I know just enough about automotive A/C to be dangerous.

1994 Accord, currently has about 330K on it. Dad bought it new, has been meticulously maintained, and I'm having A/C issues with it.

2020 I replaced the original compressor with a new Denso unit. The original clutch bearing came apart, messed up the end of the compressor so that I couldn't put a new clutch on it, but the compressor itself was fine (so no catastrophic failure that would have gunked up the system)

Flushed the system, vacuumed it down, and charged. Worked great until late last fall.

Now it blows cold when I first get in the car, and after about 10-15 mins it gets warm. Checked pressure, and high side is normal, but low goes down and eventually shows a vacuum. If I turn the compressor/ hit A/C button on and off every few mins, it will blow cool air on my entire 30 min commute, but if I leave it on, the air gradually gets warm.

Everything I've seen says either obstruction, or the expansion valve.

Given that it works SOMETIMES, I think my strategy will be purge system, blow compressed air through lines, replace dryer, and possibly the expansion valve.

So, where is the dryer on a 94 Accord, and does anyone have a good write up on getting into the dash to replace the expansion valve?

The dryer on my Jeep and old 83 GMC pickup are very obvious. Not so much on this Accord. I found a youtube video showing the expansion valve replacement on a newer accord, but was hoping someone might have something for the 94-97 Accords.

 

I redid the whole a/c on my 95 accord. The expansion valve is inside the evaporator housing behind the glovebox.

Google cd7_cd9.pdf. This is a free pdf of the 94 shop manual and will help you a lot.

The a/c system requires several measurements to measure the system performance. Take a look in the shop manual for the a/c performance test. They also have some descriptions for abnormally low/high pressures that can help.

Does the a/c compressor clutch stop spinning when your low side pressure drops? Are both radiator fans running while the a/c compressor clutch is spinning with the pulley?

 

Thanks for the link to the FSM. Those are always a huge help.

Clutch spins constantly when the low side pressure drops. Both fans are operating as they should.

 

I noticed yesterday that after driving for a few mins with the A/C on, I could hear what is presumably the expansion valve cycling behind the glove box. I could hear a "thunk" and the compressor would come on, and then another "clunk" and it would cycle off. The longer I left he A/C running, the shorter the time that the compressor would kick in. Eventually it turned on for only a second before cutting back off, with the "clunk" being audible behind the glove box (had to turn radio off and fan on low to be able to hear it, so not terribly loud)

At this point I'm leaning towards evacuating the system, replacing the expansion valve, unhooking the lines and blowing them out, vacumming the system down again, and refilling with the proper amount of R134. Any other input?

 

I'd probably replace the receiver/dryer and all the o-rings in the system. The rec/dry is near the front of the car and is connected to the a/c condenser.

 

Looks like Rockauto sells a kit with the dryer, o rings, and expansion valve as a kit. Going to order that here shortly.

How far down to I need to pull it all apart? I know there's a line I will have to disconnect at the evaporator that runs to the dryer, so will obviously blow that out with compressed air. Will blow out the evap while I have it pulled to replace the expansion valve as well. Should I unhook and blow out the condensor as well? I'm leaning towards the expansion valve being the problem, but it appears that low side vacuum could also be caused by an obstruction in the system.

 

Replaced the expansion valve, the dryer, and related orings. Vacuumed it down and confirmed that it holds vacuum.

Charged up and it blew cold all the way to work this morning (30 min commute), so fingers crossed that it's fixed!

 

Since the system is working properly, you likely fixed the problem. Thanks for posting the results so other members can see this post in the future.

 

Well, after working fine for a bit, the dang evaporator started leaking. I would get a whiff of freon every once and awhile, and the A/C eventually stopped blowing cold again.

Pulled the evaporator and found green dye on the styrofoam liner confirming a leak in the evaporator core, so ordered a new one. Got the expansion valve moved to the new evaporator coil, added 1.5 oz of PAG, got it reinstalled yesterday, and vacuumed it down.

Held vacuum fine, and I went to put in 2 cans of R134A. Took the first can, but when the compressor kicked on, it almost stalled the engine. High side pressure was up there, and the high side port got hot to the touch. Compressor didn't kick on often, but when it did it really dragged down the engine. Neither fan was working either.

So first thing I have to address is the fans not kicking on. They were working fine when I pulled the evap core, so it's strange that they suddenly stopped working. The high pressure/ hard cycling on the compressor points to an obstruction, correct? I had the old evap core out for several days and I'm wondering if something got in the A/C lines going from evap core to the rest of the system. I can't think of any other way something got into the system unless it's a line coming apart.

Thoughts?

 

Doing some nosing around, I suspect I might have attached the capillary to the larger line instead of the discharge line. Guessing that's a big no-no. I'll pull the evaporator after work and verify that's what I did.