Half @$$ cold AC

Zack.

Has been dubbed Arnold
Supporting Member
Location
Livermore, CA
My AC has started being only cool not cold. The refrigerant pressure is good, at least according to the gauge on the diy refill bottle. Fan seems to be blowing okay as well. What else am I looking for?
 

Muadeeb

Nissan al Gaib
Admin
Location
Dallas
Engine coolant level, and make sure the clutch is engaging. Not sure on the 2nd gen compressor, but on the first gen the entire face of the pulley would disengage from the pulley when the clutch disengaged.
 

josx2

Bought an X
Supporting Member
Location
Mebane, NC
ENot sure on the 2nd gen compressor, but on the first gen the entire face of the pulley would disengage from the pulley when the clutch disengaged.
yup....that's how ALL ac compressors operate ;-)

if it's engaged @Zack, you'll see the face of the pulley rotating with the pulley/belt. when it's disengaged, the face will remain still while the pulley spins freely. It'll cycle on/off if it's working properly.
 

jsexton

Need Bigger Tires
Location
Lewis Center, OH
Wash out the fins on your ac condenser and radiator with water.

Mine get really clogged up from off-roading. Washing it out always makes a big difference.
 

Zack.

Has been dubbed Arnold
Supporting Member
Location
Livermore, CA
yup....that's how ALL ac compressors operate ;-)

if it's engaged @Zack, you'll see the face of the pulley rotating with the pulley/belt. when it's disengaged, the face will remain still while the pulley spins freely. It'll cycle on/off if it's working properly.

So just now on my way home from work I noticed cold air coming from the vent. My AC switch was not on. I cranked the fan up and cycled the switch between on and off periodically the rest of the way home. It stayed ice cold. When I got home I left the engine on with AC switch off and opened the hood to see the pulley spinning, face and all. Is it pretty safe to assume I need a new compressor at this point?
 

Zack.

Has been dubbed Arnold
Supporting Member
Location
Livermore, CA
Defrost was on originally but I changed it to the face vent setting when I realized it felt cold
 

jsexton

Need Bigger Tires
Location
Lewis Center, OH
I don’t believe the ac ever kicks off after the defrost has been on until you actually turn the ignition off. Dumb

Might want to take a look tomorrow after not having the defrost on at all to see if it acts the same.
 

TerryD

Total Tease
Supporting Member
Location
Covington, Va
I don’t believe the ac ever kicks off after the defrost has been on until you actually turn the ignition off. Dumb

Might want to take a look tomorrow after not having the defrost on at all to see if it acts the same.

I've been able to defeat mine by turning on the A/C in vent for a little while then turning off the A/C. Seems to work on my 07. Haven't timed it to see how long it takes though.
 

Zack.

Has been dubbed Arnold
Supporting Member
Location
Livermore, CA
I don’t believe the ac ever kicks off after the defrost has been on until you actually turn the ignition off. Dumb

Might want to take a look tomorrow after not having the defrost on at all to see if it acts the same.


Okay so this morning started up with AC off - pulley face not spinning. Pressed AC button and pulley face started spinning. Drove most of the way to work with it on and it felt like it was blowing colder than it had been, but not quite icy. Turned it off the last few miles and it stopped cooling.

So defrost thing confirmed, but still unsure why it would have been blowing only medium cold the last couple weeks.
 

29erClan

Bought an X
Location
Meh
When you checked it with the recharge bottle gauge was it running, set to max, and cycling the compressor on and off? You may have to watch it a few minutes.

What I'm getting at is the pressure looks fine during one part of the cycle while there's enough running through the evap that the compressor is off. If you are only a little low on 134a it'll kick the compressor on/off every 2-5 minutes, (depends on temps that day), and if very low it'll cycle on/off every 10-15 seconds. I have a video of the gauge needle bouncing around like this somewhere.

The compressor seems to be controlled by high and low pressure sensors like an air compressor tries to keep the tank in a certain pressure range. Failing to stay in range could be either sensor or the clutch activation stuff. Besides a bad compressor, leak, etc..

In my case the valve core was loose and I had a slow leak I couldn't find anywhere else. A normal tire valve core tool to tighten it about 1/4 turn, top off from the refill bottle while watching the pressure gauge during the whole on/off cycle, and it's been fine for 2 years or so.
 
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