A/C system

[Dblake]

Hi, I’m new here and need some opinions. I have a 1993 Mustang GT. The car sat for about 6 year and I’ve restored the car and I’m trying to get the A/C system in tip top shape. I replaced the compressor and the liquid line because the line melted on the header. With that said, once the system was charged professionally, the high side is building too much pressure. The last thing I want to do is fry up a new compressor. Also the compressor is constantly kicking on and off. Plus I only have air coming out of the foot vents and defrost vents. I’m sure that is something to do with a vacuum leak. I just don’t know where to go from here. Anything helps! Thanks in advance

 

[Dblake]

My 1993 GT has factory installed air conditioning. The compressor froze up and so I replaced it along with the liquid line because it melted on the header. My question is why is my high side building too much pressure? System was filled by a professional and he is stumped by it too. Anything helps! Thanks in advance.

 

[Mustang5L5]

What pressures are you getting on high/low side?

Usually a high differential pressure could be due to a clog in the orifice tube restricting flow.

 

[General karthief]

Funny, your professional can't tell you whats wrong?
i agree with mustang5L5.
and check the plastic vacuum line that runs from the tree across the firewall to the passenger side and the hose under the dash has a connection too.

 

[Dblake]

What pressures are you getting on high/low side?

Usually a high differential pressure could be due to a clog in the orifice tube restricting flow.

The orifice tube was replaced as well. I’m not sure what he said the exact pressure was on it. I was just told it was way too high.

 

[jrichker]

The orifice tube was replaced as well. I’m not sure what he said the exact pressure was on it. I was just told it was way too high.

Too high pressure means 1 or more of the following problems.
1.) System was not properly vacuumed down before being recharged. Air left in the system will cause high head pressure.
2.) System was overcharged when using R134 refrigerant. The specified charge for R134 is 80% of the R12 refrigerant 32-36 Oz charge. That's about 25-28 Oz of R134 in a Fox body Mustang.
3.) The orifice is clogged due to one of several causes: failure to flush the system of the old oil if aR134 conversion was done. The mineral used with R12 does not mix with R134 and tends to drop out of suspension in the refrigerant at low places in the A/C system The orifice tube is clogged due to dirt and debris in the system.
4.) Insufficient airflow through the condenser, especially during low speed stop and go driving.