A/C retro problem

[Robert_1967]

ok, I haven't really worked on a A/C system since the late 80's when I was in school, then working for a company installing heatpumps, and servicing them.

That be typed, I have a 89 BroncoII, it has/had the R12, and the system was open when I got the BroncoII, so this week end I went to Knoxville, and bought a set of gauges, and a vacume pump,, I pulled my system in to a vacume and let the pump run all night, 7 hours, I then let it sit for 2 hours to see if it leaked out, and it didn't, so I go and start chargeing it with a 40 dollor retro kit, right after the first can, the high side hose burst on me, the hose in the past had made contact with the compressor and ate the hose a bit on the underside, so I go out and buy a new hose, and while at the store, I bought a new accumalater/dryer, and orfice, r-134a oil, and all new o-rings, might as well do it right this time.

When I got home with my bag of goodys, I took my condenser out, and had it boiled clean at a rad shop, and also picked up a few cans of flush out, after cleaning out the evaperator, and the remaining hose's, I installed the new orfice (the old one was clean), reinstalled my condenser, then installed the new accumalater (spelling sucks), then pulled the system down into a vacume over night again, then let it set for two hours checking for leaks, I went to set up to gauges and found out I couldn't use the high side gauge, the retro piece was on the old hose, and does NOT want to come off, so I charged the system useing just the low/suction side, my system will get cool, but not cold, for some reason I couldn't get the suction side over +6 degree on the 134a gauge, my father-in-laws system was low and I charged his to +15 and it will freeze you out, but I first put in 3 can's, this to me seemed like too much, but it sill wouldn't go past +6 degrees, and when I picked up the RPM's to 2k it would pull down to 0 to -1 degree, now this isn't in a vacume, I put a 4th can in standing back, wondering what was going to blow first, hose or compresser, I have been running it like this for a few days, and like I typed, it gets cool, but not cold, I know it won't do as good as a 134a factory system, but I think it should do better.

does anyone have any ideas what could be going on with this and the low suction side?? I know the gauges are good, I had theem checked with the guy I use to work with backin the late 80's, he said for a 50.00 set they where pretty darn good, and on the money with the set he has that he paid 250.00 for.



Robert

 

[4x4junkie]

Low side pressures alone tell extremely little about what is going on with your system. You need to get that piece off your old hose (or get a new one for it) and hook your gauges up properly so you can find out what's going on with it.


Also, the vacuum pump only needs about 30 minutes or so to remove any air & moisture in the system (even less if you do it while the engine is warm). It's checking the system's ability to hold a vacuum that should be done longer (I'd give that part 24 hours myself).

 

[Robert_1967]

when I was in school back in 85-86 in voc school, the teacher always said to let it pull as long as possiable, but the system isn't leaking, so I guess when I get the chance, I'll buy another set of retro dohickies and hook up the high side and see what it says.



Robert

 

[4x4junkie]

Definitely doesn't hurt anything to do it longer (well, aside from some wear on your vacuum pump). Provided your pump is a decent one (pulls an equivalent of at least 29 in-Hg at sea level), all the moisture should be out of there after 20 mins or so, especially if you do it while the engine is warm.

Yeah, post back when you get the high-side reading. Also note the exact air temp coming out of the center-right dash vent on high fan speed (set to max cool), and the outside ambient air temp.

 

[kimcrwbr1]

If you don`t have a manometer to measure how far it pulls down the best way to check for leaks in with nitrogen pressure. The reason you vacuum the system is to put it in a deep vacuum and the water dont boil turn from a liquid to a gas until you reach 850 microns and just a small leak can prevent that from happening. A single drop of water can destroy the compressor so you need to measure the high side as well as the low side. did you check for leaks with soapy water on all the hoses and fittings. I would say get the low side between 35 and 40 and measure the temp going into the blower and the closest vent coming out that is the delta-t should be around 30 degrees.

 

[kimcrwbr1]

Oh yea find out what the original charge is by weight and estimate what you put in to get it close.

 

[Robert_1967]

If you don`t have a manometer to measure how far it pulls down the best way to check for leaks in with nitrogen pressure. The reason you vacuum the system is to put it in a deep vacuum and the water dont boil turn from a liquid to a gas until you reach 850 microns and just a small leak can prevent that from happening. A single drop of water can destroy the compressor so you need to measure the high side as well as the low side. did you check for leaks with soapy water on all the hoses and fittings. I would say get the low side between 35 and 40 and measure the temp going into the blower and the closest vent coming out that is the delta-t should be around 30 degrees.

I guess you didn't read the whole posting, go back and read, I don't mean to sound like a jacka$$, but please go read the whole posting.


Robert

 

[kimcrwbr1]

Sorry just trying to help yes I read the whole post and was just making suggestions you shouldnt post if you gonna do it your way anyway. GL

 

[Robert_1967]

Well, I found my problem, the Auto Zone sold me the wrong orfice dodad, they sold me one for a 134a factory system, I replaced it with the old one, and now it works great, I have it running at +15 degrees on the suction side, and now it get colds quick, and will try and freeze you out.

I didn't know there was a diffrence in the orfices.


Robert

 

[4x4junkie]

What exactly do you mean when you say it's running at "+15 degrees"? (sorry, I'm just used to pressure readings in PSI, which IIRC should be around 35-40 PSI on the suction side of a properly running system).

 

[Robert_1967]

that is what the pressure guages has for the 134a gauge, if I use the smaller inner lines it is around 40 to 45 psi.
I also have one of the throw away gauges that come with some of the cans, and that is what it is also showing, and according to my old boss, 40 to 45 (or +15 degrees) is where I should be at with a r-12 system retro fit to 134a.

I just know that now my A/C gets nice and cold.


Robert

 

[4x4junkie]

Ah, OK. Different scale on the gauge.

Cool. Glad you finally got it all working.