hupp

I have almost completed my HVAC project -- new compressor, hoses, expansion valve, reciever/dryer and system flush. For the most part the system is completed, but I have not installed my new dryer yet. Is it best to leave the new reciever/dryer sealed or can I install it even though the system will not be serviced and filled for a week?

joejoe

While I have changed and immediately evacuated and filled I see no problem with installing and empty for a week.

Prionace Glauca

Here is a tip from one of the A/C forums.

[I]Auto A/C Tip 10
When either installing a new a/c system or doing a service job always make the drier the last component replaced before evacuation and recharge. The desiccant in the drier absorbs moisture and will decrease performance and create a problem to the system at a later date. Moisture and refrigerant when combined creates an acid and will damage the internal parts of the a/c system.

davek9

I was thinking about replacing the dryer and expansion valve too before taking it into the shop to have it evacuated and filled to save some labor $’s.
I was hesitant about leaving the new dryer in an uncharged system, thanks for posting; this confirms my fears about absorbing unnecessary moisture.
I guess now I’ll just pay for them to do it on as part of the conversion process.

Scott when you replaced your expansion valve was it exactly the same size?
The replacement part I received is thinner than the part in my 85’ and I don’t know if I will be able to connect the four fitting as they don’t look movable (one side will need to be ~ ½ ” longer).

SharkSkin

If you're going straight to the AC shop on Monday after installing a new dryer on Sunday, you'll be fine -- just ask them to keep vac on the system for 1-1.5 hours instead of the usual minimum of 30 minutes. The dessicant will not hold the moisture under vacuum for very long.

hupp

Thanks for the replies -- I was unsure about leaving the dryer installed on an uncharged system for a week. I will be leaving the dryer off and sealed. I'll just ask the mechanic to install the dryer (and compressor belt) before charging.

davek,

The expansion valve was an exact replacement and was a pain to remove an install. The worst part was that one of the evaporator fittings was motherf@#$ing tight and really tested my tempor and nerves. The last thing I wanted to do was round an evaporator fitting. You may have to remove a bracket (located on the firewall behind the air box on my '79) in order to gain some line flexibility, but 1/2 inch seems excessive. Take a look at Sharkskins page "AC chillin" link. You will find a good write-up on the valve R&R. He has a link in his signature.

BTW Sharkskin -- your page is now saved in my favorite links and I refered to it multiple times during this project. I also installed the griffiths kit and it was nice to refer to the info from someone who's been there!

SharkSkin

Thanks Scott, glad you find it useful! I'm way behind on updates though -- need to lock myself away for a weekend and get on it.

Davek, don't you have the later style expansion valve, with a single allen screw holding a retainer plate on each side? Where did you buy the expansion valve?

davek9

SharkSkin great write-ups on you web site!
And no my expansion valve looks EXACTLY like yours; the part number for the new one I received from 928specialest is marked:
TCDF 2D R 134a No: 3 22 308 (made in France).
The new dryer is a BEHR 50992A (a label on the unit says it replaces: 928.573.141.03)

Thank you, Dave K9