K, I flipped a bill today and took the chance of wasting some money recharging the ac on my '90 240. The tech said there were no obvious leaks in the system, which is good, but once it was fully charged the temp of the cool air was only about 55-60 degrees. He assured me that the normal reading should be around 45 and that there might be some issue with the system. Does anyone have any ideas of what would cause a decrease in efficiency of this system once fully charged?

I'm heading to Phoenix tomorrow for the weekend and am dreading the idea of ac that doesn't work well enough to keep me relatively cool, not that I'd be able to address the issue before I head down, but since I'll be making repeated trips down this summer I'd like to fix it eventually.

All ideas welcome. Thanks!

 

I believe '90 used the old R12 and unless it's been retrofitted for R-134a it's not going to work.

According to Larry Carley
"It's important to remember that R-134a or any other alternative refrigerant cannot be mixed with R-12 or used to top off an R-12 system. This is an absolute must to prevent cross-contamination of refrigerants and cooling performance problems. R-134a and mineral oil won't mix. So if somebody recharges an R-12 system with R-134a and doesn't add a compatible ester POE lubricant, the compressor will soon fail"

 

first off, where are you? it sounds like you are in AZ. Second, if there are no leaks, and the system is working as it should, then look to the condenser and the evaporator. Clean the coils. especially the evaporator. remove the blower and vacuum and spray out the area. It also could be that you have a blend door open.