A/C Diagnosis Help

sounds like the system is working right, for the high side reading see if a local A/C shop that can make you a small extension hose with r12 female and r134a male,
if not do you have a laser temp reader just check the condenser it should be around 200 to 300 degrees depending.

another thing is the compressor oil needs to be PAG 134a, r12 oil does not work well, also it is recommended that all o rings seals and hoses be replace because the rubber used for r12 will leak 134a (hoses in 134a system have a plastic inner liner), trying to chase a leak on a converted system is a nightmare i have found on some it was the Schrader valve and because you have the gauges on you will never find it.

running new hoses and replacing seals can take money and time, way more than a few cans of 134a every season

 

Well, you definitely need to get the high side on, in order to diagnose any pressure issues. Removing the Airbox nuts is easy with a 1/4" ratchet and extension (or deep well socket).
The conventional wisdom says that R12 hoses will always lose the 134a gas, since the molecules are small enough to permeate the hose wall. Switching to 134a without changing the hoses to barrier hoses means you will always be recharging the system at some point.

(I have my passenger gas tank out right now for a different issue, so I deciced now's a good time to run new AC hoses in the passenger side sill up to the front of the car. The other hoses at the front of the car are super easy to get to and change.)

 

If you have the original AC hoses, I think you will find they have a permeability issue and will leak freon. I recommend the hoses from Vintage Air.

 

Agreed with the folks above. I've gone through this with adding a whole new system to the car.

It's so INCREDIBLY easy to have a leak. One little o-ring can do it. Old hoses... definitely would do it.

You could have a leak in the evaporator... I doubt it... but it's possible. And if its leaking from there I don't think dye will help you out.

If it were me (and it was) I would yank that York compressor out of there, put in a Sanden that doesn't weigh a ton like the OG one and run all new lines.

You can even replace the switch (if you like) to a new-style switch and ditch the capillary switch as well... but if the switches work then no reason to.

If you REALLY don't think you have a leak, pull vacuum and leave it pulled overnight.

If you still have vacuum in the morning (at the same place) then you don't have a leak.

 

So next step - is the clutch working

With the car off, I could rotate the clutch by hand.

Then I put a thermometer in the vents. It showed 93.7F.
Then I started the car, put the A/C coldness setting to the middle, turned the fans on high
Checked under the car and.....

but do you hear the CLUNK when AC cltch engagaes or disengages?;

If there is a belt to engine on AC clutch, HOW were you able to rotate it?
When you apply 12V to clutch wire does it make a big sound?

 

Yep you should hear it clicking.

 

Guys, I think you are missing something. He said in post #1 that he has 104 psi static pressure. That would indicate a sufficient charge. The system may leak over time but that does not appear to be the issue. He then said after starting the AC the low side pressure was 28 psi. That's too low and would indicate things like a bad compressor, bad TX valve, or some kind of blockage on the high side. It also indicates that the compressor is "trying" so not a clutch issue. Need to know what the high side pressure it. If it's in the ball park it would say the compressor is ok and probably one of the other issues. But even with a low side of 28 psi it seems odd that he is not getting any cooling.

 

The static pressure does look ok. Suggests a gas temp of around 31 deg C. Was this similar to the air temperature around the system?
There is a gauze strainer on the expansion valve inlet.
Chances are that this will be partially blocked if its never been cleaned.
Mine was full of crud that caused erratic cooling.
With the static pressure you have, If the system is working at 28 psi suction pressure, the condenser fans are running and the compressor suction line is not cold I would check this gauze strainer.

 

The static pressure/temp balances with the air temp, so you have enough refrigerant in the system for the system to provide some cooling. And the low pressure when operating confirms this.
In one of your pictures you show a sight glass in the top of the receiver. This is a service aid to determine that the system is adequately charged and therefore feeding the expansion valve with liquid refrigerant. When you run the system is this sight glass either completely clear and full of clear liquid, frothing with white bubbles, or is there just what appears to be gas passing through it. Also, is the compressor suction line cold, or not, when running the system. These two indicators can you tell you a lot about what is going on, and whether you have a blockage or loss of gas. The condenser fans should be running almost constantly @ 34c on these cars, when the vehicle is at rest.. If not, the system is not rejecting heat, therefore not cooling properly. Another pointer as to whats going on.