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This can be done, but may not be for the faint of heart
If you are going to try the change over, I believe the best way to do this is to pull the entire old system out and put the entire donor system in. Every hose, fitting, and every electrical connection under the dash. Well you need to get a new dryer and a full set of new o-rings. You may have to think through installing the controls off the newer unit if it has the already mentioned Blue Switch. But it should be possible to get it in there and working. The caveat is it will also be a lot of work. That year is supposed to have improved performance. Hose routing is better but also very different.
You do not however have to go through all that to get a AC system running well in an older 240.
If you can still get hold of it, you want that pusher fan out of the 91 model. Installing the pusher fan in a converted R12 system that is one of the best ways to improve system performance at idle or slow speeds. I used to pray for the light to change after the first conversion on Inga when the temps hit the 90's. That was with Ester and R134 and that was not a good combo at all. Actually installed a combo of R12 and Freeze 12 in with the Ester. Actualy worked really well right up until the compressor locked up, and not sure if the two were related or not.
Replacing the compressor with one out of a 90's model, flushing the system out, installing Pag 40, changing out the expansion valve, and charging her up with R134 works pretty dang well.
One other thing I found is to not believe the pressures called out for R134 systems, those are for unconverted systems. My gauges suggested a low pressure of 45 psi and that is what I charged the system up to, and the performance was disappointing. Guy at work suggested lowering the pressures a bit played with that and found out that makes a big difference.
Now run the system at 36 PSI on the low side. With the pusher fan running, outside temp of 92 degrees, engine idling at around 900 RPM, and there is 43 degree air coming out of the vents. It was more like 50 something degree air with a low pressure of 45 psi by the way. Now to be fair Inga did not have the pusher fan, a belly pan, or a swamp cooler (AKA Tropical Fan Clutch) installed when the system locked up. All that was put in place before the start of this last summer and after replacing the compressor and other bits. All of it makes some difference I am sure. Have to also toss in adding the Refletix to the roof, but that is a wagon thing not needed on sedans.
Bottom line is you can in fact stay very comfortable in 245DL converted over to R134 without changing it all out. And I mean very comfortable south of I10 in Gulf Coast heat and humidity. With the temps in the mid 90's about a 1/4 of way my 32 mile drive home, the knob is over in the middle and the fan on 2.
How do you know that you have issues with the Condenser by the way?
Regards,
Paul (AKA Ducky)
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