AC compressor not engaging...what are my options?

[bnelsonjax]

if the AC compressor doesnt engage when you turn it on, what all could it be?

what are my options for testing to determine if its a bad compressor?

[bnelsonjax]

anyone?

[Burnsey]

i'd post in Nissan Online Mechanic section too ... I think it might be more active than here and also that's kinda like a universal (ish) thing so there might be more ppl to try and help you... fyi.

[ricebike]

1st thing to check:

are you low on freon/ if the system detects no/low freon, the ecu will not let the compressor run 'cause you'll seize it up!

[bnelsonjax]

opps, forgot to mention that. I had the system checked and it was not low on freon.

[let5l1de]

check for power at connector on compressor when activated... its possible the you have power however the clutch is broken or malfunctioning. btw... i have a compressor if you need one.

[Burnsey]

post up car specs also (ie The car is an 89 240sx sohc, stock with 128,000 miles) ... cause it might be maintence related or something who knows ... anyways it always helps.

[Goldeneagle]

Check all of the A/C related fuses before you check the connectors for power.

[amolao]

Yes make sure that you are getting power to the compressor, Is it noisy?? squealing like a pig?? can you smell something burning??? then the clutch is gone....You will need a new one and possibly more AC parts if contamination got in the system...

[bnelsonjax]

Yes make sure that you are getting power to the compressor, Is it noisy?? squealing like a pig?? can you smell something burning??? then the clutch is gone....You will need a new one and possibly more AC parts if contamination got in the system...

im gonna check the power to it right now. it dont squeal nor smell....some days it works and some days it doesnt which makes me think its not a bad compressor.

[bnelsonjax]

ok there is no power getting to the compressor. I checked up to the AC relay and the AC relay is getting power. I checked continuity from the AC compressor wire that leads to the ac relay and its got continuity so im still trying to solve why the compressor wire is not getting voltage.

any other ideas?

[bnelsonjax]

according to the Troubleshooting manual my next step is to check the ECCS control module. but i dont see where its located. any clues?

[benemorius]

Well you've pretty well narrowed it down. If the relay has power but the compressor doesn't then it has to be either a bad relay or bad wiring between the relay and compressor. It will be harder to diagnose because it's intermittent. You can swap the relay with a different one or one from the junk yard for free or cheap, and you may want to run a separate wire from the relay to the compressor temporarily. When your problem goes away and doesn't return then you know you've bypassed the problem.

There is no reason to check any farther back than the relay if it's getting power. The ECCS is behind the passenger side kick panel, though.

[bnelsonjax]

forget my last post i had the wrong wire. im still working on the problem, getting closer to it
Modified by bnelsonjax at 6:40 PM 8/31/2006

[bnelsonjax]

ok after more testing the results say its my dual-pressure switch at the AC drier.

my question is anyone know where i can get a new one? or is it part of the drier and I just replace the drier?

thanks

[benemorius]

It can be removed and replaced. Unfortunately you will have to have the refrigerant removed in order to do so. I'd test to make sure that's the problem first. You can disconnect it and use a wire to short the two pins in the harness. If your a/c works, then that was the problem. You really shouldn't do any of this if you don't know what you're doing. The whole purpose of the dual-pressure switch is to keep the compressor from running when the pressure in the system isn't where it's supposed to be. When you're low on refrigerant, this is what keeps your compressor from killing itself. When your pressure rises dangerously high, this is what keeps you and anyone else in the vicinity alive.

[bnelsonjax]

we'll I decided to clean all the connectors and put the entire wiring back together. Oddly enough after doing so my AC is working again. LOL maybe some connection was loose and I fixed it by reconnecting it.

Thanks for your help.