Back on the cleaning the condensor, mine wasn't cooling as much as I thought it should have been. I looked under there and saw some small rocks but not as bad as I expected. I purchased an air-wand from Harbor Frieght for like $4.95 and proceeded to blow outward from between the condensor and radiatior. I then did the same from the inside of the radiator. When I was done and swept up the debris, I was surprised at the size of the pile of rocks that came out. This simple repair worked real nice as the HVAC then worked real good after that.
With R134 systems, there is a low and high pressure switches that will cut off the compressor to save it. I don't know anything about the high and low pressure sides other than the obvious; one is suction and one is pressure and there should be a distinct difference. If the compressor starts coming apart internally, it will plug the orifice and cause the issues as well. I did end up replacing the compressor on mine at 260K miles or so when the clutch pulley bearing started making noise. At the time, it still worked just fine as far as cooling capability.

 

Hi dgrant, most of what you say is true, a dirty condenser will inhibit good performance of the AC. It will cause high pressures on the high side, and raise the low side readings as well, it could get high enough on the high side,(410psi), to trip the pressure safety switch to shut down the compressor.
Where you are a misunderstanding the process a bit is saying that a plugged orifice can cause the issues the op claimed,(high low side pressures and wimpy ac performance). A plugged orifice will do the opposite, it will inhibit the flow of refrigerant, causing the suction,(low), side to have lower pressures because the compressor is still creating suction, but no refrigerant is able to come through, and can go so far as to creat a vacuum condition on the low side and a very low reading on the pressure(high) side. This would also cause the low pressure switch to trip,(30psi), and shut down the compressor to protect it from self destruction from lack of lubrication which is carried through the system by the refrigerant. In the NON Cycling system as on the vette, there is only one safety switch which serves the dual role as both low and high pressure monitoring. There is also a High Pressure blow off valve on the compressor to further protect the system should the High pressure switch fail.
So to summerize,
1,You are absolutely right about the need for a clean condenser.
And the other possibilities are
2, overcharging, which the op has rulled out.
3, Air and wrong chemicals in the system, also ruled out.
4, Broken , but not clogged orifice tube, I personally have not seen that happen yet, but it is a remote possibility.
5, High speed fans not actuating with the AC on, which at some point on a really hot day would trip the High Pressure switch to cycle off the compressor.
6,Bent or broken valves in the compressor.
Unless I've forgotten something the above are pretty much the only reasons for the op's symptoms
Luck To All.

 

I'm sure you are correct. I'm not an HVAC expert by any means and don't claim to be. My thoughts are that the OP should take his car to someone who is an expert on them and have the system checked out for all the things you refer too. I had an '01 Xterra which was running weak as far as the HVAC system goes. I have the guages too even though I don't know how to use them properly. I did add a can of refrigerant to it which caused an over-pressure problem. I ended up paying $50 to a local place to evacuate and re-fill the system properly to which it worked perfectly after that.

 

OK. Regarding a Plugged Condenser... I'm convinced that I need to do something better than my quick look at my condenser.

The "wand" was something which is run by an air compressor I presume. Correct?

Mike

 

I bought the air wand at Harbor Freight for like $4.95. Since its lost in my garage somewhere after a move, I needed to clean out the condensor again (once a year), so I fabricated a similar setup with copper and a hose connection and used water to do it. After a year since the last time, I got another pile of rocks out of it.

 

Help me with one thing... I thought the condenser was set tight against the radiator. How am I to get in there to blow the stone & debris out?

 

Take the cover off the top of the area and you will see there is a gap between them and the wands will fit in there real nicely.

 

Theres a 3/4" void between the condensor and the radiator! Ive seen grass growing in that GAP!

Clean your condensor & radiator and see if that helps. Thats the FIRST step..

BC