a/c condensor efficiency?

I would like to know if there is a way to check the condensor efficiency of my 134 converted 2.3-16. At idle, it cools ok with the temps outside around 95 F. When moving, the temp gets a bit colder. Can the r-12 condensor be less efficient? Does a new 134 condensor have more cooling fins across the tubes? And does the expansion valve need to be changed to a 134 expansion valve? What, exactly, is the difference in the two expansion valves? Thanks, Joe

The condensor efficiency will have a minimal effect, in other words there is little difference in the most and least efficient condensors. It's capacity that counts, and that can only be significantly changed by putting in a larger condensor.

When changing over my 240D I put in the R134a expansion valve. Later on it started leaking and I replaced it with a new R12 unit that I had laying around. I could tell no difference in the two. I expect that the R134 actuates at a slightly higher pressure.

Good luck,

[engatwork]

An observation and an idea. On my 1985 300D that has been converted to r134 I get air out of the vents that is approximately 30 dF lower than ambient. I noticed the other day when it was raining and about 90 dF outside that I was seeing about a 48 dF drop (getting 42dF out of the vents). I am seriously considering using my windshield washer reservoir/pump and reworking the piping to spray water onto the inlet side of the condenser in front of the radiator to increase the performance of the a/c system. I would not run the pump continuously. My concern would be minerals precipitating out of the water and plugging my condenser as it is evaporated on the coils. I do not use the windshield washer and that 42 dF air sure felt good coming out of the vents.

If the a new condensor isnt the cure, can anyone guide me on how to check the fresh air door under the cowling? Many references have been made to the dor/flap. Can it be accessesed thru the interior? Is the whole mechanism located near the glove box? Thanks, Joe

I get an interior dash temp of 56 degrees with an ambient temp of 95 and humid. There are no leaks at all. 134 converted 190 16 valve.

[engatwork]

Joe - I don't know if this is going to answer your question or not but I have been researching on how to improve the efficiency of my a/c on the 1985 300D that has been converted. I was talking to a guy from a company that builds/supplies a/c systems to old cars (VintageAir) and he said that I should be able to get 42dF air out of my converted 300D with the original components. He said the procedure is to evacuate/vacuum the system, put a big shop fan blowing into the radiator area, add 1# of 134 and then add 1 oz at a time until the temp drops to 42 dF out of the vent. Yesterday afternoon I stopped by my a/c techs shop and asked him to put his gauges on it. He did and the low pressure would drop down below 40 psi BUT the whole time it was swinging back up to around 50. He said that this is an indication that the expansion valve is not "settling" down after which time I ordered a new expansion valve (thanks fastlane). Anyway, in discussing how to improve the system he said that increasing the condenser size will probably not help a whole lot. I am working with him to get the new expansion valve in and will see what happens then. Currently, it only gets down to around 65 dF out of the vent - this is with 95dF outside air temp and 100% recirc. I will keep ya'll posted.
I would assume that you should be able to measure condenser efficiency by looking at the pressure/temp in and out of the unit and then going through some calculations on the a/c curves. It has been along time since I have done this. You may want to try to find a good local a/c tech that can help you in your town.

I asked this question before. My 1986 16 valve has one aux fan mounted in front of the condensor. Has anyone converted this fan to the two fan setup of the 2.6? I have read that the two fan cars take better to the 134 conversion than the single fan cars. What has to be done to convert to the dual fan setup: switch, mounting, wiring, etc. Thanks, Joe