I don't know much about AC systems, but the pressure sensor has gone bad on my '87 300D and I need to swap it out. Do I need to get a new Dryer too or can I reuse the old one?

Thanks,

G

The generally accepted industry standard rule is that if you open the system you replace the receiver dryer... that is because the cost of the detrimental effects of moisture combining with the refrigerant and oil making acid....and that acid attacking the inside metal areas of the AC system.... making flakes come off into the fluid stream.... and clogging up something like the Txvalve..... are so much higher than the cost of the new receiver dryer it is not worth the chance of it having reached its max capacity and thus not able to continue protecting your AC system from making acid.
Anyway... the FSM says to....

__________________
1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

And do yourself another favor, since you have it discharged...

Go ahead and renew all the o-rings and flush the lines.
Change the oil in the compressor.

Pressure test, vacuum, and charge.

Yes it is a lot more work but well worth it.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

One tip I have seen is to make sure the receiver drier is the last thing to be installed, and dont remove the plugs from it until you are ready to go.