I’ve got a 1994 Accord EX running R134a. Last year, the AC started blowing hot. So this year, I decided to fix the darn thing. It’s been a hot summer! I ran some dye through the system and discovered that the problem was in the evaporator core, a common problem with Accords.

So I bought an evaporator core, brand new, took the glove box apart, removed the evaporator casing and man, was the old evaporator trashed or what. It was bad. Lots of rust and the Styrofoam housing that encases the evaporator was melted into some sort of gooey looking syrup stuff.

Long story short…I replaced the evaporator, installed all new o-rings in the entire system, and put in a new receiver/drier. Added some oil for the new components as well.

Last night, I hooked up my gauges and vacuumed the system. Let it run for 30 minutes at 29 Hg. Closed the high and the low, then shut off the vacuum pump. It held vacuum for about 15 minutes, then started to slowly creep back down. When I woke up this morning, the vacuum reading was 20 Hg. My first thought was, “Great, still got a leak.”

Just for grins, I went ahead and ran the vacuum again this morning. This time for 45 minutes at 29 Hg. Closed all the gauges up, shut the vacuum off, and waited. That was two hours ago and the system is still holding a vacuum of 29Hg. It hasn’t moved a hair.

So my question is, what’s going on? The first vacuum I did last night wouldn’t hold pressure. But when I did it again this morning, it’s rock solid at 29Hg and hasn ‘t moved a bit. I’m thinking maybe the leak was in the gauges or the gauge fittings to the high/low side, or somewhere in the yellow vacuum hose. Anyone ever heard of that happening?

Anyway, should I trust that the leak is fixed and go ahead and charge the system up? Or should I let it sit for a while longer, like maybe through the afternoon, just to make sure it holds at 29Hg?

Any opinions from you AC pros out there would be very much appreciated.