I charged it day a few days ago and converted to Freeze 12. And then I realized I had a leak at the low pressure switch and fixed it and recharged. So I don't know exactly how much I charged it. I had chagred it to 28 psi low side, 210-220 high side. It blew a chilly 38 degrees. It was high 70's. Today it would not get colder than 50 and I figured I had another leak. Checked pressures which were 35 low side and 250 high side. Of course today it's mid 80's but it should still blow colder than that. Am I overcharged? Been awhile since I had AC in one of these.
Are my A/C pressures too high?
- Thread starter disco stu
- Start date
- Joined
- May 28, 2001
Fan coming on when the A/C is called for??
Make sure your ac fan comes on as soon as you throw the switch inside the car. Was the refrigerant ever completely empty or were you just topping it off?35 psi is where I like my low side, but seems your high side is up either by the fan not cooling down the condenser or because you have air or other non condensible. Gases in the system.Did you purge the ac hoses when you recharged if not you may have entered air into your system causing a high head situation which would need recovery and evacuation before properly recharging.
DailyDrifter
The Slow and the Curious
- Joined
- Dec 5, 2007
I'm going to say orifice tube. But, did you vac the system first or just add the freeze 12? Did the system hold a vacuum? IMO that crap you get at autozone in the cans does nothing but put contaminates into the system. Some people have good luck with them, but I would still do it right.
Shoulda done the orifice valve while it was empty. 
Yeah, fan kick on with AC.
Yeah, I sucked thesystem down to about 10 in/hg for a half hour before charging it. And it did hold a vacuum. But still leaked. got that fixed, Pressure switch O ring. I got a high zoot leak detector that works well, and have not detected anything else.
It was back down in the mid 70's today and was blowin 40*.
Since I used freeze 12 I'm wondering How the hell I'm gonna get that recovered.
Yeah, fan kick on with AC.
Yeah, I sucked the
system down to about 10 in/hg for a half hour before charging it. And it did hold a vacuum. But still leaked. got that fixed, Pressure switch O ring. I got a high zoot leak detector that works well, and have not detected anything else. It was back down in the mid 70's today and was blowin 40*.
Since I used freeze 12 I'm wondering How the hell I'm gonna get that recovered.
xrunner123
Member
- Joined
- Oct 2, 2002
Air in the system?
Shoulda done the orifice valve while it was empty.
Yeah, fan kick on with AC.
Yeah, I sucked the
It was back down in the mid 70's today and was blowin 40*.
Since I used freeze 12 I'm wondering How the hell I'm gonna get that recovered.
You will need a seperate recovery system to take it out John. Blow it off first and then check the orifice tube. If it has a bunch of trash in it then the compressor is toasted. Freeze 12 won't lubricate the system like R-12 used to. It has a mix of stuff in it and it killed the compressor in my car a few years ago.
Me personally, get the R-12 or do the switch.
When you evacuate it, it should get pulled down to a 25" vacuum and hold pressure for atleast one hour-I like to do it overnight for a whole day to be sure there no minute leaks. Also when you recover the freon it's recommended to oil up all the o rings on all connections or change them out cause they dry out and crack causing leaks, even worse on R-134 cause the molecules are smaller and have more of a tendency to leak more. Hotshot or R 414B is a direct drop in without changing compressor, 20 degrees colder than R-12 and alot cheaper-used it for 5 years4 cars -no issues.
DailyDrifter
The Slow and the Curious
- Joined
- Dec 5, 2007
Some shops have machines that will take contaminated reefer. You will contaminate other machines if you recover it.
How did you pull the vac in the first place? A small vac pump maybe? Dont forget to add dye in the next charge to look for leaks
. Also you should pull it down to lower than 10in.hg to boil the moisture out of the system. I think you need different oil too with R134a. But I think your problem is a clogged orifice tube due to the high side having so much psi. I think the low side should be around 50-60
, maybe Charlie can answer this? I would say your compressor is working (for now) because its obviously putting out high psi, but the orifice tube wont let anything by... You might have the "Black Death" when you pull the tube out .high pressure doesnt mean the compressor is good. On the low side a strong compressor will pull down to 25-30 psi. Low side pressures around 50-60psi is not good. Usually means a weak compressor or low charge. If the pressures drop to near 30's under load (2k rpms) but go up at idle the compressor is weak. High side will vary depending on outside air temp and how much air is being pulled through the condensor. Very high pressure readings can indicate a restriction possibly from orifice tube or expansion valve depending on system style.(buicks=oriface tube) Make sure you pull a vaccum to at least 25in.hg.to get all air out of system. I am spolled at work using 10k dollar A/c machines. A/c work is so easy with these machines. You need a set of gauges to monitor and I prefer a scale to measure refrigerant amount going into system
50-60 psi on low side usually means overcharge not low charge, higher press=higher temp, lower pressure= lower temp-where you want it. If you want to figure out the high side pressure under any conditions use this rule of thumb-whatever your surrounding temperature is or ambient add 30 degrees to the temperature and it will tell you what the pressure should be-this formular is used on all air cooled condensers as what's in a gn.
Average pressure on a GM CCOT R-12 system is between 40 and 45 LBS on average for a single system. If it was a double system then it would be between 50 and 60 LBS. The fact that you have low pressure on the low and high on the high it shouldn't be the oririfice. If the tube was clogged then you'd have the reverse happening. High on the low and low on the high. You really need to take the orirfice out and see if there's trash in it so you can see if the compressor is trashed.
Ive charged so many cars over the years that have had high low press readings that were undercharged. So it is possible. More likely actually since there is no reason to have a overcharged system using proper equipment.
Heres a diag chart from GMDealerworld showing it.
Service Information
| Diagnostic Information and Procedures | Document ID: 884957
--------------------------------------------------------------------------------
Air Conditioning (A/C) Diagnostics - Pressure Zone B
DEFINITION: The low side pressure is higher than normal and the high side pressure is lower than normal.
• Malfunctioning A/C Compressor
• Refrigerant Under Charge
Heres a diag chart from GMDealerworld showing it.
Service Information
| Diagnostic Information and Procedures | Document ID: 884957
--------------------------------------------------------------------------------
Air Conditioning (A/C) Diagnostics - Pressure Zone B
DEFINITION: The low side pressure is higher than normal and the high side pressure is lower than normal.
• Malfunctioning A/C Compressor
• Refrigerant Under Charge
Looks like my compressor is toast. Lots of black gunk in
the orifice. So, should I replace my condensor too? This could get pricey real quick. What about the Gbodyparts compressor, dryer and orifice package? But I've read it uses sealing washers instead of o rings. Would this be a good way to go?
49 blues, I couldn't remember what the rule
of thumb was. But your saying my hs pressure should be 130 on a hundred degree day? Did I read that right? I don't have a way to
scale my refrigerant. Maybe I should just have a shop
charge it when I get the compressor and other stuff replaced.
Thanks for the replies guys. Lots of real good info.
the orifice. So, should I replace my condensor too? This could get pricey real quick. What about the Gbodyparts compressor, dryer and orifice package? But I've read it uses sealing washers instead of o rings. Would this be a good way to go?
49 blues, I couldn't remember what the rule
of thumb was. But your saying my hs pressure should be 130 on a hundred degree day? Did I read that right? I don't have a way to
scale my refrigerant. Maybe I should just have a shop
charge it when I get the compressor and other stuff replaced.
Thanks for the replies guys. Lots of real good info.
You can google for a refrigerant pressure/temperature relationship chart which will tell you temp at any given pressure or pressure at any given temperature, also can see this on any set of refrigeratant gauge set-the temp known will tell you the pressure unknown.
