Air Conditioning gods needed.

[cowman79]

I decided this year that I would fix the leaking AC in my truck. So i determined the leak to be coming from the fill valve on the high pressure side. So I ordered new adapters for the low side and high side. After I installed them I vacuumed the system down for an hour and filled it with freon. I noticed that the system didn't take the full amount of freon that it should have. After installing two cans 24oz total my low side pressure was reading around 45 pounds and the high side was reading around 250 pounds. The system was cooling the air down to around 68 degrees. I was never able to get the temperature any lower even with adding any more freon. I will say that last year I added some stop leak to the system to try and seal the leak. I believe the system was dry all winter because I added a can this spring and after about two weeks it was completely empty. My guess is that my system is fouled and needs a good cleaning and a new orifice tube along with a new drier because i am sure it is full of garbage.

 

[lindstromjd]

It's not about how long you vacuum it out, it's about how well it holds that vacuum. Take everything apart, put all new seals in everything, put a new orifice valve in it, put a new drier on it, and then hook it up to a vacuum tester. Then put your oil in, and charge with freon. R-134 is different volume than R-12. I believe it's .8 times as much (someone will have to verify that) R-134 as what the system calls for with R-12. So you're putting less 134 in it than you would put 12 in.

If you over-charge your system, it will work like crap. If you under-charge it, it will work like crap. Don't use the bottles. Use a machine. This is all just from personal experience... I am in no way an expert in a/c systems.

 

[cowman79]

Thanks for the info. This was what I was leaning towards. I let the system set for a while sealed up under vacuum and it didn't leak down. I added oil and recharged it with r134a which is what my truck had originally.

 

[Danielle]

Sometimes when I get in a vehicle with an ac system that's been leaking/empty/not working for a long time, recovering more than once, add oil, let sit, then put in exact amount will work. The other thing that has been interesting is the slight differences in what Mitchell says for fill vs sticker (if sticker even there).

 

[cowman79]

Yes the sticker is there. I believe it said to put in 2 pounds of r134a. SO when you say recover it twice does that mean pull vacuum on it twice or fill it run it, recover and refill again?

 

[jhnlennon]

Have you tried running a garden hose over the condensor to see if the pressures come down? Lack of airflow from a non functioning fan clutch will cause high pressures...

 

[cowman79]

I actually felt like the high side pressure wasnt high enough. I just charged a mustang a couple of days ago and when i charged it the low side was around 45 and the high was 350 and the air temperature in the car was 54 degrees. Both of these were older R134 systems. I dont know what the pressures should be on a sytem I guess I need to find a chart with that information based on ambient temperature.

 

[typ4]

Putting sealer in an ac system is as effective as patching a bald tire.. also really messes up recovery system filters.

 

[cowman79]

I realize that the stop leak is not a good idea. So now I just have to try and recover from a sealed(gunked) up system the most cost effectively as i can.

 

[gingrass179]

35 and 350 is good and yes vacuum fill cycle recover vacuum fill cycle and it does sound like possible expansion valve problems and accumulator should always be done when system is opened...and like said before I would do a complete tear down and reseal with new valve and accumulator...45 is a bit high I think for the low...

 

[cowman79]

On the high side I never seen over 250. This air conditioning service and repair is something new to me so I am learning as I go. So as far as fill cycle and evacuate and fill again I would want to take it and have that done because I don't have a recovery system. Just wondering if this is the route I should take or should I replace the accumulator, orifice tube, reseal, evacuate and fill again.

 

[PackRat239]

I actually felt like the high side pressure wasnt high enough. I just charged a mustang a couple of days ago and when i charged it the low side was around 45 and the high was 350 and the air temperature in the car was 54 degrees. Both of these were older R134 systems. I dont know what the pressures should be on a sytem I guess I need to find a chart with that information based on ambient temperature.

That high side pressure seems much too high. Must have a restriction in the system somewhere. I shoot for 50 or so low side and 250 or so high side. I have a big fan I have blowing on the cond if the weather is warm.

 

[cowman79]

The only only 350 was in a mustang I was working on earlier in the week that is cooling much better than my truck is. I can get 56 degree air from the mustang vs the f350 that barely gets below 70 degree air.

So what exactly causes an ac system to not cool properly. I am stil trying to uunderstand how and ac system works.
What I think I know is when there is a pressure drop with the freon it cause the temperature to drop.

 

[Sw1tchfoot]

It has to be really hot for my high side pressure to go much over 300 psi.

Maybe try blocking off the heater core hoses and see if it runs cooler, maybe your blend door is stuck and letting the hot air from the heater mix with the cool air?

 

[cowman79]

I will have to check the blend door.