What should the AC pressure read at the low side valve with engine off?Mine read 90 lb
With engine running,mechanic filled witn R 406A to 40 lb suction pressure,is it OK.Car is cool again.
Many thanks for info

Pressures are usually only checked while running. What kind of refrigerant is that? I've never heard of it.

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Benzmac:
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

On the bottle in English and French,this is Canada you know says R406A,drop-in R12 substitute or something to that effect and EPA approved,something or others.

R406a is an approved R-12 replacement refrigerant composed by weight of 55% R-22/ 37% R-142b / 8% R-600a. It cools very well and has similar operating pressures to R-12.

The suction pressure is dependant on ambient temperature, relative humidity, engine rpm, etc. 40 psi suction at idle/80f ambient temp. sounds okay. I usually operate engine at 2,000 rpm for 60-90 seconds A/C blower on high and look for 22-30psi at 80f with your model car and R-406a. Under the same conditions, duct discharge temp should be less than 45f.

Hope this helps.

Hatch


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1980 240d 4sp
ASE Master Auto Technician
ASE Advanced Engine Performance

Thank you very much ,Hatch.Seems like I got a safe alternative to R12 then.


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Tom 1992 300E 2.6