Jon Petersen

95 Civic EX. AC has been completely empty since May when I found huge leaks in the condenser. Just now replaced it. Looking up the capacities, I found that the AC system holds 19 oz of refrigerant and 5 oz of oil. It's recommended to add 2/3 oz of oil when a condenser is replaced, but since it's been dry for so long, should I add the full 5 oz? I'm planning on pulling a vacuum before I charge it so I can evacuate any moisture, but will oil remain in the system through a vacuum pull? Thanks friends.

mk378

Replace the receiver-drier. It's an expendable part like an oil filter.

Ideally you would flush the old oil out of all parts and use 5 oz of new oil. But if you don't have the equipment and initiative to flush properly, don't try a half-*** flush. Instead add 2 oz or less of new oil total to replace that trapped in the old condenser and drier. Too much oil is bad.

Pulling a vacuum does not remove oil.

Jon Petersen

Thanks man. Question: will not replacing the receiver/drier be bad? It's beneath the power steering reservoir and the windshield fluid reservoir and looks like a cussing pain to get out. What do you suggest?

holmesnmanny

oil won't leave the system unless it's leaking out with refrigerant, if it says to add 2/3 just add 2/3, but also add about a 1/3 ounce for the drier as well, so add about an ounce total

if you absolutely don't want to replace the drier, atleast pull a vacuum for an hour to fully evacuate the system

Jon Petersen

Thanks for the help. I got out the receiver drier and pulled a vacuum for an hour. I got a question. While recharging the AC, I was noticing that the compressor had some trouble kicking on. It would come on, then come off without a pattern it seemed. When it did kick on, the high end side was at 100 psi (where it should be, I believe) and the low end side was at 30 psi (I think it is supposed to be at 10 psi). The thing is, the first time the compressor would not kick on, I checked the manifold gauges to make sure the low side was open, and I accidentally opened the high end pressure valve. I quickly closed it, but I think some refrigerant might have gone in to the high end side, which freaking sucks. Could I have caused serious damage to my AC system, or do you think it should be fine? The air felt cold, but then again, it was about 40 F outside (strange time to replace AC components, but hey, I am ahead of schedule). What is your take?

mk378

Charge the refrigerant by weight and call it done for now. The compressor will cycle off when the evaporator temperature goes below 35 degrees. Since it is only 40 outside to begin with, it's not going to run much.

Putting refrigerant into the high side doesn't hurt anything. It's a good practice to charge the first can into the vacuum with the engine off by opening both valves. Of course you should never open the high side valve when charging with the compressor running because (a) it won't work, and (b) refrigerant could get forced back into the can and make the can explode. Most can tappers have a check valve to try to prevent (b).

Jon Petersen

Thanks man, you've been a ton of help. I'll let you know how the AC works when it's hotter. Thanks again.

Jon Petersen

Tried out the AC today, it was ice cold! There was a minute where the AC went hot, but I held the engine at ~1500rpm for ~10s, and it went back to ice cold. Thanks for the help, man.

mk378

If you experience further "intermittently doesn't cool," when it stops cooling pull over and leave the engine running and the A/C on. Open the hood and check:

Is the compressor engaged?
Is the condenser fan running?
Is the low side line cold?

Jon Petersen

Okay, so I've encountered a lot of the intermittently doesn't cool, and today was the first time I've been able to pull over and check it out. The culprit was that the condenser fan did not turn on, so the low side line was not cold. I find this a little weird, because sometimes when it intermittently doesn't cool, it's 40 or so outside, but the sun is cooking me so I want it on, but other times, it's 60, or 70, like, well over the temperature most would at least think about stayings up the AC. What's going on?

mk378

Was the compressor engaged?

Compressor on but no fan would be a problem with the fan or its relay (the fuse is the same one as the compressor, so it must be good).

If neither the fan or the compressor is on, the controls are not calling for cooling.

Jon Petersen

There was a lot of clicking both times I checked, so I assumed it was on. The first time I pulled over, the condenser fan stayed off. The second time, the condenser fan alternated between on and off, and when it turned on, the low life was cold, as was the AC.

Jon Petersen

Maybe it's worth mentioning that when my AC works, after I turn off the car, there's a humming "power-down" noise, kinda like you'd hear in an old computer or TV. When my AC does not work when I turn it off, this noise doesn't happen. Could it be that I didn't charge it correctly? If so, would evacuating it and re-charging it fix the problem?

mk378

It is normal to hear the refrigerant flowing after shutdown as the pressure equalizes. Since it can get cold, you know there is enough refrigerant.

You really need to watch exactly what the compressor is doing when it is not working. Clicking on and off rapidly is from overpressure because the fan doesn't work. In that case you should get cooling when the car is moving. If it stays off along with the fan, it's an electrical problem.

Jon Petersen

Rapidly, like on and off every ~10 seconds, or faster than that? From what I've observed (I can't see the compressor from the side, only from the top because of where it's located) the compressor stays on while the fan alternates on and off. I'll inspect more and let you know. Thanks for the help, man.

Jon Petersen

Okay. So, upon further inspection, I've found that the compressor clicks off at the same time as the condenser fan, which causes the cooling to stop. It's an electrical problem then? How would I go about diagnosing and fixing that?

mk378

The controls inside the car send a ground to the pressure switch to make the A/C engage. The three parts involved are the interior fan switch, A/C button, and evaporator thermostat. You can bypass any or all of them by jumping or forcing a ground. A schematic should be consulted to get the wire colors.

Also check that the heater water valve on the firewall is closing completely when you have the dash temperature lever at full cold. You may just have the heater and A/C fighting each other. The evaporator thermostat is supposed to cycle the compressor off when the evaporator temperature reaches about 36 degrees. That can be working but the cold air is being reheated on the way to the vents if the heater core does not shut down.

Jon Petersen

I've never done any electrical work. Do I test every part's continuity with a multimeter? How do i force a ground? Wire colors for what?
Do you think it could be the temperature sensor I have to replace? I'm not sure where the heater water valve is, but I could look I'm my manual. I'm not sure that's it because it turns ice cold when it works. But it could be, should I test the ac pressure too?

mk378

As the compressor has stopped running you know that is why it is not cooling, it is not necessary to measure pressure.

The heater valve is where the heater hoses go through the firewall, directly behind the engine almost exactly in the left-to-right center of the car.

To bypass the evaporator thermostat, remove the glove compartment and find it on top of the glove box. It is a small box about 1 inch x 2 inches, with a 3 wire plug (and two permanently attached grey wires on the other end). The wires in the plug should be black/yellow, blue/red, and yellow/white. Unplug the plug and use a paper clip to jump the blue/red to the yellow/white. Do not connect anything to the black/yellow, that is the power source and shorting it out will blow the fuse. Test drive with it bypassed. It may stop cooling due to freeze-up, you would need to release the A/C button and let it thaw.

Jon Petersen

Thanks man. It looks to me like the heater valve is working fine. I haven't tested the evaporator thermostat yet. I thought of something: could it be possible I over-charged the ac system? I could get it evacuated and recharge it with refrigerant at Walmart to see if that does anything. What are typical symptoms of an overcharged AC system?

deschlong

iTrader: (8)

I saw your post a while back about intermittent AC problems and thought I could help by scanning the Air Conditioning section from the 1995 Civic Service Manual that I have. Problem was that the manual was buried in storage and my printer / scanner was still in its box. Well I got my printer / scanner out this week for a job, and figured I should test out the scanner too.

Attached is the AC section from the 1995 manual. The 1992 Civic service manual is available online but is confusing for AC troubleshooting because: A. It's for R12, and; B. They changed the AC wiring in 1993 (R12), then again in 1994 (R134a). I had an intermittent problem with my compressor, which finally turned permanent. A lot of "WTFs" were uttered as I tried to use the 1992 manual on my 1993, not knowing the wiring had been changed. Wound up using the 1996 Service Manual since it was wired more similarly. You'll need to familiarize yourself with using a multimeter for diagnosis. Good luck!