300SD parallel flow cond results
 

I had a new R4 compressor, parallel flow condenser (24 1/2 X 14"), dryer, 28 oz R134 (vacuumed first), and exp valve put in at a local ac shop because I was tired of 50 - 60 degree air at the center vent. The results are that I now have constant 50 degree air at speed and 80 degree air at idle on a 90 degree day with blower on high speed. Not much improvement to me. The condenser seems to be to small because running water over it at idle makes the air go down to 50 degrees from 80. The elec condenser fan is on all of the time. I don't see how a larger cond will fit because of the 90 degree turn the hose must make. Anyway, so far I haven't done any good after about $700 spent. The guys at ackits, where I bought the parts, were not helpful at all. They sold me a 26 X 14 cond first but it wouldn't fit so I reordered a 24 1/2 X 14 which fit nicely. We're on a trip now so I can't do anything till we get home next week. Oh yeah, the ac control module quit working, so now we have no air at all. I'm hearing words from my wife that I didn't know she knew.

28oz? I thought R134 should have around 38 with a parallel coil...

I think it's 35 oz of R12 so 80% is 28 oz. Is this not correct? 85 300SD

Can't be. My W123 takes 2.6lbs R-12, or 41.6oz

I don't have the numbers for the W126, but it's gotta be more.

2.9 lbs. of R12 is on my tag; can't believe yours would be much different.

80% is a starting point for conversions; it's not cast in stone. Some use more, some less. Pressures at 1500 rpm help tell the story on conversions, particularly when a major component is changed.

I,too, have a parallel flow condensor in my 300SD..15.5" X 24.75". I worked hard to make those hoses!!


I'd add 10-14 oz. more R134A (slowly) watching pressures and vent temps.

You have a custom system, and so the quantity specification isn't of much use. I would suggest using a set of gauges and trying to match the proper high and low pressure side readings. I'll bet if you get gauges on it you'll see that the low side pressure is running too low due to insufficient freon.

Ken300D

Did the R134a conversion in the 82 300TD with a parallel flow condenser. Went back to R12 due to bad AC temps. Works fine now. Stop wasting your money and keep the system R12.

Dave

Ditto. You have too low a charge.

I am waiting on my vacuum pump to arrive before I update my thread. I am planning on putting in around 36-38ozs (as a rough estimate, of course the pressures and temp drop being more important).