I have an AC problem I've been chasing in this car for a couple of years, it's a secondary car that I don't drive a lot, but I'm having issues figuring out what the problem is with the air conditioner.

The compressor has been replaced recently, twice in fact since I've owned the car, and the condenser was once recently replaced. My issue is that I am getting high pressure on the low side of the AC at times, especially when it's very hot out and it will only blow hot air, the system sometimes works when it's not as hot and will cool temporarily but will eventually start to blow hot air as the car warms up.

Also, if anyone knows, what are the high side and low side pressure supposed to be during regular operation?

 

Hey have you tried the a/c pressure sensor switch? That was a simple fix for me its worth a try.

 

I haven't had gauges on my car but typically high side will be like 200-250 and low side will be 40-70 depending on ambient temp.

Does the compressor cycle on at all? High side pressure doesn't mean much unless you can watch low side as well. If your low side immediately drops when the compressor kicks on, then the compressor shuts off, and cycles like that then you're probably just low on refrigerant.

Why on earth does it have two new compressors in that short of a timespan? Even in the worst conditions with a kaboomed compressor that **** up the lines and it wasn't cleaned and the new compressor ate all those shavings it's still going to run for a few years before the new one Kabooms as well.

 

I'm getting high pressure on the low side.

I think the 1st time the compressor was actually bad. The 2nd time the compressor was replaced because I was really close to the end of the warranty on the 1st one and wanted to replace it in case it was the problem, but it wasn't, it appeared worked temporarily because that repair occurred when it wasn't really hot outside....but anytime it's really hot outside the system really hasn't worked at all.


Do you know what the total capacity of the system is?

The both the compressor and condenser have been recently replaced common the condenser mostly because of the radiator, I went to Firestone today and for their $10 check they told me that the compressor and condenser were bad at long with leaking service port valves. And that I was down 16 oz of free I'd, and I pretty much know that all 3 of those statements were bullshit....

I'm just having trouble finding what the problem is. The only thing that hasn't been changed is the expansion valve and comments that I received from here and the guy that did the compressor work are that there's possibly a blockage in between the compressor and the expansion valve

 

I think I have changed it before, but I could try it again As it had been working properly since I've done that. Though it is not working properly now. Do you know a way to check the switch?

 

It's probably just the expansion valve if you're reading high on the low side, it's just a super fine mesh screen and if you kaboom a compressor it ***** ALL the guts as a fine metal paste right into the expansion valve.

Since you're already low just evacuate the system and pull/replace the expansion valve, usually it's in the stem of the condenser right at a fitting but do a little google search before pulling anything apart. If it's all plugged full of crap you probably found the issue but you can still blow out the line by hooking an air compressor to the suction line on a manifold set and blowing out the line set.

I've never been too concerned about using an air compressor for this, yes you SHOULD use nitrogen bit were talking about a 15 year old system that's already had multiple failures, a little compressor oil isn't the end of the world and you're going to vacuum it all down before refilling anyways (hopefully...) so it's not a huge deal.

If you blow out a bunch more chunks you should just replace everything or at least wash it all out as thoroughly as possible (and replace the dryer). Compressors don't like to eat metal shavings.

Factory specs are in the FSM section ATC I think, check section FWD - Forward to verify.

https://www.nicoclub.com/infiniti-service-manuals

 

This is pretty much what the guy that changed my compressor and condenser was saying, I've already purchased the expansion valve but we were looking for reliable 2nd opinion so thanks for that, I may go in after the expansion valve tomorrow as I've seen a YouTube video that only requires taking out the glove Box and not the whole dash.


By the way, it's not actually low, Firestone is just full of ****. I went back to my friend right after....The condenser was not leaking as they claimed, When I ask them for details on where the condenser was leaking and why the compressor was bad, they catfished and went to the back, had a discussion and came back correcting themselves and asking me if I just wanted to take the car and go.... the service ports were NOT leaking, and the freon was pretty much full.

Thanks for your input

 

Before tearing the system apart, does the compressor cycle on AT ALL. You would hear a distinct CLICK sound come from the engine bay with the hood open if it is trying to cycle on. Then another CLICK as it cycles off for whatever reason.

If it doesn't cycle at all it could be something else with the electrical circuit, you can test for voltage at the compressor, power engages an electromagnet that pulls a clutch disc onto the compressor. Typical causes are either a blown fuse/relay or the low pressure switch failing in the open position. You can test the low pressure switch by unplugging it and using a paperclip to jumper across the two pins in the harness. It closes a ground, not power, you won't get shocked or ruin anything if you screw up (can't really screw up...).

 

The compressor does click. Can even notice a small RPM blip when it comes on at idle.

I haven't tested the switch yet, but I changed the expansion valve and it did not solve the problem really.

The A/C was not working. Compressor was coming on, but according to the gauges, the refrigerant was not circulating. and then I parked the car halfway into the garage, so the hood was out of direct sunlight and after about 10 minutes when it cooled down, the car began to cool. And it continued to run as I let it sit there. This is the same thing that it was doing before. It works when there's not a large heat load on the engine bay, like when it is in the shade, or it's night time.

I had noticed this before and someone here on the forum suggested that this was a symptom of having too much refrigerant in the system. In the past, I would vent a little, and the system would start working again. That is really not working now either, but cooling the engine bay seems to work for a while, until I drive in the daytime and it gets hot again.

 

I think you actually have an electrical problem. The car uses the ambient air temp sensor located on the right/passenger side of the grill. The cabin ambient air temp sensor which is above the gas pedal on the dash near your knee, looks like a little quarter sized set of "slots" in the plastic where it sucks air to the sensor. Also uses a SUNLOAD SENSOR on the dash.

I think your SUNLOAD sensor is screwing up causing the problem.

You can put the controller into a self diagnostic mode to check all the individual components for function. Do this both when the AC is working and when the AC is not working. I'm betting the sunload sensor is either shorting or opening it's circuit causing the whole system to fail.

You can also test that the sunload sensor is the problem by using black electrical tape and taping over the thing, it's a round flat circle on the dash up near the window sort of by the VIN number. It's an absolute pain in the *** to remove that thing if it is the problem. Don't follow the instructions in the FSM just remove the instrument cluster and use a long pair of needle nose pliers to disconnect the harness through that hole. Otherwise it's almost literally taking the ENTIRE dash apart.

If black electrical tape over the sensor "fixes" the issue I would just leave the tape on permanently until you have some other reason to go tearing the dash apart.

 

Thanks...I will try this first.
There are 2 of these, right? One on the driver's side and one on the passenger side?

 

I'm not sure about the V36 platform but the V35 only has one for the AC controller. The other one might be for your automatic headlights but I'm sure you'll figure it out quickly if that's the case.

I would tape them both off to start with though.

 

As it was this morning, when I went out to lunch and taped the sensor off, everything was working. But I'm in the car now headed home and it's about 10ﾟ warmer, and the Sun is out, and it's not working.. There was some overcast earlier that is now gone.

It is about 85ﾟ now as opposed to 75ﾟ around noon

 

Time to throw some gauges on the system and see where your pressures are at when it finally shuts down. See if you can take a video of the gauges, post it to youtube then put the link here in the message body and it will automatically embed the video.

If not then just take a few photos of the gauges before and after the compressor stops running. Ideally you would be standing right at the gauges when the compressor clicks off so if that requires driving the car out into the sunlight see if you can have someone else do it so you can record/photo while it's happening.

 

Also run the AC amp through all the self-diagnostic functions. FSM section ATC - Automatic Air Conditioner under "self diagnosis" to see if it's finding any errors.