# 07 versa power not getting to AC compressor



## nukes1810 (Jun 26, 2021)

Bought a 07 versa for a relative, budget was a bit tight so had to get one with high miles 160k but engine and trans in great condition. How ever when we bought It the ac compressor was bypassed from the alternator to the single compressor not sure if this caused any further damage but the ac did work and we decided to get rid of that contraption and see what's wrong. The 10a fuse is good on the ipm did the relays can be replaced but aren't labeled so not sure which relay on It is the ac compressors, any help is greatly appreciated


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## VStar650CL (Nov 12, 2020)

The compressor relay isn't one of the replaceable ones on the outside, it's internal. Compressor power should be coming out on a white wire, pin 11. If that terminal is hot, then the wire to the compressor is broken somewhere (there are no intervening connectors). You can test the compressor relay by doing an IPDM self-test, push the driver's door switch 10 times quickly with the key-on-engine-off. The IPDM will go into a test mode. Somewhere in the middle of the tests it should cycle the compressor clutch on and off 5 times, just listen for the clicks.

The way the AC works on Nissans is a multi-step process. For your Versa, it starts with the AC switch signal to the BCM. The BCM also monitors the Thermo Control Amplifier on the evap, and if it already shows "cold" then the BCM signals the IPDM via CAN to kill the compressor. As a result, if the thermo is blown, the compressor will never switch on. To check it, jump the black and gray wires at the thermo together and see if the compressor switches on, if so it's a bad thermo. This is a common failure item.

If the thermo checks okay, the BCM then sends a CAN request to the ECM, which monitors the AC pressure sensor. If the pressure is low or high then the ECM vetoes the request and kills the compressor. The sensor is located on the receiver/drier and the gray wire is signal, it should read about 1V static and 1.2~1.5V with the compressor on. They usually fail flatline (0V) when they fail. This is also a common failure. Hope this helps you out.


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## nukes1810 (Jun 26, 2021)

VStar650CL said:


> View attachment 7487
> 
> 
> The compressor relay isn't one of the replaceable ones on the outside, it's internal. Compressor power should be coming out on a white wire, pin 11. If that terminal is hot, then the wire to the compressor is broken somewhere (there are no intervening connectors). You can test the compressor relay by doing an IPDM self-test, push the driver's door switch 10 times quickly with the key-on-engine-off. The IPDM will go into a test mode. Somewhere in the middle of the tests it should cycle the compressor clutch on and off 5 times, just listen for the clicks.
> ...


What do you mean if the terminal is hot as is physically hot? I did a continuity test with the meter from wire 11 to the wire on the compressor and there is no contuniation, also where do i fND the thermo control amp


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## VStar650CL (Nov 12, 2020)

nukes1810 said:


> What do you mean if the terminal is hot as is physically hot? I did a continuity test with the meter from wire 11 to the wire on the compressor and there is no contuniation, also where do i fND the thermo control amp


No, hot as in "having voltage". If the compressor wire is open then that may well be your culprit. Try jumping it out with an external jumper wire to find out. Vis the thermo, I should note that if your car has a CVT transmission then there isn't one, in '07 only the M/T and conventional A/T cars had one. If your car does have it, the connector will be under the dash on the righthand side of the HVAC Unit, with a wire that runs directly inside the HVAC. You probably need to remove the glove box to get at it. The sensor itself is clipped to the evap and the only way to change it is to remove the HVAC. Big job if that turns out to be the issue.


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## nukes1810 (Jun 26, 2021)

VStar650CL said:


> No, hot as in "having voltage". If the compressor wire is open then that may well be your culprit. Try jumping it out with an external jumper wire to find out. Vis the thermo, I should note that if your car has a CVT transmission then there isn't one, in '07 only the M/T and conventional A/T cars had one. If your car does have it, the connector will be under the dash on the righthand side of the HVAC Unit, with a wire that runs directly inside the HVAC. You probably need to remove the glove box to get at it. The sensor itself is clipped to the evap and the only way to change it is to remove the HVAC. Big job if that turns out to be the issue.


The co.pressor was jumped via the alternator, and the ac did work. And I tried doing a continuity test from wire 11 at the ipdm and the wire at the compressor no connection there not sure if that wires goes through any other components but the harness is in great condition so hard to believe there is a break, I also checked for volTage at the compressor connector and there was none just a few mili volts


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## VStar650CL (Nov 12, 2020)

No, there are no intervening connectors. It's a single wire from the IPDM to the compressor. One possibility is a bad pin-fit at the connector on the compressor side. We often see that with aftermarket compressors, the connectors aren't quite right and the pins don't make good contact with the car harness. Back-probe the connector while it's mated and see if there's a big voltage drop from one side to the other, if so then that's your issue. The male connector pins can usually be twisted slightly to make contact if that's it, but make sure not to bend the pins, just twist them about 10~15 degrees. If they bend then they may not find the holes when you try to plug back in, and forcing them will flatten the bent pin and make an even bigger problem. I usually use a hemostat instead of a needle nose, it's easier to control the amount of twist without accidentally applying too much force.


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## nukes1810 (Jun 26, 2021)

I'll give that a shot the compressor seems to be the original one. Also when the ac is on there should be 12v on that wire? Because I don't get any voltage on it


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## VStar650CL (Nov 12, 2020)

Yes, you should see 12V at pin 11 and at the compressor when the AC is turned on. If there's voltage at 11 but not the compressor, then the wire is open. If there's no power at 11, then the problem is one of the other things I mentioned. Like I said, the easiest way to confirm if the IPDM is working is to put it into self-test mode. If you hook a test light between pin 11 and ground, you should see it blink on and off several times when the IPDM exercises the compressor relay. If so, and if you hear the clutch click along with it, then the drive circuit isn't the problem and something else is causing the BCM or ECM to veto operation.


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## nukes1810 (Jun 26, 2021)

Thanks for all the help so I confirmed it is getting power least to the connector, I checked the pressure on low side while the ac if off and ot was around 110psi but cannot confirm what it is when the system is running because the compressor haven't kicked in without bypassing it. I purged till about 30 and didn't kick on either, when I purged it was just air bo oil or uv color. What could it be now


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## VStar650CL (Nov 12, 2020)

You're most welcome. If it has power to the connector and works when you jump it, then the only thing left is that power (and/or ground if it's a 2-wire type) isn't making it _through_ the connector. Check voltage drop across it, you probably have bad pins.


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## nukes1810 (Jun 26, 2021)

Ot is a single pin connector I'll get some ramps tomorrow.and check the pin


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## nukes1810 (Jun 26, 2021)

So figuredouthe problem it won't get powe under load, when it is not connected to the clutch it gets 14v no problem but when it is there is no power, could it be the ipdm


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## VStar650CL (Nov 12, 2020)

Yep, that sounds like high resistance in the relay contacts. If it was low resistance in the clutch it would be blowing fuses. Nothing for that but a new IPDM.


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## nukes1810 (Jun 26, 2021)

I swrapped the ipdm stI'll the same guess ots a bigger issue than imagined will ot be OK to bypass ot with a relay


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## VStar650CL (Nov 12, 2020)

If the terminal at the IPDM is going hot but it won't drive the compressor, I suppose you could use it as a signal to drive a relay. You really don't want the compressor on without the ECM knowing about it, that can cause a whole host of backdoor problems.


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## nukes1810 (Jun 26, 2021)

So I noticed the wire 11 is not directly connected to the compressor i checked continuity on it from 11 to the compressor harness and nothing, but when the ac switch is on it gets 14v where is that wore going to and where is the wire for the compressor coming from, the could it be something wrong with the climate controls the ac switch has to be pressed harder to turn on or off so could it be the switch


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## VStar650CL (Nov 12, 2020)

That wire on 11 should be going straight to the compressor with no intervening connections or splices. The easiest way to see if the open wire is the problem is to jump a test wire from 11 to the compressor connector. If the compressor turns on and off the way it should when jumped, then the wire or the harness-side connector is causing the issue.


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