Automotive Air Conditioning Information Forum (Archives)
My Gauge readings and diagnosis
mrjoeyman on 
Sun August 21, 2011 8:40 PM 
Year: 1997
Make: Honda
Model: Accord
Engine Size: 2.2 Vtec
Refrigerant Type: R134a
Ambient Temp: 95F
Pressure Low: 40
Pressure High: 400
Country of Origin: United States
Seeing that my gauge readings are as stated and that I only get semi cold air when the car speed is from 45 to 55 mpg, and my condensor fan and my radiator fan appear to be working properly,I feel like my condensor might be plugged up to a point where it is not allowing the heat transfer to the outside atmosphere. This could cause my over pressure on the high side, or at least I have read. The compressor is undoubtably working, ie the high pressure and the semi cold air at driving speeds. Is there something that I am overlooking here? Could it be an expansion valve not functioning correctly? Also let me add that the compressor seems to cycle in short cycles during this time. I would say at driving speeds I can feel it come on for about 20 seconds and then shut off for about 40 seconds, if this information helps. Please advise on whatever other checks I can do to narrow my diagnosis options further. Thanks very much for the consideration. I have tried to do extensive reading to get to this point so I feel like I have done my homework to some degree. Nice to meet you all 
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~Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you're a mile away and you have their shoes.~
TRB on Sun August 21, 2011 8:45 PM
How much refrigerant is in the system? Why do you think the condenser is plugged?
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Contact: ACKits.com
mk378 on 
Sun August 21, 2011 9:00 PM
It could be overcharged with refrigerant and/or oil. Has any been added? The scroll compressor systems are real sensitive to too much oil.
GM Tech on Sun August 21, 2011 9:02 PM
sounds grossly overcharged to me-- and experiencing high pressure cut-outs--- or he has air in the system from never pulling a vaccum before charging...
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The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......
mrjoeyman on Sun August 21, 2011 11:16 PM
QuoteOriginally posted by: TRB
How much refrigerant is in the system? Why do you think the condenser is plugged?
Well if I knew I was right I wouldn't be asking. I only posted what I surmise to see if I was on the right track in this learning experience. I thought the low side pressure indicated that it was normal and that it wasn't overcharged with refridgerant. I did indeed have someone look at the ac when I bought this car a few months ago. The person I bought it from said that they didn't use the ac because it didn't work right. I took it to my mechanic and asked him to look at it and see what he thought. He told me that an ac hose had rubbed against another surface until it had gotten a hole in it. He said he replaced the hose and now that it worked. I didn't know a lick about this stuff at that time and just assumed that he did whatever a mechanic does when he fixes an ac. The ac from that time on worked pretty well, although never as cold as it should be until about a month and a half or two months later when it started to get less and less cold. I told the mech again about it and he said he needed to add another can of refridgerant and that I should get the leak that was letting out the refridgerant out fixed soon. He added the stuff and well, you know the rest. I started to read up on this stuff and now know much more about it; so much so that I wish I had not let the mechanic work on it from the get go because as good as his intentions were, I don't think he "goes by the book" on the ac repair since he is not an ac mechanic. After reading up on much of this forum and others, I purchased a good manifold gauge and checked my pressures and proceeded to post what I found right here to see if I can indeed learn how to fix my own problem through discussion and diagnosis. From what I gather in your replies, I should evacuate the system (fix any leaks of course) and make positively sure that the system is charged up with the exact refridgerant capacity (625 gms +/- 25 or 22.04 oz) and then go from there? Thanks for prompt attention!
PS TRB: These following reasonings by me are what lead me to surmise that the condensor might be clogged:
I read other problems similar to mine that were fixed by repairing the condensor fan. My fan works fine so I figured that the condensor may be semi clogged to the point where even the outside flow air from driving speeds were not enough to produce sufficient heat transfer from the condensor to the air. Of course I was assuming (and you know what that does :0) that there was sufficient refridgerant in the system due to my gauge reading on the low side. Obviously much more to learn here. But since you asked...
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~Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you're a mile away and you have their shoes.~
Edited: Sun August 21, 2011 at 11:47 PM by mrjoeyman
TRB on Sun August 21, 2011 11:53 PM
Yep, you have to start out knowing you have the correct amount of refrigerant. As well as the system charged after the system was pumped down like GMTech suggested. 40/400 are both high if you have the correct refrigerant level. If you don't it's just a wild goose chase to figure out what the issue might be.
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Contact: ACKits.com
mrjoeyman on Mon August 22, 2011 12:21 AM
Thanks. When I get to that point I will return with my findings.
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~Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you're a mile away and you have their shoes.~
HECAT on Mon August 22, 2011 6:57 AM
As part of your diagnosis and repair strategy (before recovery and recharge); I think it would be important to know what "stuff" your mechanic put in there (I.E. specifics from the labelling).
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JJM on Tue August 23, 2011 12:01 AM
The guy can't be much of a "mechanic" if he's charging by cans. A pro does NOT use cans, and how did he know the system "needed another can" just like that? In some cases, a 12 or 16 oz "can" is the whole system charge. He knows, there's a leak, yet he doesn't find or repair it? Now what's with that? A leak that large should be pretty easy to find. And while EPA 609 does not require leaks to be fixed, some states do. Keep that guy as far away from your Accord as possible.
To check if the condenser is plugged, you need to measure the inlet and outlet temperatures on the condenser, and also check for any cold spots on the condenser. If ice has formed, the condenser is definitely plugged, but your pressures don't seem to indicate that kind of restriction.
More than likely, judging from the repair techniques employed by this so called "mechanic" the system wasn't properly vacuumed down, probably over oiled, and the refrigerant is contaminated.
Joe
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