2000 Maxima AC not working, AMB reads -22

[jackofalltrades1980]

The AC system on my Maxima doesn't work. When the climate control is switched to the maximum settings (temp dial set to 65 degrees, fan on max) nothing happens, the clutch doesnt cycle on. Thought it needed R134 but system wouldn't take any in after a short burst. Even when I cycled the clutch on manually through the relay, instead of the system working, it popped the valve on the high side like a pressure relief. After doing some research I ended up changing the accumulator and the expansion valve, pulled vacuum and attempted to recharge with the same results, the thing will take a little from the can on the low side and that's it. The compressor won't cycle on, no more 134 moves through the system. If I cycle the compressor on, it'll be the same thing, it won't suck any more 134 in and will pop that pressure relief on the high side after a short while. Also the condenser and the line will be pretty hot all the while. Now if I leave the compressor on and let the pressure balance out to where the thing doesn't pop the high side valve, I'll get some cool air, not blowing snowballs out the vents but some cool air. I then have to drive the car around to get airflow through the condenser to dissipate the heat in order for the slightly cool air to continue to flow otherwise that will stop because the heat isn't being dissipated from the condenser. Since the computer doesn't know the AC system has been cycled on, it won't cycle on the cooling fans until the engine temp goes up to the point that calls for the fans, which surprisingly isn't that often. The main kicker here with this problem is on the climate control display, if I hit the AMB button, it displays -22 degrees. I changed the AMB sensor with two different sensors from the junkyard and still get the same reading. I don't know if the computer is intentionally keeping the AC off because it thinks its subzero outside or if there's some other issue going on. There's really not much else I can think of trying on this system and its ticking me off big time.

[NutriaforBreakfast]

What is the PSI on the high side and the PSI on the low side of the compressor?

[jackofalltrades1980]

pressure is 25psi on both sides, system wouldn't take any more 134 above this.

[NutriaforBreakfast]

Theoretically your compressor is dead

Or there is a blockage or it is all leaking out

A vacuum pump and gauge would confirm this

[jackofalltrades1980]

The compressor will cycle on if I jumper the contacts on the relay terminal block, and with it running it will compress enough to make the condenser and the high side line just coming out of the condenser become kind of hot. It also builds up enough pressure that above a certain amount of 134, the high side line will pop like a pressure relief valve to bleed out the excess 134. I put a vac gauge on the thing and pulled vac and all that checked out and the system took one can of PAG oil with 134 and probably a little under a full can of straight 134. Expansion valve and accumulator were replaced as well. System will moderately cool if the compressor is manually cycled on and I drive the car to push air through the condenser to dissipate the heat. Now the only other thing I hadn't changed is the accumulator switch, but the thing I'm still wondering about is that climate control module reading -22 degrees on the AMB sensor. I wasn't sure if the computer will try to cycle on the heat instead of the AC when it thinks its -22 outside and the temperature is set to 65 degrees. Since the climate control module doesn't have a dedicated AC switch or heat switch, its going to try to raise the temp from what it believes it is, which might explain why I'm getting mediocre air because its mixing with heat from the heater coil just as well. I'm wondering if anyone had similar experience with this.

[NutriaforBreakfast]

Did you put in the recommended amount of PAG oil ? If there is too much oil and not enough
R134a the AC wont work right.

[jackofalltrades1980]

I put in the small can you normally get from autozone/etc and a little 134, still no good. I'm still wondering about that AMB-22 on the climate control though, and the possible confusion to the computer making it want to turn the heat on instead of the AC since there is no actual "AC on" setting on the panel.