cqljohn

Got a 97 Civic and having issues out of the AC. Bought the car used, AC worked but not very cold (80 with my guage), added 12oz R134a with cheap hose. Got cooler, but still not cold (about 65 on my guage), added a little more R134a and went over charge, which kicked the compressor out. OK, I fiuge the system didn't have enough vaccum from the beginning. Emptied system, pulled vaccum to 28-29, then added the correct amount of R134a. Not very cold at all (about 65-70 with my guage). Gauge readings were about 15psi on low side, 250 on high side. I added a little more R134a thinking it would raise the low side up, wrong, the high side increased, but the low side is still about the same (around 15psi). Now I'm thinking the expansion valve is bad from my research, creating a blockage. I am now overcharged again, but at least i know there is something wrong in the system. What do you guys think?

Also, the second time I added the R134, I weighed the can on my digital scale, it weighed 15.1 oz for a 12oz can. Empty the can weighed 3.3oz, so am I correct in figuring I added 11.8 oz's to the system. I weighed everything until I had the system charged to the correct amount of 22.9 oz.

This is my first AC repair, but I am very good working on auto's and usually good at diagnosing things before I work on them, and try to avoid being a parts replacer, which may be a hit or mis game. I know if I replace the expanion valve the drier will need replacing also, just wondering if I've missed something.

Former User

To make a diagnosis, you need to take pressure readings under these conditions:



Is this what you did? We also must know the outside temp and relative humidity when test was done.

For example, here's a chart showing what the pressures should be at ~85F and high humidity:

cqljohn

Ron,

I have a therometer is the vent.
Car's been in shade all day.
Doors open, no one inside, set to max cool, recirculate is on, fan on high.
RPM is 1,500.

Results after 10 minutes.

64 degree's at the middle vent.
Low side 20psi.
High side about 320, hand is fluctuating rapidly between 300 and 350, with 320 being the centerline.

Low side line is cool to the touch, not cold. High side is HOT!

Outside temp is 93, with humidity about 55%.

All this is after I added more R134a, I figure I'm probably over 6 oz or so.

I'll post a video after youtube is done with it.

Edited misspelling.

cqljohn

http://www.youtube.com/watch?v=KUbK-sQ3xFI

This was after it ran about 6-7 minutes, after it ran 10 min I got the results I posted above.

Former User

Despite the refrigerant overcharge, both the low and high sides are reading too low. Your readings are 20/320 but the chart below shows that they should be approximately 45/390.



The service manual says that these reading suggest this:



There seems to be some type of restriction in your system, which I think is also consistent with the abnormal fluttering of the high side needle.

cqljohn

do you think my way of caculating the amount of R134 was correct? I'm sure I have over 2 cans, 24 oz in the system, from 3 different cans, started with a 1/2 can. I weighed everything on a digital scale and subtracted the can and the can adapter. I can't seem to get the low side up. Would you add more refig before tearing it back down?

exb18c1

On the picture above the condenser looks very damaged.It definately doesn't do the job!Try to pour cold water on it while the gauges are on and see if you will get different result.When you will change the condenser you better change the dryer because it get saturated with moisture.

Former User

Adding refrigerant by weight the way you did is correct. I would not add any more refrigerant.

Let me share some personal experience with both A/C systems in my 97 and 00 Civics. The high side pressure is to spec. However, my low side pressure is substantially lower than the chart suggests it should be, as is my discharge pressure (good I guess?). Nonetheless, my low and high side pressures are steady on the gauge and show no flutter, as yours do. It's the flutter that concerns me the most. I recommend that you read this thread and then PM the thread's OP.

cqljohn

Hey Ron, Do you think it's safe to assume the compressor is good and NOT an issue? I mean the this is pumping about 400 psi. I would assume a bad compressor would be weak? I'm thinking I will replace the condensor, and expantion valve, drier also. I also will probably clean the entire system of oil, and reapply oil. I bought this car with this problem, and the thought occured to me that it may have too much oil, which in turn is overpowering the refrig and not allowing the refrig to get to get to the correct temperture. With all the cans of magic they now sell in cans that can easily be appied to the system, who knows for sure what really is in the system?

slowcivic2k

Your low side pressure is too low, low pressure indicate low transfer of heat in the car. If you raise the RPM above 1500 rpm, does the needle drop below 15psi? It sounds like the expansion valve is defective. But before we go replacing that thing, try these things:

Ensure the condenser fan operates whenever the compressor is on, if not, fix it.

Ensure the fins on the condenser are not all peened over, blocking airflow, will impair system performance.

Generally speaking, when an expansion valve fails to open, the high side will be normal, perhaps slightly low, and the low side very low, or in vacuum. Once all the refrigerant moves to the high side, it is cooled by the condenser, stabilizing the pressure, but stays that way because the valve isn't opening. Valves that are on their way out may cool intermittently, which sounds like your case.

I would dismiss the high side fluctuation at this point, because if all the refrigerant is on the high side, when the compressor opens to discharge refrigerant, the pressure forces it back in, causing the flutter.

Former User

^This guy is an A/C expert, so do listen to him.

cqljohn

Condenser fan is working.

Fins on the condensor ARE peened over. Replacing it tomorrow or Saturday. Looks like the factory 1997 condensor. Already have the new parts.

Expantion Valve, Evaporator and Drier will also be replaced while it's apart. While I got it apart I'm going to fully clean the system of it's current oil, and replace with the correct amount of new PAG 46 oil. I have no idea what's in the system currently, as I bought it recently.

The system is currently working great one minute and not working the next minute. I know the system is getting VERY high psi on the high side, and I assume cutting the compressor off. It can be 100 outside, and as long as the car is in motion it will cool, stop and it starts getting hot, and then the compresssor kicks out, again I'm sure it's due to the high pressure on the high pressure side getting high enough to kick it out.

I'm generally not a parts replacer until I find the problem, but it looks like this thing has a lot of wear and tear (230,000 mile) and everything just needs replaced due to age. I'm sure the evaporator is "OK", but while I'm in there, might as well replace to make sure it is working correctly.

I'm almost certain the expaintion valve is bad (based on research), I know the condensor needs to be replaced (due to the visual), the drier needs replace (once the system is opened) and the cleaning and oil changed (because I don't know what the hisorty is or what the hell is in there).