I browsed the forum topics, but couldn’t find a way to search them, so please forgive me if this question is redundant.
I just flushed my A/C system with Hecat Flush, replaced all o-rings (assembled with Nylog), replaced the compressor (used new seals), receiver/drier, expansion valve and the short hose that goes between the condenser & receiver/drier. I added the appropriate amount of oil upon assembly, and took it to the shop to have it charged with R12.
The shop said it held vacuum well and that the compressor was working properly. The pressures for the R12 are according to spec.
When the car is cold, at start-up, the A/C blows very cold. However, once the engine reaches operating temperature (approx. 80-86 degrees or so) the A/C starts blowing hot UNLESS you up the RPMs to around 1200RPM. Then it will blow cold all day long. In other words, I drove at highway speeds for over an hour and it never blew hot. As cold as could be. So much so that it gave me goosebumps and was uncomfortable for my hands.
I have checked the vacuum pump, and I have 20" at idle. I have also checked the pods under the dash that I could reach (I found 4 of them) and they all held vacuum fine. I also checked the fuses, and they all seem fine and have been replaced recently with similar metal fuses (I ditched all the aluminum ones.)
Any ideas of what the problem could be? It seems like such specific symptoms that I figured that someone here may know the problem, or at least point me in the right direction.
My wife will be driving the car about 1500 miles in a week and a half, so I am hoping I can have it solved by then. Any suggestions are greatly appreciated!