Troubleshooting AC System - Blows Hot Air - Still Full of Freon

[M35Soup]

Good Evening,

My AC, which is full of Freon, is blowing hot air. The compressor/clutch won't engage either. The switches on the dash work, as when you push the AC button, the engine idles higher, but still no clutch engage.

So I'm trying to come up with a checklist to troubleshoot and here's what I have so far:

1. Jump the AC pressure sensors - I have no idea where these are located so a link or diagram would be great if anyone has it. I want to try and engage the clutch to see if it blows cold.
2. ??? - no idea

Any help or suggestions would be appreciated.

[Ilya]

For the diagram, I'd check the FSM (see link in my signature in the HowTo) and see if that can't point you in the right direction.

[M35Soup]

For the diagram, I'd check the FSM (see link in my signature in the HowTo) and see if that can't point you in the right direction.

Thanks for the links! Great info.

So I found the pressure sensor, and it's attached to a long skinny tank. Is there a way that I can jump the sensor to try and engage the clutch? I want to make sure I do this correctly. The manual doesn't go into detail on this troubleshooting.

[M35Soup]

Just a quick update, I was searching and found this info on doing a self test, where the magnetic clutch should engage. I don't hear an audible click, so unless I'm missing something, it isn't engaging during the self test.

"Here is a way to test the IPDM: Turn the ignition key to the on position, press your door switch 10 times, turn the ignition off then turn it back to the on position. If you do this right your horn will beep and the oil light will start flashing. The defroster ,headlights,cooling fans,wipers,and compressor clutch will cycle, so make sure that your hood is open so you can here the clicks of the compressor clutch. This is called the auto active test and this tests the main relays in the IPDM. If the compressor clutch clicks then its NOT the IPDM. Then i would suggest do what Jim said and test your pressure switch."

[EdBwoy]

The compressor clutch is engaged by an electromagnet circuit. The FSM might not go into detail on how to jump this, but I bet the connector that goes to the magnet can be fed power from the battery.
I can't remember if this is a single wire or 2-wire feed, so I'd recommend you check the FSM.

For the pressure sensor, I don't think that's a common failure point in Nissans, but outliers exist. Again, without going into the FSM, I believe it is a potentiometer (rather than discrete switch) and it reads progressive pressures from the refregirant. So right now it's reading zero (or baseline for the system) but if you jump/ ground it, it's going to go to max pressure and thus try to give you the most cooling... if you're still interested in investigating that.

Some obvious questions:
1. What is your ambient temperature and what's your set temp in the car?
2. Is the blower behaving normally in that it can still vary in speed?
3. What happens when you push "auto" inside the cabin?
4. What happens when you set the temp to either minimum or maximum?

It's pretty weird that the engine would idle higher even without the clutch engaging. I assumed the idle followed the increased load, not that it anticipated extra load. Gonna have to look into it sometime.

[M35Soup]

The compressor clutch is engaged by an electromagnet circuit. The FSM might not go into detail on how to jump this, but I bet the connector that goes to the magnet can be fed power from the battery.
I can't remember if this is a single wire or 2-wire feed, so I'd recommend you check the FSM.

For the pressure sensor, I don't think that's a common failure point in Nissans, but outliers exist. Again, without going into the FSM, I believe it is a potentiometer (rather than discrete switch) and it reads progressive pressures from the refregirant. So right now it's reading zero (or baseline for the system) but if you jump/ ground it, it's going to go to max pressure and thus try to give you the most cooling... if you're still interested in investigating that.

Some obvious questions:
1. What is your ambient temperature and what's your set temp in the car?
2. Is the blower behaving normally in that it can still vary in speed?
3. What happens when you push "auto" inside the cabin?
4. What happens when you set the temp to either minimum or maximum?

It's pretty weird that the engine would idle higher even without the clutch engaging. I assumed the idle followed the increased load, not that it anticipated extra load. Gonna have to look into it sometime.

Thanks for responding!

To answer your questions:
1. What is your ambient temperature and what's your set temp in the car?

The outside temp was around 70 yesterday, and a little colder today, and I set the car temp to 60, but played around with it as I was testing.

2. Is the blower behaving normally in that it can still vary in speed?

The blower works fine in max and min modes, and all the way through that cycle.

3. What happens when you push "auto" inside the cabin?

When you push auto, the blower lowers around 2-3 settings, decreasing the amount of air being blown into the car.

4. What happens when you set the temp to either minimum or maximum?

When I set it to max (coldest), it gets slightly cooler than warm, but not really cool. On Min (hottest), it will get hot like it should. No issues with it heating in both outside and recirculate.

As to the idle changing, it's definitely noticeable as if you were turning on/off the A/C. Would the fans draw enough to drop it?

[Six_Legs]

Final outcome on this?
My car just started doing the same exact thing last weekend. I took it to my mechanic to have him check the system and it appears that I will need to replace the compressor/clutch. He said there is power to the compressor but the clutch will not engage.
VERY costly repair with parts and labor as other components need to be replaced when the system is opened. Luckily I have 2 months left on my extended warranty so looks like I dodged a bullet on this one!

[Sstupid]

I had this same issue a couple of years ago. I just put a test light on the electromagnetic clutch wire after hitting the A/C button on the dash. Obviously, do not attempt this with the car running. If you have the 12V at the connector and the clutch isn't engaging, then the clutch is bad. If you have a bad clutch, like I did, go the DIY I wrote for replacing it. Hope it helps.

The connector is hard to. You can barely see it in the pic below. I unplugged it and put the test light on it.

[Six_Legs]

I had this same issue a couple of years ago. I just put a test light on the electromagnetic clutch wire after hitting the A/C button on the dash. Obviously, do not attempt this with the car running. If you have the 12V at the connector and the clutch isn't engaging, then the clutch is bad. If you have a bad clutch, like I did, go the DIY I wrote for replacing it. Hope it helps.

The connector is hard to. You can barely see it in the pic below. I unplugged it and put the test light on it.

Nice write up!!
I'm sure it's the clutch as I was standing under the car with my mechanic when he tested that connector.
I took the car to the dealer on Thurs as I still have 2 months on my warranty. My service adviser called me and advised that I also have a steering rack leak and trans. pan leak and that all will be taken care of under warranty!

[cruzad3r]

you lucky dog. that's a huge bill you just dodged! what kind of warranty program is it?

[Six_Legs]

you lucky dog. that's a huge bill you just dodged! what kind of warranty program is it?

I purchased an extended warranty from the Audi dealer I bought the car from. It was their Platinum plan, it covered everything and was a 3/36000 term. I will have to pay a $100 deductible and I'll be good to go.

Definitely lucked out on the timing and turns out it was money well spent!