Complete AC component replacement?


Active Member
I'm about to undergo some major surgery on my AC system. MOOSEMAN, any recommendations you have here are most welcome!
I have an 04 TB EXT and I plan on replacing the following components:
-Orifice tube
-all new o-rings/seals
-Lines to the rear AC
-MAYBE the AC lines under the hood as well.
-(And any other parts y'all recommend!)

I know for a fact the lines to the rear are corroded and need replaced. Bypassing the rear ac is not an option for me as I have kids and they need the air back there. So, now to my question:

Should I consider replacing the evaporator as well?? I really, REALLY don't want to! Tearing apart the entire dash to get to that is too much work, either on my own or paying someone to do it professionally. Would it be better to just have this component flushed? And if so, has anyone here ever flushed it out themselves? How do I go about doing that? Looking forward to everyone's answers!


Well-Known Member
Can buy a can of "ac flush" at the parts store to flush it. Blow it out vigorously with an air compressor. Also I believe you're supposed to run a longer vacuum cycle when pumping it down to fill with freon. Might be worth mentioning to the shop you take it to if you're not refilling it yourself.


Be ready for the suck when you do the rear lines. Are you using OEM or aftermarket rubber lines? Heard that the rubber ones are not that flexible and I can't imagine the OEM hard lines being any easier to use. I had trouble with just the tranny lines. I bypassed mine and no complaints from the kids except the one time an adult sat in the very back when I was using inefficient e-fans. If you do bypass it, replace the o-tube from the gold to white one and don't use recirc. Once I went back to the stock clutch fan, the A/C was ice cold.

Unless you confirm that the evap is leaking, don't replace it. I replaced mine once I confirmed that it was leaking with a leak detector. It's a full one day job. Same for the underhood lines. Haven't heard of anyone having to replace those.

Make sure your fan clutch is working properly.
How to test the electro-viscous fan clutch


I just ran across this the other day - flexible AC hose assembly for rear AC in TrailBlazer EXT's and Envoy XLs:

If you already are aware of these, my apologies.

Since it's from Dorman, I know that it can hit or miss.


Matt, good to know.

As an aside, their windshield wiper transmission for 1999 Buick Centurys is junk. Dorman uses a too shallow cup to connect to the wiper motor's crank arm and it keeps popping off rendering the wipers useless.

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