A/C Problem Ideas?

[RedX]

Just want to post my A/C woes here. I'll try to be a specific as possible.

At various times (not always mind you – in the morning all is good, when the X has cooled overnight), the A/C just refuses to work. You can hear the compressor kick on for about 15-20 seconds, then shut off again. And it stays off for several minutes. Then it may or may not come on again with it's tell-tale thump. I verified that this, in fact, is happening by opening the hood and watching this little progression of events. All the while the interior is never really cooling.

I took the X in today to my dealer to have this looked at, and of course, they popped some more refrigerant into the system, and gave it the "All's well" verdict. I explained that compressor cycles on and off, never really cooling the interior, to the response of "uh huh." So when I went to pick the truck up this evening, the A/C worked well....for a while. But on the way to dinner, the compressor started dancing it's little jig again, never really cooling the X off inside. So I will go back tomorrow and get them to look at it again.

I am just posting to see if ANYONE knows of any possible reasons why this is happening. Is there a relay that could be intermittently opening and closing (there really seems to be no rhythm to the cycling on and off)? All the A/C related fuses look good. Could the compressor be bad? I know the refrigerant level is proper (was just recharged today with dye put into the system to pinpoint a leak – I see no leak of refrigerant).

I'm at my wit's end...and my dealer is rather lax in helping resolve the problem. But the extended warranty does cover the A/C, so I will continue to have them look at until it is fixed. But with the temps around 95 degrees, and a pregnant wife riding around with me, my awareness of a non-operational A/C ststem is becoming painfully apparent. I just wanted to see if anyone knew the workings of the system well enough to give me some pointers why this thing is not working in the manner in which it is (or is not).

[ScottG]

I think it's leaking somewhere and you just haven't found the spot. Low refrigerant will cause the compresor to cycle as you are describing.

[OffroadX]

Of course if it's too low it won't work, but your typical "low" refrigerant usually causes the A/C to get too cold and the evaporator will ice over and block the airflow. At least that's how it happens in a home A/C where the thermostat is inside away from the condenser and its job is to turn on the compressor when the temp is above the set point. On an auto A/C system, the thermostat is right at/on the evaporator and its job is to keep the evaporator from getting to 32 degrees and icing up, the temperature of the cabin is adjusted by how much of the ambient air bypasses the compressor.
If the refrigerant were low, the condenser would be on the verge of icing up almost constantly after the first time the compressor kicked on and brought the condenser down to the low 30's. The compressor would probably cycle oddly, but I would expect the air to continue to be chilled.

I'm no HVAC tech by any means, but if they just dumped refrigerant in without actually testing the pressure on both sides of the system, they're not following procedure.

Brent

[ScottG]

I think you are wrong Brent, every vehicle I have ever owned that was low on freon blew hot air. It could be leaking behind the dash or from inside the compressor and the dye isn't visible. I had a GMC truck that was leaking behing the dash, and it was a bitch to find the leak. It was leaking from the radiator looking thing behind the dash. I think it's called the evaporator coil?? I'm not familiar with the Nissan system, but I replaced just about every A/C part on my GMC when I was trying to find the leak.

Luckily RedX's truck is under warranty!

[rednec]

RedX found out it was a faulty pressure switch and it is now on order from his local dealer.

Has anyone else had a problem with the "High Side" A/C hose leaking. I know of 3 cases of this so far and wanted to see if it has happened to anyone else. Mine is currently leaking and of course I'm out of my bumper to bumper warranty. I talked to my local dealer and he said he's seen a few come through and thought that they redesigned the line. I've been depating on spending $65 for a new line from Nissan or spending $25 on a used line from a junk yard.