the schematic and figure out what pins are what. A relay is nothing more than an electrically operated switch. So you put voltage to the control winding, the relay shuts the load side contacts completing the circuit and energizing the equipment. Simple as that.



papereater said:


> Hmmmm, OK, interesting. The way I jumped the relay was from a youtube- I dont remember, but you pull the relay out from the fuse box for the comp. Then I started the car, with ac on high, then insetred a big paper clip into the 2 slots that are paralell. Hard to explain, there are 2 slots to jump out of the 4. 2 pins are perpendicular to the other 2, if I remember. The comp did not turn on.
> 
> Would you have done it differently? Did i do it right?


----------



## papereater (Sep 16, 2016)

While you were writing your recent post i swapped relays- with the condenser fan- same relay- and same problem. So I doubt its a relay issue. I also should mention I put the wire back on the pressure switch. Then started car, and comp started, with cold ac, and ran well steadily for 2 minutes. Then it started poltergeisting again- violently on/off/on/off, engine shakinmg like mad.

I pulled the connector off again from the pressure switch, comp stops, then jump it with paper clip, and comp starts again, but making scary sounds, all the while with paper clip attached. I did not want to continue further so pulled the paper clip off. If pressure switch is isolated shouldnt comp run smoothly while it is jumped? 

I will try to find a wiring diagram meanwhile.........


----------



## papereater (Sep 16, 2016)

wiring diagram for civic 2003 (same as 2001 generation):

https://www.hondacivicforum.com/forum/mechanical-problems-technical-chat-8/2003-ex-c-problem-83996/

Look at post #3 for diagram. Hope this helps, and thanks!


----------



## raylo32 (Nov 25, 2006)

No, it doesn't have to run smoothly if you jump the relay. All that does is energize the clutch to allow the engine to spin the internal parts of the compressor. Could be anything...electrical issue, mechanical problem with the compressor, etc. Another maybe stupid question... did you add the correct amount and type of oil to the new compressor?



papereater said:


> While you were writing your recent post i swapped relays- with the condenser fan- same relay- and same problem. So I doubt its a relay issue. I also should mention I put the wire back on the pressure switch. Then started car, and comp started, with cold ac, and ran well steadily for 2 minutes. Then it started poltergeisting again- violently on/off/on/off, engine shakinmg like mad.
> 
> I pulled the connector off again from the pressure switch, comp stops, then jump it with paper clip, and comp starts again, but making scary sounds, all the while with paper clip attached. I did not want to continue further so pulled the paper clip off. If pressure switch is isolated shouldnt comp run smoothly while it is jumped?
> 
> I will try to find a wiring diagram meanwhile.........


----------



## papereater (Sep 16, 2016)

Well, regarding the oil- the new comp came already filled with oil- I understand it is supposed to be for an entire system, but really, I did not bother to bleed/drain/clear out all residue oil from the entire system. Also, lets remember- old comp behaved exactly the same way as my new (wasted $$) comp, so i doubt oil is a factor. Makes sense? 

meanwhile, i have a crazy insane comp. Getting the new pressure switch today, but not 100% sure i should replace it, but such a small gamble. I did everything else.

Oh- Ray, were you able to find that wiring diagram that I posted? Was it any good?


----------



## raylo32 (Nov 25, 2006)

Post a video of this behavior if you can. Where is that thermal protector? Internal to the compressor or inline somewhere? I am not familiar with that.... or else never had cause to look into one. But if everything else is good, then maybe that's the problem?

Yes, I saw the diagram and it looks good. To jump the relay you'd need to connect pins 1 and 2 to send 12V to the clutch. Not sure how you could test that "multiplex unit".


----------



## papereater (Sep 16, 2016)

Will do that, Ray. Need a buddy to video it for me. Will call him. Thanks. 

Image of pressure switch location- on top of the drier. Not the same civic year, but same location. see post #2:

https://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/c-pressure-switch-question-2636017/


----------



## raylo32 (Nov 25, 2006)

For a video all you need is your phone and a free youtube account. Interesting that the pressure switch is combined. On the vehicles I have worked on there were separate LP and HP switches. I haven't had to work on my 2009 Tacoma or 2016 Vette A/C yet. Probably just jinxed myself!



papereater said:


> Will do that, Ray. Need a buddy to video it for me. Will call him. Thanks.
> 
> Image of pressure switch location- on top of the drier. Not the same civic year, but same location. see post #2:
> 
> https://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/c-pressure-switch-question-2636017/


----------



## raylo32 (Nov 25, 2006)

Just speculating... but being that the pressure switch is combined HP and LP it could be the problem. That is more complex than having separate switches and it could be messed up and jumping around between off LP, HP and/or "on" states. Maybe.


----------



## papereater (Sep 16, 2016)

raylo32 said:


> Just speculating... but being that the pressure switch is combined HP and LP it could be the problem. That is more complex than having separate switches and it could be messed up and jumping around between off LP, HP and/or "on" states. Maybe.


Thanks for the continued "good to know" feedback. Yes, I imagine those are more complicated and more prone to malfunction. Thats good for me! Easy to pop a new one in and cross my fingers!

Youtube account- my buddy.


----------



## raylo32 (Nov 25, 2006)

Another thought... This pressure sensor may not work like the ones I have seen before that simply have on and off states. It may instead provide a continuous but variable signal to the ECU that depends on the pressure it senses. Then the ECU decides along with the other conditions (switch position, etc.) whether to engage the relay and hence the compressor.

If you haven't already you should be on a Honda forum where it is likely you'll find others who have had a similar problem. There are some decent mechs here but when we don't have specific experience with your particular manufacturer or vehicle we have to make assumptions and semi-educated guesses.


----------



## papereater (Sep 16, 2016)

Heres the video:






This time, figures- engine was not shaking violently. I noticed the pressures were a bit high, right? Also, comp is cycling too frequently, and air in cabin doesnt have a chance to get cold. Thoughts appreciated.


----------



## raylo32 (Nov 25, 2006)

Whoa... Pressures are VERY high. I believe it is cycling off on high pressure. Maybe way overcharged. Or some sort of blockage.


----------



## huesmann (Aug 18, 2011)

That's like double the pressure you should be seeing!


----------



## raylo32 (Nov 25, 2006)

Yup... and the only thing keeping it from going even higher is the high pressure switch shutting off the compressor!



huesmann said:


> That's like double the pressure you should be seeing!


----------



## papereater (Sep 16, 2016)

Yikes, people!! Wow, glad I did the video! Thanks for the quick feedback! You guys are great, who needs the civic forums! I myself was shocked at the readings when I saw it. But I wanted to leave it for your to comment. 

Guess i will release some gas, or have a shop suck it out, then weigh in the right amount. 

Only thing- why the heck didnt the comp start when I added the 1st can bringing it to 90 lbs???? (scratching scalp, left elbow on desk....)


----------



## papereater (Sep 16, 2016)

Oh- may not matter now but static (engine off) psi was 125 at 90 deg F.


----------



## raylo32 (Nov 25, 2006)

Static pressure is really pretty useless other than a basic check. As long as there is some liquid you have a saturated system and the pressure will be the same whether under charged, properly charged or over charged. 125 is high but after running the system to make that video your engine compartment is considerably warmer than the ambient 90 degrees.



papereater said:


> Oh- may not matter now but static (engine off) psi was 125 at 90 deg F.


----------



## papereater (Sep 16, 2016)

All working well now, people, I cant believe this whole mess. Didnt have to put in a new presssure sensor. I think the idea of a video helped. 

Thanks for all the help. (who knows how long it will behave, this comp).


----------



## huesmann (Aug 18, 2011)

So what did you do?


----------



## raylo32 (Nov 25, 2006)

I can surmise what he did. ;-) But I don't know what the original problem really was.



huesmann said:


> So what did you do?


----------



## papereater (Sep 16, 2016)

LOL!! People, all I did was have a local shop suck out a tad of gas, and put guages on the ports again, and observe psi's, and the comp behaved nicely. Like yous said, way too much gas in system based on my video. I also had the guy offer an opinion hands on, after this whole fiasco. I am suspicious this system will act up again. 

I dont trust it. Stuff happens.


----------



## raylo32 (Nov 25, 2006)

Glad you got it working. But just FYI, it isn't really "gas". The system is 2 phase, liquid and gas, and cools inside and rejects heat outside by changing those phases. There is always liquid in there even when it is shut off.... unless you have a catastrophic leak and have lost 99%.



papereater said:


> LOL!! People, all I did was have a local shop suck out a tad of gas, and put guages on the ports again, and observe psi's, and the comp behaved nicely. Like yous said, way too much gas in system based on my video. I also had the guy offer an opinion hands on, after this whole fiasco. I am suspicious this system will act up again.
> 
> I dont trust it. Stuff happens.


----------

