2000 CTD Having a A/C problem, last two years I've had to add 1 lb of 134 to get it to blow cold (slow leak) well last month I added my can, then bled down in two weeks, then added another can with dye on Monday and Friday it was blowing warm again and compressor cycling every minute again found my system had a leak at the high side servicing valve. Replaced valve, pulled a 26in vacuum on system for 25 minutes to see if that was the only leak- held fine no change, then put 100psi of shop air in to test for leaks- no change. Pulled a vacuum again for 30 to get ready for a full charge, system blowing cold for the drive home. Next afternoon ready to home and it's blowing warm air, and compressor cycling every minute due to low charge. Heater temperature selector working normally. We used a blacklight in dark garage to check for dye leakage, none that we could see at compressor and only just a bit at the low side shrader valve from the previous charging. checked low pressure hose at heat shield no evidence of leak there, so now what? My mechanic said next step is to replace compressor etc
Have yall had any compressors leaking and not giving any indication of a leak?

 

Sounds like a classic Evaporator taking a dump case......... Look for dye in the water drip hole.....though I never did see any when Brownie was leaking.

Will it hold the vacuum?

 

It held the vacuum for the twenty minutes we tested it, i'm thinking I'll throw a can of sealer 134 in it to see if that helps.

How much is it a PITA to replace the evaporator?

 

I just did it (and heater core) this past Sunday. Not too bad really, dash comes out fairly easy. Then the whole heater box comes out. I had a slow leak for the last year or so, then all of a sudden it leaked out over 2 days. The stop leak did help for a while, but once I saw the evap. core I can't beleive it worked. It was caked with pine needles/leaves/junk almost half way up the core, lots of corrosion. Much more air comes out the vents now.

 

I just did the evap last month. The UV oil won't help you find an evap leak, you need a sniffer. I charged my system, let it sit for a couple of hrs then put the sniffer tube in the vent and turned on the key..it went nuts. I guess I could have put the tube in the condensate drain but inside the truck was easier.
Evap $69 from Advance Auto and another $80 for the hose section out of the compressor. $90 for a 30lb canister of 134. I got the extra freon to be able to flush the system and it worked out cheaper than buying a dozen little cans. I replaced the hose because I noticed that my oil bypass hose had worn the aluminum tube part pretty thin and didn't want to do the whole thing a second time. I also bought a cheap set of gauges from HF for $50, my old set was for 12 and 22 and I couldn't get hose adapters as cheap as a new manifold set.
The evap was a bit of a PIA. You have to take the entire airbox out of the dash. Once you get that out there was nothing to it. I replaced the foam and weatherstripping on all the blend doors since I had them lying on the driveway.
All told for under $300 I had ice cold air, a new gauge set and about 20lbs of 134 left over. Cheapest I could find a shop to do it was over $900.

 

Leaning towards evap replacement too, anyone come up with a way to pressure check only the evap? I was thinking of hitting the wrecking yards for a couple of scrapped lines to get the ends and the service port, weld up the ends and voila .My dash is toast I'll have to invest in a bunch of JB weld to patch it back together.

 

Jumped off the deep end and took the dash apart to remove the evaporator, finally found the last nut for the heater box under the computer.
Mine was toasted. Going back together tomorrow with a new heater core too. Dang that front seat is heavy. Anyway here's afew pics of my journey. Dash patched with clear epoxy to make it easier to reinstall.

Would like to replace the firewall gaskets too, y'all get those at the dealer or make your own?

 

All charged up and blowing ice out of the vents!