At Least the Evaporator is Apparantly not Leaking

Well, about a month ago, I noticed the air in my '88 300E to not be cooling very well. This worried me, afraid of the infamous evaporator problem. I had never had to add refrigerant, so I just hoped that it was a tiny leak that had lost the refrigerant over the period of many years.

I charged the system, probably added a little more than a pound. I drove the car and got vent temps below 40 degrees. I was VERY satisfied, and wishing for a sweater. I also put in UV dye at that time.

I had not driven the car until a few days ago and then drove it to find that the vent temp is only getting down to about 52, best case. I worried that I had a bad leak and got out the black light. I went over it THOROUGHLY and could find no leak anywhere. Today, I put the gauges on to see where I stood. I STILL had the same pressures I had when I charged it. It is making condensation drain like Niagra Falls so I am convinced that the refrigeration portin is working well.

This means that either a flap under the dash is not working properly or the climate control is calling for coolant. Possibly the heater valve could be seeping a little coolant through I suppose.

Well, anyway, I have been SOOOOooooo lucky with this car to have never had to do anything to the a/c. I am really glad that I have no bad leak.

Are any of you intimately familiar with the climate control et al? Can you suggest anything? The temp sensor blower is working. The blower motor is blowing well and all the vents are putting out cold air, it's just that the air is not as cold as it should be.

BTW. My pressures are: 28 low, 275 high, about 52 or 54 vent temp.

Thanks,