hey all you young people who still have your memory. i changed my 86 f150 to R134 about 15 years ago, and recently changed my evap. and accumulator, now with 250 lbs. hi press. and 35 lbs lo press. my accumulator is ice cold,but my air temp is 54 degrees. It was fine until my evap. busted.also I did use a new blue orfice. could a bad seal at the case halves cause this ? thanks

 

think 50 to 58 degrees is the best your going to get. My dealer installed unit I have it charged and running 275 highside and around 30ish low side and it puts out on a 100* day 58* out the vents and in the evening around 6pm when I am going home it will get down to 50*.

 

By "ice cold", do you mean ice is collecting on the outside of the accumulator? If so, that isn't good. Sounds strange, but ice is bad with an AC system. It means the refrigerant inside is not transferring heat properly. Even though air is passing over a very chilly evaporator, the ice actually behaves as an insulator. The result is duct temps not as cold as they should be.

Two main causes:

1) Low airflow through the evaporator. Every couple of years, I have to open the evaporator case and clean out the leaves and bugs that collect in there.

2) Low refrigerant. Please note gauge readings are NOT a reliable means to determine refrigerant quantity. The ONLY way to determine quantity is to do a full evacuation and recharge, using a measured amount. (For an R134a conversion, 80% of the original R12 charge is a good rule of thumb.)

Evac and recharge, that's the official party line. Now here's what I've done on many occasions, and this is straight from the factory manual for the R12 system. Add about 4 ounces and see if the cooling improves. If not, STOP. Low refrigerant wasn't the cause. Adding even more won't help, and could cause new problems if entering an overcharge situation. This part is hard to get across. I got reamed over this suggestion on another forum, but I swear by it. The important thing is determining if the extra amount of refrigerant improved the cooling, and stopping if not.

If the cooling improved, you're on the right track. Try adding another 4 ounces and evaluate again. When you reach the point where there is no improvement, it's time to stop. In most cases, that's all the fix you'll need. Sometimes, you could have a second problem in addition to low refrigerant. If so, you'll need to diagnose and repair that, too.

 

You can use pressure as a reliable means. High side is ambient air temp times 2 plus 15 and that's what your high side pressure is. I think its 15 PSI been long time since I used this formula. But for my truck I use it because there is no spec for dealer A/C capacity. So if your temp is 100 degrees ambient air temp high side should be 215 PSI in theory. But this here can be effected by lack of air flow if you place a large fan infront of your truck you can get high side pressures to go down. My truck is 275 PSI high side at idle but once you start getting more air flow its tarts to drop towards 250 PSI.

 

I've got to respectfully disagree with that. I have the factory AC on my truck and I converted it to R134a years ago. I'm running an orange orifice tube and added a vacuum-controlled heater shutoff. It will blow 38 degree air all day long at cruising speed even with ambient temps in the 90s. It's not quite as efficient in stop and go traffic (45 degrees output), but I can live with that.

 

Heres the thing, you've changed numerous things on your truck. I am talking about in stock form. I didn't change my orifice tube and even if I did being dealer A/C mine wont blow colder as the cycling switch shuts off at 40* and when that happens duct temps wont be much below 60* on a very hot day. Plus a hot water valve in mine wont make a difference as my A/C is completely mounted behind my dash which is way more efficient than the factory setup that sits under the hood.

 

thanks for the replies. it isn't forming ice, it is just real cold from the evap to the compressor, the air in the cab isn't as cold as it was before I 'fixed it'. I used gasket maker on the case halves, so i'm thinking it's drawing hot engine air thru A bad seal.

 

Or one of the air doors is leaking in the duct. These trucks do not have a water valve on the heater core, so the heater core is hot all the time.

There is a modification you can make if you think the heater core is affecting the temps and you have a door problem. You can buy a vacuum operated water valve for a ranger(I think it was a 90's ranger). They are about $15 if I remember correctly. Cut the heater core lines and install it, and then buy a little vacuum tee and tee into the vacuum line going to the vacuum motor over at the pass side hinge. Then when you put the system on AC Max, there will be vacuum on that line to move the motor to recirculate the air, and it will also cut the water off to the heater core.

 

thank everyone for their input, but i didn't do enough checking before i posted. those pressure readings were at idle.at 1500 rpm they change to 275/25. cycling switch turns it off & on rapidly.if i put a jumper on the switch it will pull down to 20. i am going to look for a restricked cond. scince i found metal shavings in my old orffice. wish me luck.that rebuilt compressor is 15 years old i never had one to last that long !