ultraclyde Dork
May 18, 2013 6:05 p.m.

Okay, so I'm trying to get the ac in my 97 exploder ( build thread ) working again. The short background is: two summers ago I had a backyard ac guy install new (not rebuilt) compressor, manifold lines, receiver/ drier and (I think) evaporator. The first time I got it back I immediately had to loan it to a family member, and it quit cooling in about a week. I took it back and that was the point he installed the hose set. I got it back again and it cooled for 2 days before quitting. I had to go out of country and never got it back to him. Now I'm trying to get it fixed myself. I've never worked on AC, but it can't be that hard, and I'm tired of paying someone.

When I started you could switch on the AC and the compressor wouldn't run. If you jumpered the low pressure cut-off, the compressor came right on but it never cooled. That pointed to a leak somewhere that had lost all the freon. I bought a freon fill with UV dye and seal conditioner in it, along with a UV light. I put the whole can in and followed it with a half can of straight freon I still had laying around.

After leaving the compressor running on max AC with the switch jumpered for 15-20 min, the interior vents were blowing cool, but not as cold as it should. I shut down the engine and scoured the engine bay for signs of leaks. I found absolutely nothing. Checked all the lines, compressor, condensor - everything but the evaporator which you can't really see. Everything's dye free. I drove it a couple days, running the air but never really cooling like it should, and it's still leak free.

I think I may not have enough freon in it for it to really cool like it should. The compressor cycles pretty quickly on max cool, staying on about 5 sec, then off about 5, back and forth. The pressure gauge I have keeps the needle in the blue range as it cycles. (video link here, not sure how it will work.) If I jumper the low cut switch and force the compressor to run, the vents will eventually blow colder than letting it cycle, but still not as cold as it should.

Do you think it needs more freon?

As for the distinct lack of dye leakage.....I don't have a clue. You can't really see the evaporator, but I'm pretty sure it's new. Also, if it was leaking, I would think that some of the UV dye would show up in the condensed water that drips under the car, wouldn't it? Also, you can't see the back side of the condenser because the radiator is against it. Is it likely that you'd have a leak on the backside that couldn't bee seen in some way from the front?

After several days, the pressure seems about the same, so I guess IF it's still leaking, it must be small.

Guidance, oh wise ones, guidance...

JohnyHachi6 HalfDork
May 18, 2013 6:21 p.m.

If the system has/had a leak and was totally empty when you started, it will have been full of air and at that point you really need to pull a good vacuum on the system to evacuate the air, then charge it with refrigerant. Having a significant amount of air will keep the system from working properly.

ultraclyde Dork
May 18, 2013 6:25 p.m.

hmmm....that's an interesting point. Could it keep a leak from showing up somewhere?

Knurled UltraDork
May 18, 2013 6:46 p.m.
ultraclyde wrote: I bought a freon fill with UV dye and seal conditioner in it

Replace everything again.

That stuff reacts with moisture in small orifices to harden. The problem is, if there's any moisture in the system, then it hardens in all of the many small orifices in the system.

The fun part is, now nobody will touch it because that stuff also destroys A/C equipment. Nice $20,000 oopsie.

Yes, I think it's criminal that they sell that crap.

ultraclyde Dork
May 18, 2013 7:33 p.m.

So..well berkeley.

EDIT: after a some quick research it appears there are two types of stop leak - the one you're describing and one that is just a solvent that makes rubber swell. I've got to check the can and see, but I think (hope) I got the benign one.

Ranger50 PowerDork
May 18, 2013 8:53 p.m.

Backyard AC guy? Probably never vacuumed the system down, either long enough or even did do it, to boil out the moisture. At minimum, a new drier, seal inspection, and finding someone else to charge it properly.

If you put in stop leak R134a, replace everything, CHA-CHING. Those cans should be outlawed or only for sale to repair facilities.

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