my ac stopped blowing cold today and i have done ac work on my other vehicles i have owned but i cant remember what the high side and low side line presures are supposed to be. does anyone know?

 

Really depends on the outside temp and whether there is sufficient refrigerant, but 35-65 lowside and 175-250 highside are good margins. With the A/C unit on full blast, it is important to note if the compressor clutch is engaged and the center is spinning.

 

my cmpressor spins and engages just fine when it engages the low pressure line starts off around 40 psi and drops to 20 and the compressor clutch dissengages then the pressure on the low side increases to around 40 psi and it kicks back on when the low drops to around 20 the high side is around 300. i thought it was low on freon so i had a can and put about half of it in there to where the low would stay around 30 psi when the compressor was engaged but it still cuts off before it will start to blow cold air out of the vents really good like its supposed to. this was all around 80 deg f when i was messing with it but i wasnt sure what the line pressures were supposed to be so i didnt add to much freon because i didnt want to over charge it. and i had the ac controls on max with the blower on max.

 

Your lowside seems too low. I'm not surprised the compressor dissengages at 20 PSI. Your lowside should be about 55. However, your highside seems too high. Your compressor could shut off if the pressure is too high also. It sounds like you have 2 problems. The first, is your refrigerant is too low. The second, your highside is too high and most likely the result of poor condensor airflow. Spray a mist of water from the hose onto the condensor. If this solves your problem, then clean your dirty condensor with a coil cleaner. Most of the time I usually see folks with bugs, grease, and kinds of stuff plugging up the condensor. After that, try charging up the system a bit. Be very careful to avoid getting air into your system. Too much air is a sure HVAC killer.

 

i foound this info if anyone else is interested

Normal readings on high and low side with AC OFF (static pressure) - Depends on outside temperature, but normally is between 80-105 PSI
Normal low side reading with AC on high speed and MAX & engine at 800-1000 RPM’s - Ranges from 25-35 PSI - Note that on many Chrysler products a normal reading on the low side may be 15-25 PSI
Normal high side reading ranges from 200-350 PSI



A/C System Pressure Readings
Ambient Temperature Low Side Pressure High Side Pressure Center Vent Temperature
60 °F 28-38 psi 130-190 psi 44-46 °F
70 °F 30-40 psi 190-220 psi 44-48 °F
80 °F 30-40 psi 190-220 psi 43-48 °F
90 °F 35-40 psi 190-225 psi 44-50 °F
100 °F 40-50 psi 200-250 psi 52-60 °F
110 °F 50-60 psi 250-300 psi 68-74 °F
120 °F 55-65 psi 320-350 psi 70-75 °F


Clark's Garage © 1998

 

the first thing that i did was clean the condenser its not clogged up. but im going to put some dye in it and see if i have any leaks that i can find if i dont find any im going to evacuate the system check my orifice tube for clogs and debrea and change it out for the orange .056 orifice tube instead of the stock red .0605 and pull a vacume and recharge the system and see what happens.

 

well the orifice tube was the problem. pulled it out and it was comepletly clogged up with dirt and grit. changed it out with the orange tube not the stock red one and charged it back up and everything is good now it was 85 deg outside and i have 38 deg comming out of the vents on high.

 

here are pics of the clogged tube that came out of this truck that has never had the system worked on and is only an 06 model. hmm im wondering why the factory put all of this dirt in here and didnt clean it before they charged it up when it was made i wonder what else they do half *** on their vehicles?

 

Could the oraface tube be clogged and still get fairly normal readings on both high side and low side?

My truck is blowing warm air and the deler tells me the readings are OK...

I wouild suspect the orafice tube?

 

Usually when I find a clogged orifice tube, the low side pressure either slightly above normal or high.. IF your pressures are OK, sounds like you may have an air distribution concern possibly with a blend door or actuator...
What are your low and high side pressures, ambient air temp, discharge air temps?
How long is the cycle rate?

 

you get high readings on the low side? the port to test the low side is after the orifice tube on the dryer. so it would be to low rather then high dont you think?

 

no not really. the static pressure for the temperature would be right asumming the system is charged properly.
but when running the high side would look right but the low side would be really low around 20 psi then the compressor would cycle off the pressure would climb on the low side and the compressor would kick back on and do it again drop to around 20 psi and shut back off it would do this pretty quickly on off on off with it being off a little longer than on well depending on how clogged it was. but if the pressures check out right and the compressor is staying on for a little bit and the low pressure isnt droppin low enough to shut down the compressor and your line going into the condenser in the dash is cold then you have other issues.

 

i have bad news for you...thats not "dirt" its desiccant from your accumulator, dessicant absorbs moisture in the AC system and without it your in for even worse failures. You need a complete AC sytem flush and new accumulator and possibly even a new compressor by now.....

 

i havent had anymore problems with it since i changed the orifice tube. i did flush the system and no other dirt or (dessicant) came out of it that was it just what you see on the tube.

 

Thanks for all the help. Took it back to dealer the today (3rd time) . Only this time I asked the service manager to go for a ride.

He found a leak in the seal in the front of the compressor. They put in a new compressor.. A/C is ice cold once again and holding. He said it wasn't a good idea to try and put new seals into a compressor that has over 50K miles on it. More expensive for a new compressor ...but it did make sense.

I don't know why the reguler Tech's couldn't find the problem? (The service dept is not that busy) The service manger felt both lines with his hands... noted that the compressor was short-cycling.. and boom.. he said it was the seals in the front. I guess, moral of story.. when in doubt.. get the tech or a manager to go for ride and show them the probllem yourself.

So , thanks once again. Great pics of the orifice valve. At least I learned quite a bit about how A/C works... :-)