Hi:
I purchased a 2004 Lariat 5.4 about 6 months ago. The a/c blew only cool. I put in 2 cans of 134a to get the low side up to pressure. It helped some what. It has been hot. I purchased another can and brought it to max pressure on low side per directions. No help. I purchased a set of gauges and found the low was 45 at 100 degrees out and the High was 450-475!!! Cyckes every 5 seconds on the freeway! Something must be plugged. I am going to change the orifice valve (thinking about the variable valve-thoughts?) and accumulator,o rings schader valves and caps (possible the compressor based on the material blocking the orifice. Any thoughts to help out there? I have bought the dvd and the a/c book from Autozone and the Haynes book for my truck. Some say after blowing out the system to put 1/2 the 9 oz. need in the accumulator and the other half in the pump. Another says all in the pump. What is correct? How would you or have you done it? The cans of replacement 134a all have oil in them (I think that is why I am having problems, too much oil). How can you put half of the oil in the pump and half in the accumulator and then ad freon and end up with 6 more ounces of oil? I was told the leak detector fluid also counts toward the oil total, so it must be critical. Any help anyone can give to give me direction on any of this would be greatly appreciated. I have looked around the web and even on you tube and the oil situation just is not answered. Please help as the heat is killing me!
Thanks again for any help.
Don

 

Does the freon you are using have leak detector? I like the low side to be a little on the low side of spec. I have never thought about the oil level too much start new and get the oil close.

 

The unit comes from the factory with a leak detector fluid in it. It must have leaked out years ago as I used a black light and found no evidence of a leak.
Don

 

Sorry I mean (stop leak)

 

The 134a is Arctic Freeze Ultra Synthetic and it says that it has an advanced leak sealer in it. I do not see anywhere on the can not to use in an orifice tube system. It was the only type of 134a that Autozone had. Are you thinking that the system might have been low in the beginning and that the leak sealer sealed part of the orifice tube? Any suggestions on how to proceed?
Thanks

 

It sounds like to me the compressor is worn out and now that its overcharged the pressures are way out of wack. You need to evacuate and recharge the system with the correct charge and check both high and low pressures. At idle the low should be between 30-45 and the high 225-275. Make sure the clutch fan is working it should be able to easily hold a piece of paper on the condenser. If the high is low and the low is high then the compressor is worn internally.

 

Evacuate then recharge PROPERLY. You're overcharged now and it's masking whatever the original problem is.

Your system is now cycling from the overpressure side. There's probably nothing wrong with the compressor if it can make > 450 psi. However, you likely have a condenser problem which might be as simple as insufficient airflow.

 

I think a lot of problems are started by "stop leak" refrigerant and avoid it in my stuff. Call around and try to find some without try some dealers.

 

I would like to thank all of you for your posts. I went to a shop and told them to lower the low side pressure to around 30-35 lbs. at 2000. Now with the outside temp at 95- the air output temp is 50! Thanks alot for all the help.
Don