Removed evaporator.... can't budge allen screws from valve

[BullElk]

I'm trying to loosen the allen screws but only end up rounding the edges on wrench. I MUST get these off to use the hose connectors. Or...know a better way to loosen Allen screws??

Thanks

 

[Jeepster09]

Is the expansion valve junk that you are trying to remove it from? Only ask because the bolts may have loctite on them [or they are just siezed] and may require you to apply heat to bolts. The heat could damage valve. You are using metric allen wrench right?

 

[flintknapper]

They're METRIC and pretty tough if original, you shouldn't be rounding them out.

Correct metric allen key in a socket on a 3/8" impact will run them out.

 

[nissanh]

Use a good branded locking plier to break loose the bolt.

 

[flintknapper]

Is the expansion valve junk that you are trying to remove it from? Only ask because the bolts may have loctite on them [or they are just siezed] and may require you to apply heat to bolts. The heat could damage valve. You are using metric allen wrench right?

It's pretty normal for these to be difficult to remove. They are a dissimilar material (Carbon Steel contacting Aluminum) and over time they react to one another forming a sort of 'corrosion' on the threads. Very important to have a tight fitting Allen Key.

 

[BullElk]

Thanks a lot for the responses. I am not positive about being metric or not. It felt like it was snug. Just thought maybe it was a cheap wrench. I'll get a good one and perhaps some liquid wrench.

 

[BullElk]

Finally got the screws out safely but would like to replace if possible. They are really corroded after 18 years. Any chance Lowes would sell these Allen screws?? Would it be stupid to NOT replace the expansion valve as well?

Thanks guys

 

[Jeepster09]

I would think you would do better at a hardware such as ACE, I doubt Lowes would have metric allen bolts. Maybe NAPA? If the threads are still good in valve I would not replace it [if it works]. Try cleaning bolts on wire wheel, if clean up ok, use never seize and re-use them.
Try running tap carefully into expansion valve threads to clean up.

 

[BullElk]

Actually, there are no threads in the expansion valve. Only in the evaporator that will now be a new one. I found the correct size 5 mm bolts but in a stainless hex head. I don't see why the head type would matter. I just don't know if I should use original valve or not. Don't think it's bad. Wouldn't mind taking back the $33 valve I bought, however.

The diagnosis was the freon leak detector found leak at the drain valve so I'm thinking the evaporator is the problem.

 

[Jeepster09]

Are new bolts the same hardness? Some stainless are pretty soft material. I would actually reuse old bolts if they clean up. MOST allen bolts are equivilant to Grade 8 or better. If old expansion valve worked and has no issues I would re use it.

 

[flintknapper]

Yes, use the NEW TXvalve. Keep the old one for a spare if you like. No way I'd do an A/C job that involved pulling the Evaporator without replacing the TXvalve (if older than a couple a years) and the drier.