1st Time Recharge - How are my pressures?

[Tshark299]

So over the past 2 days I went from knowing nothing about AC systems to being very well read on them thanks to this forum. My system was converted to R-134a some years back by the previous owner and recently had started cycling every couple seconds first only at higher RPMs, then at idle as well.

So I got manifold gauges and a 12oz. can of 134a and learned how to add refrigerant through the threads on here. I'm just not sure if my final pressures are good.

With outside temps around 85°F and engine RPMs at about 1500, the compressor was no longer cycling and my pressures were about 40 on the low side and a little under 300 on the high. I let it run about 10-15 minutes like this, afterward the low had dropped to about 30psi and high was just over 300. The compressor ran continuously the whole time.

So how good or bad are those numbers? I found one chart of low pressure ranges for given temperatures by searching but there was some debate over the quality of the chart later in the thread. So how am I doing so far?

 

[Maniak]

Those numbers look good to me for an explorer r-134 system.

What center vent temps were you getting at idle and at 1500 rpms with the fan on 3 (not fastest setting)?

Also, since your a 1993 you probably don't have the heater control bypass valve (I think they "started" putting those in in 1994). With the heater control bypass you can keep the hot water out of the heater core which will help your a/c get even cooler.

There are a few threads on here about adding it. Its very simple to add. Just cut 2 heater hoses, put this in its way and run one vacuum line from under the hood to under the dash.

~Mark

 

[mrboyle]

I know this is an older post, but your high side pressures are way too high. You should be down around 200psi on the high side, 250 max. The most common cause of high readings on the high side is lack of proper air flow across the condensor. Try blowing the dirt out of the fins from the radiator side forward (I made a special blow gun that can go betweeen the condensor and radiator just for this). Also make sure there is nothing blocking the air flow across the condensor (pack rat nest, leaves, etc...) as well as making sure the cooling fan is intact, the clutch is working properly and the fan shroud is intact. If none of this drops the high side pressure you likely have some blockage in the high side of the system. Personally, if that is the case and the system is working decent I would just let it go, but be aware that it may fail at any time once tha blockage becomes worse.

 

[Glacier991]

I would add that in a converted system, with an r-12 condensor, the high sides tend towards those numbers. In gfact the biggest problem in a converted system if often the high side, prompting some to add high side blowoffs.

Simple truth, they work but the R-12 system condensor is too small.

 

[Tshark299]

I would add that in a converted system, with an r-12 condensor, the high sides tend towards those numbers. In gfact the biggest problem in a converted system if often the high side, prompting some to add high side blowoffs.

Simple truth, they work but the R-12 system condensor is too small.

Good to know, thanks!