Auto Air Conditioning & Heater Repair: air conditioner doesnt work if its in the sun, aluminum tubes, toyota corolla

Question
I have a 1995 Toyota Corolla. I have a very strange problem with my air conditioner. If I have my car in the shade or it is in the cool of the morning my A/C works great and blows freezing cold. If I am parked in the hot sun with no shade it blows hot hot air. We have added freon and that does not help so it's not a leak. Plus, if I am parked in shade the air conditioner will work for quite a while but driving in the hot sun for long periods of time it will start wearing off and start blowing hot again. What could this be? Thank you

Answer
HI,

 I had to think about his one for a while and check with some information at work to see if there was a sunload sensor in the circuit to which there is not.  Some cars take outside references and some do not.  To my recollection the Corolla is pretty basic so lets see whats going on.

 What I want to know first is what is going on when the system in not functioning properly and we can work back from there to figure out why its shade/sun related.
 When the system stops cooling the air I want you to pull over, pop the hood and take a peek at the compressor and see what it is doing.  

Is it cycling on and off quickly
Is it running all the time
Is it not running at all.

 ONce you have determined this follow the two aluminum tubes into the passengers compartment.  One is larger than the other.   Put your hands on them (by the firewall) and tell me what they feel like (temperature wise, I already know what aluminum feels like :)
 

Wayne