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Accord charging problems

webbch on Thu August 12, 2010 2:34 AM User is offlineView users profile

Year: 1992
Make: Honda
Model: Accord
Engine Size: 2.2L
Refrigerant Type: R12
Ambient Temp: 68
Pressure Low: 20
Pressure High: 150
Country of Origin: United States

A year ago, I evacuated and charged up my 92 accord to the factory spec of 30 oz. of R12. A couple days ago, it wasn't cooling on my way home from work. The next morning, I checked the pressures before going to work. They were 20/150 at 68 deg ambient. I interpreted this to mean I had a low charge. So tonight, I again evacuated the system, withdrawing 22 oz, indicating that 8 oz leaked out over the period of a year. After pulling a vacuum for 30 minutes, I was going to charge it back up to buy some time until I could find and fix the leak.

It was late, and with the bugs eating away at me, I took a shortcut and didn't wait to see if it was holding that vacuum. I went to charge the system (using virgin R12), and was surprised at how easily the refrigerant went in (charged through the low side port of course). Normally I have to rev the engine to get the last several ounces in. In this case, it just kept sucking it in until it had gotten the full charge of 30 oz running at idle. After I closed the low side port, it continued to pull a vacuum on my low side gauge, and the high side was at about 100 psi. Is this indicative of a now-massive leak such that anything that went in came out immediately?

I'm confused as to how the low side could be so low and not only have the compressor still running, but also not be cool in the least. Any ideas? I rather wonder if pulling the vacuum caused the slow leak to turn into a fast one. I'm planning to evacuate again tomorrow, put in a little 134A and pressurize with nitrogen and go to town with the electronic leak detector. Thanks.

Chad

mk378 on Thu August 12, 2010 5:11 AM User is offline

Could be leaking out rapidly like you said. If properly charged, the low side dropping into vacuum means there's a blockage in the system. For example TXV clogged up or stuck closed.

webbch on Thu August 12, 2010 9:44 AM User is offlineView users profile

Thanks! I hadn't thought of that. I let it sit overnight and went out this morning and it was working. At 74 deg F ambient, I had 39 deg vent temperatures, and 25/175 low/high side pressures.

In light of this, I'm wondering if I possibly have a "sticky" TXV. I'll drive it over the next couple of days and see if the problem re-ocurrs. I'm sure it will.

webbch on Sat August 14, 2010 10:29 PM User is offlineView users profile

Sorry for the double post....

I was able to again duplicate the problem today. Ambient temperature was 91 when I started the car with the gauges hooked up. For about the first minute things seemed to be looking good. low/high side was 25/250, and vents were at 55. Then the problem appeared, and the pressures went to 12/210, and vent temperatures went up to 72.

As mk378 pointed out, there's a blockage somewhere, possibly the TXV. Can I presume the blockage is NOT in the condenser because the high side pressure's aren't sky-high? I'd rather not pull the condenser and fiddle with those connections without good cause.

I'm leaning toward pulling the evaporator and replacing the TXV (flushing the evap while it's out). It doesn't look like pulling the evap on this model is that big of a job. I'm not into replacing parts for the heck of it, but would NOT replacing the evap given it's age just be plain stupid? Thanks again for your help. You guys have given me lots of valuable advice over the last few years.

TRB on Sun August 15, 2010 1:50 AM User is offlineView users profile

12/210 does not seem to be a restriction to me. More like a core freezing up or maybe even a bad valve. Do you lose air volume when the temp goes up?

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webbch on Sun August 15, 2010 9:59 AM User is offlineView users profile

I haven't noticed a decrease in air volume at higher temperature. It's pretty much always had insufficient air volume at any temperature. Even with good vent temps the air volume is barely enough to cool me on those 100+ degree days, much less any passengers in the back seat. I've heard these accord systems are pretty marginal to begin with, so I attributed this minimal airflow problem to a design flaw more than a system malfunction.

Just as a check though, after getting the 12/210 pressures, I shut off the car and waited for my low side to climb up to 40 PSI (about 2-3 minutes), then started it again. It _IMMEDIATELY_ went back to the 12/210 pressures. So far, it sounds like everything's pointing to a sticky TXV.


Gary Harrison on Sun August 15, 2010 10:06 AM User is offline

I would be surprised if you don't have at least some leakage at the expansion valve and thermal bulb orings. I've had 2 Accords (90 and 94) and both eventually leaked at the expansion valve orings. Some type of dissimilar metals corrosion occurs at the connections between expansion valve (brass) and aluminum evaporator fittings. It forms a white powder which distorts the orings and they eventually leak.

I also had one expansion valve failure; failed open.

Getting the evaporator out is not too bad a job. Get a manual and follow the instructions. If you've never replaced blower, you might consider replacing the blower at same time as it's easier to access w/ evaporator out, but can be replaced w/ evaporator in place.

good luck

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See you down the ROW.

webbch on Sun August 15, 2010 10:51 PM User is offlineView users profile

If the evaporator ices up, would it produce the 12/210 at 91 deg ambient symptoms? Would it make sense that it would have more of a tendency to occur on hotter days? There's was a lot of gunk on the evaporator fins that appeared to be a major restriction to airflow.

I'm thinking that on cooler days, there is sufficient airflow to keep the evaporator from icing up at the lower refrigerant flow levels. However, there is insuficient airflow to keep it from icing up when it attempts to flow more refrigerant on a hotter day. Of course, this assumes the expansion valve is functioning properly.

I'll replace the expansion valve as a precautionary measure, but I'm beginning to believe that all the junk on the core may be the main source of my symptoms. Given how easy it was to pull the evaporator, I may just flush it for now.

BTW, are there mufflers on the suction/discharge lines on this vehicle? I don't have a picture, but they're metal lines that increase in diameter for about 12 inches or so. However, these sections are also ones that are closest to the exhaust pipes, so I wonder if they're simply heat shields. Thanks.

Chad

Edited: Sun August 15, 2010 at 10:56 PM by webbch

mk378 on Mon August 16, 2010 11:38 PM User is offline

Frozen evaporator will lead to the suction line under the hood also icing, or at least getting very cold. If it is not, there is a different problem.

webbch on Mon August 30, 2010 10:46 PM User is offlineView users profile

Update:

Since I'd never done it before, I decided to flush the entire system and start over (except the compressor). I disconnected and flushed all the lines (using HECAT Pulsator), the condenser, and evaporator. I then replaced the expansion valve using prestite tape on the bulb and re-assembled everything with new orings along with a new drier. I added 2 oz of mineral oil through the low side port, pulled a vacuum, added 1 oz of R134a, pressurized with nitrogen on 2 occasions and tested for leaks, and detected a very slow evaporator leak. So I ordered a new evaporator, leaving the system pressurized with nitrogen while waiting for the evap to arrive.

I proceeded to replace the evaporator, and noticed that there was oil in the old one, even though I had flushed it and never started the system. I presumed this was from my pressure tests, and so I added another 1.5 oz of mineral oil (this time directly into the evaporator before installing.

I pulled a vacuum, then added 134 and nitrogen another several times because I kept detecting a vacuum leak. Ultimately, I ended up tracing this leak to my micron gauge and not the system. So I finally removed the micron gauge, pulled a deep vacuum for 45 minutes, waited an hour and detected absolutely no movement on the vacuum on the manifold gauge, and recharged with 30 oz of R12. I then started the car and noted that at an ambient of 84 F, I was getting 36/310 at 1500 RPM and 52 deg vent temps, so the high side was WAY high.

Tonight, it was 77 ambient, 52 deg vent, and I ran it for quite a while, getting 28-30 low side, and 250 high side at 1500 RPM, (200 at idle of about 600 RPM),which is still higher than expected. Thinking it may be a condenser issue somehow, I misted the condenser with water, and the high side slowly dropped to 225.

Any ideas on what could cause my high side pressure? The system was opened up a few times after the new drier was installed, but no more than a couple hours total, although it has been humid out lately. Also, I may have added 1 additional oz of oil into the low size port by mistake. Any ideas would be appreciated. Thanks.

Chad


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