I have a 1993 LT1 and in the last few years it has been necessary to add refrigerant about every 9 to 12 months to the A/C system. The shop that has been doing the recharging finally said they found the leak in the evaporator tube. They replaced the evaporator tube, recharged the refrigerant and completed the job. Now they say the pressure readings on the A/C system are not correct; the system does not blow cold air and the compressor is bad.

The car has always blown cold air even when the refrigerant was low up to and including the day I took the car in to get the evaporator tube replaced. Even with the outside temperature not being very hot now, the A/C system blows hot air with the temp setting on 60 and I can tell a big difference from the way it was working before they did the work. I have my opinion, but I want to check if anyone knows what they think may have happened. Did the compressor just suddenly go bad after they opened up the A/C system and did the work or did they do something wrong causing the problem. They said they used the proper R-12 refrigerant. The shop is a chevrolet dealer and has an experienced corvette technician but has made some mistakes on other repairs to my car lately.

 

My opinion, but I think they blew it.

 

Get a second opinion , then react accordingly

 

First, disconnect and reconnect the battery to remove any a/c trouble codes logged in memory. Then remove the Blower Module or Resistor Pod on the Evaporator Case and look inside to observe the Temp Door. Have someone operate the Controls between 60 and 90 or Cold and Hot. The door should move. If not, the motor (electronic air) or cable (manual air) that moves it isn't doing it's job. Otherwise, post the pressures the shop obtained or hook up a scanner and get the static pressure (a/c off) from the Pressure Sensor and then the high side from the same Sensor with the Compressor engaged. Finally, feel the big pipe where it exits the Evaporator (up top) and the smaller pipe (down below) right where it enters the Evaporator. Both should be cool and below ambient.

PS - I don't know what the shop meant by an Evaporator Tube - The Evaporator is one part with an inlet and outlet connected/joined to separate lines with a couple of nuts with o-rings to form a leak proof joint. Did they break the inlet or outlet?

 

I'll ask the shop about the pressure readings because they are going to take another look at it. I bought the A/C evaporator tube (part discontinued and the name is in the 93 factory service manual) because the shop said they found a leak from the service port on that tube. I'll also have the shop check the temp door.

Thanks for your help

 

Maybe they mean the orifice tube. Also, I wonder if in all this recharging they ever added any oil?

 

For future reference the high side service port on my 93 evaporator tube was leaking too, I found a kit at NAPA that allowed me to replace just the port, not the entire tube. If you look close you will see it can be unscrewed from the tube.

 

I have replaced faulty service ports before on the high side(the shrader valves go bad over time and leak). I do not think that the low side port is servicable.

 

You are right that the low side port itself is not removable, however unlike the high side you can replace the shrader valve which is the part that usually fails.

 

Just had this done on my vette on the high side. I did not have a vacuum pump at the time. That valve is a piece of junk and gets replaced all the time. The ball (supported by a spring) gets old and hard and changes shape. Then if disturbed it will not seat again properly. Easy money for the A/C shops, just screws off. My Silverado has the same problem and needs to be changed.

The low pressure port seems to be more substantial and not a problem.