Thread: Any A/C experts out there?

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Originally Posted by Stu Cool

Wow, make a post and spend the day at a Blues Fest and come home to 11 replies. You guys are the best!

Here's a little more info. The systems is all rated for 134A, ambient temp was about 90, 36-38 degrees was with windows up on high, recirculating inside air. The compressor was evidently shipped oiled as it had a sticker on it that siad DO NOT ADD OIL.

I am thinking I do have a restriction or a bad/clogged expansion valve. I will call Southern Air on Monday and ask them about a replacement.

I will keep you posted about what I find.

Pat

if your system is cooling down to 36 degrees there is no restrickens. on a hot day 250-300 lb. hi side is not to high, and if its cooling at 15 lbs. low side then thats great. most comp. make noise when they cycle, and other wise the belts can make dif. noises. as far as the ac goes if you drove it any dist. yesterday and it cooled and didnt ice up, i dont see a problem. if you dont have the proper mufflers in the hose you'll get all kinds of noise. sucking and pumping.

Stu,

Glad you had a good time at the run. Thats what this is all about!

As a follow up on this post, I wanted to stress again that my friend says forget conventional wisdom about stock A/C systems due to the fact these aftermarket systems work differently. This really hit home when he told me the low side should be between 6-12 psi. I immediately responded "that sounds too low to cool at the temp I want". He then reminded me to forget stock systems which have larger capacity systems.

Here is a link to the Trouble Shooting guide found on Vintage Air's website which describes the expected low and high pressures. I would suspect Southern Air and Vintage Air's systems to be similar in how they operate with respect to pressure, so it should work for you as well...

http://www.vintageair.com/DownloadsS...ng%20Guide.pdf

Again, I am no expert, but so far my research points to too much freon is not a good thing on these street rod systems.

Stu Cool,

HTML Code:

 http://www.csgnetwork.com/r134apresstempconv.html

Heres a site with a interactive chart that you can enter different psi's for
134a and get the proper evaporator coil temperature.

And there is a lot of other information there on all sorts of suff.

Pat, I don't think that is your restriction, the restriction I'm talking about is on the high side, (inlet side) of your exspansion valve, where there is a small screen in their that gets plug up with dirt and prevents you valve from metering properly. If you are able to Isolate or disconnect the compressor on both sides high and low from the metering device, you can take a tank of nitrogen and blow back threw the exspansion valve on the low side to the high and most of the time you can open up the restriction.
Note: at 15 psi looks like a evaporator coil of 14.94 degrees F. I hope this helps.

Originally Posted by DennyW

Mike, that sounds like R-12 at 2500 rpm's, fan in front of the condensor readings.

no, i got those # off of a 1996 caddy that a new comp. (low side was 30)
was installed on last week, and i called the shop to see how it was doing sense it had cooled off some and he said it had been cooling great, but he hadn't checked the pressure anymore. it pulled down to about 50 degrees. if stu had a cooling problem i would agree with a restriction, but, 38 degrees ???? you should have cooling problems with restriction like "no cooling"

I was hoping that some one would say that.

I do not remember seing a stuck, sticking or clogged expansion valve that allowed the evaporator to cool enough to blow cold air out the vents.
Not saying I never came across it, but right now I do not remember such a case.

I still would like to know how much fluid was put into the system, and how much of that damn dye.