How to replace expansion valve...

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Jul 10, 2006 | 12:50 AM

ssanto

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Junior User

Joined: Jun 2006

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How to replace expansion valve...

Hi,

I am fixing the AC in my 1985 F-150. I have got the evaporator out and I am going to flush it and clean it. I would also like to change the expansion valve while I have everything apart.

How do I get the old valve out? Am I correct that the expansion valve looks like a grey peice of plastic that sits inside one of the evaporator's tubes? How do I change it? Do I just yank it out?

Also, when I opened the plastic housing to get the evaporator out, I noticed that it was sealed with what I can only describe as "black goo." It was very sticky and very gooey. What is this stuff? I might want to add some more to seal it when I put it back together? What can I use? RTV silacone?

Thanks,
Sal

Jul 10, 2006 | 08:18 AM

lsrx101

Fleet Mechanic

Joined: Feb 2006

Posts: 1,776

Likes: 5

From: Lorain County, Ohio

Quote:

Originally Posted by ssanto

Your truck doesn't use an expansion valve, it uses an orifice tube. Yes, it's the plastic thing in the evaporator inlet. It should pull out with a pair of needle nose pliers, just be careful. It's only held in by oring tension. If there's a lot of debris or grey looking paste in the screen, be sure to flush the condenser, lines, and evaporator. If you've had a catastrophic compressor failure replace the condenser, just flushing may come back to haunt you.
You shouldn't need to remove the evaporator unless it's leaking. Since you do have it out, look for oily dirt on the fins as this would indicate a leak. Clean it good (the outside)with a purple Power type cleaner.
The sealer goo is called mastick. You could use RTV but I would recommend Strip Caulk, available at most real parts stores or body shop supply stores.
Hope this helps.