A/C questions

[no mufflers]

today it was about 95* over here so I got to do a good test on the a/c. well I was driving around and the air was barely cold from the vents. so I went back to the shop and hooked it up to the a/c machine, it was a bit low on Freon. I sucked it all out and pulled a vacuum, well I had one fitting that was loose so I found one problem. fixed that and finished the charge.

my machine says the system takes 2.38 lbs, so I put that much in. all the a/c parts have been replaced so the system is like new.

here is a picture of the temp I am getting. this was after a 15 or so minute drive at about 40-55 mph. while I was there I pulled the fan added some oil to the fan clutch. it did seem to work, the engine temp went down but the a/c was not effected. I can also hear the fan a bit more also so I know it is working more.

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I had a 06 chebby 1500 in the shop today also so I checked the a/c out on that. the a/c was much colder and I noticed the drier was MUCH colder. mine gets cold but from the touch the chebby was a lot colder.

now im not sure if that means anything or not. maybe I need to put more Freon in the system? I just think the air should be colder then it is.

 

[79jasper]

I'm sure the 2.38 oz of Freon was a typo.
Lbs?

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[no mufflers]

I'm sure the 2.38 oz of Freon was a typo.
Lbs?

Sent from my SAMSUNG-SM-G935A using Tapatalk

oops, thanks. ill fix it.

 

[79jasper]

I was about to say, well there's your problem. Lol
How do the actual pressures look?

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[franklin2]

I can't tell if your system is performing properly from here, but I can tell you that A/C systems do not have a set outlet temperature. They have a set "offset" temperature or a set differential temperature. They probably have a fancy name for it, but it's rated to cool the incoming air a set amount, that is it. Let's say it's 30 degrees. So if it's 70 degrees outside the outlet temp can be 40. 80 degrees, the outlet temp will be 50. 90 degrees the outlet temp will be 60.

 

[gnathv]

Need your actual pressures to be able to tell if your fully charged and flowing freon without restriction. I fought my 134 conversion on my 93 until I put a variable orifice tube in it. It then performed like my 97 which came with 134. 30 degree difference from inlet to outlet would be close, do you know what you have?

 

[no mufflers]

I forgot what the numbers were on the gauges, il look again later.

I was told the same thing about the temp differential from a good a/c guy I know.

Il check the numbers and maybe add a little and see what happens. I was told too much Freon it won't work and too little it won't work.

 

[gnathv]

That's right. You also have to have proper flow, if your orifice has crud in the screen, you will see higher pressure on the suction and poor cooling. Your evaporator never reaches saturation before your high Side climbs too high. Your high side should be roughly 2xoutside temperature minus 20. Is your accumulator condensating bottom to top or halfway up. Is your condensate a good puddle underneath?

 

[laserjock]

My notes say 32 oz of 134 and 7 oz of oil.

 

[Hydro-idi]

Mine was doing the same thing. Turned out there was way too much pag oil in system and the orfice tube was crudded up. Replaced that and refilled system with proper amount of R134A made a huge difference.
Your supposed to replace the ac drier every time you open the system up from what I've heard. Just my .02

 

[no mufflers]

I have a new evap core, orifice tube and drier. there is a fair amount of condensate that comes out of the box. the accumulator looks to be all wet. its just one from the parts store. I still have the factory unit, should I try that?

is there a round number I should be looking for on the HP and LP side when I hook up?

 

[chris142]

Pinch off the heater hoses and see if it gets cooler. Look for 2.0-2.2x ambient on the high side. 20-45 on the low. Should cycle on and off with the fan on low.

 

[junk]

couple comments

1. I would expect 40 degree or lower air out of the vents when driving. At idle if it's really hot and the cooling stack is heat soaked it might be higher. But not as high as you're seeing.

2. Pressures - I would expect High side to be over 175 up to 300-350 even and low side to be under 40.

3. The pressure switch on the drier can be adjusted lower. If you hook up gages see what low pressure the ac compressor is cycling on and off to. Inside the pressure switch is a screw that you can turn in or out to adjust the pressure I don't remember which way does what. Or go buy the R134 version of it at the parts store. You can change it with the system charged. I like them to cycle right around 35 degrees if I remember right. If you get it too low you start freezing stuff up.

4. I've also read to charge the system until the input and output fittings on the evaporator are the same temperature. Basically getting the evaporator in the dash fully cold soaked.

5. These systems take a lot of freon. So having to add more than you expect isn't crazy. I've started charging my truck by temps. My cars and other vehicles that take 2lb or less of freon seem to charge by weight better for me.

Good luck - sucks sweating and driving.

 

[junk]

Should add. If I pop open a system to do work I've had good luck not changing the dryer, but making sure to pull a good vacuum to remove the water from the system. Not saying it's text book, but I've had good luck with that.

Now if I'm doing major work in a system I replace the dryer.

adding a valve in on the heater hoses from a ford explorer and attaching it's vacuum lead to the white vacuum hose under the hood helps also. When on max ac it kills the heater flow in the cabin.

 

[no mufflers]

Pinch off the heater hoses and see if it gets cooler. Look for 2.0-2.2x ambient on the high side. 20-45 on the low. Should cycle on and off with the fan on low.

thanks guys..

when I did the heater control swap I adjusted the door to favor the cold function. you can hear it thump when going to cold.