I am converting my 84 300DT to 134. I have a new compressor, receiver/dryer, and expansion valve. I also bought a vacuum pump and manifold for servicing.
Do I absolutely have to use compressed air to flush the system? Can I just use the flushing chemical and then suck it clean with the vacuum pump? I don't have an air compressor. I would have to buy one for this job.
Thanks

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1984 300DT 302,000 miles
1991 300SE 197,000 miles