overcharged AC
Thread Starter
|
Fleet Owner
Joined: Mar 2003
Posts: 24,724
Likes: 74
From: Blue Hill Township
overcharged AC
What are the symptoms of an overcharged AC system?
I converted my 92 explorer to R134a and I believe that I might have overfilled it. The gauge set is showing just under 100psi with the engine off, but the compressor is cycling on and the air blows at about 70-80 degrees. This would tell me its low, however I have put in 3 cans which is supposed to be over full. I am confused, help!
I converted my 92 explorer to R134a and I believe that I might have overfilled it. The gauge set is showing just under 100psi with the engine off, but the compressor is cycling on and the air blows at about 70-80 degrees. This would tell me its low, however I have put in 3 cans which is supposed to be over full. I am confused, help!
Elder User
Joined: Sep 2004
Posts: 941
Likes: 4
If you have too much refrigerant, duct temps will be too warm, not too cold.
The refrigerant has to be able to expand fully from a liquid to a gas in order to extract the most heat. An overcharged system leaves too much of the refrigerant as a liquid and you don't get much cooling.
100 PSI engine off sounds too high. A correctly charged R134a system runs about 70 PSI engine off as I remember it, but this is a bad way to estimate charge.
The real test is with the compressor cycling. The low side should cycle between 25 and about 45 PSI. The high side should reach a max of about 2.5 times the ambient temp. The compressor cycle should be about 7 seconds on, 10 seconds off at "reasonable" ambients (say below 85 degrees). If the cycles are longer than that, the system is overcharged. If the cycles are shorter than that, the system is undercharged.
The refrigerant has to be able to expand fully from a liquid to a gas in order to extract the most heat. An overcharged system leaves too much of the refrigerant as a liquid and you don't get much cooling.
100 PSI engine off sounds too high. A correctly charged R134a system runs about 70 PSI engine off as I remember it, but this is a bad way to estimate charge.
The real test is with the compressor cycling. The low side should cycle between 25 and about 45 PSI. The high side should reach a max of about 2.5 times the ambient temp. The compressor cycle should be about 7 seconds on, 10 seconds off at "reasonable" ambients (say below 85 degrees). If the cycles are longer than that, the system is overcharged. If the cycles are shorter than that, the system is undercharged.
Thread Starter
|
Fleet Owner
Joined: Mar 2003
Posts: 24,724
Likes: 74
From: Blue Hill Township
Excellent info guys. I have to exchange my gauge set as the high side hose literally blew up, but I will be doing that tomorrow or Thursday. I suppose the next step is to completely evac the system and put a vacuum on it and start from scratch. 
Post Fiend
Joined: Feb 2003
Posts: 6,940
Likes: 2
From: Eastern WA
The next step is to hook up your gauges and with the A/C on and engine running at about 1,200 rpm, bleed off a few ounces of refrigerant at a time until the low side pressure is back in the correct operating range. This assumes that the system was properly evacuated before the current charge was inserted. BTW, the pressure with the engine off is basically irrelevant to correcting this problem. All it shows is that there is *something* in there, but it doesn't indicate correct/incorrect charge.
Thread Starter
|
Fleet Owner
Joined: Mar 2003
Posts: 24,724
Likes: 74
From: Blue Hill Township
Well, I recharged the system and its still not cooling right and the compressor is still cycling too often. I went over the factory service manual and it looks like the evaporator or orifice tube is plugged. I just don't want to sped the money for a new evaporator and another $20+ on refrigerant.
Trending Topics
Hotshot
Joined: Jan 2004
Posts: 19,760
Likes: 1,079
From: St Louis
Originally Posted by MisterCMK
Well, I recharged the system and its still not cooling right and the compressor is still cycling too often. I went over the factory service manual and it looks like the evaporator or orifice tube is plugged. I just don't want to sped the money for a new evaporator and another $20+ on refrigerant.
Asking again. What are your readings? Whata re the ambient test conditions? Did you follow correct preparation procedures for testing?
If you want assistance, you have to answer questions that request relevent information. None of your information has been useful in understanding what is wrong.
If you just want to document whatever you're doing stumbling around, start a diary.
Steve
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Posting Guru
Joined: Nov 2004
Posts: 1,137
Likes: 2
From: Asheville, NC
Have you checked to see if the evaporator is plugged with leaves and crud?
Pull the blower fan and feel around inside there. Get all the dirt and leaves that you can, then using a crevice tool on a vacuum cleaner, clean out the rest of the crud. It will often make a big difference.
My '83 was loaded with leaves.
Pull the blower fan and feel around inside there. Get all the dirt and leaves that you can, then using a crevice tool on a vacuum cleaner, clean out the rest of the crud. It will often make a big difference.
My '83 was loaded with leaves.
Thread
Thread Starter
Forum
Replies
Last Post
perryau1996
1987 - 1996 F150 & Larger F-Series Trucks
9
Aug 28, 2014 09:39 PM
Schuby
1997 - 2003 F150
13
May 10, 2014 05:53 PM
Muddy86F150
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
12
Mar 26, 2010 07:15 PM
