been working on the A/C (original equipment). the PO said it just needed the blower motor replaced (which he had the part, but hadn't done it yet) and possibly recharged. Replaced the blower motor...and it blew warm air. the amount of air isn't anything to cheer about, but I didn't know if that was "normal" for these old systems. got it all put back together and charged it. It has been retro fitted to 134a. put 2 1/2 cans of 134a in it to get the pressure up to where it needed to be as well as a 4oz can of oil to help quite the compressor. more air comes out at the bottom of the dash under the ashtray than thru the vent (going to check this out tomorrow - not sure if the vent hose isn't attached well or what here). It does blow cooler. However, I read from searching thru the forum about a number of guys "blowing ice cycles" from their A/C...out in West Texas...we like ice cycles from our A/C...but right now, I'm lucky to get a shade over luke warm. any ideas as to what's happening here? The gauge shows its charged and full - so not sure adding more 134a is an option at this point.
thanks for the help!

 

I have messed with a/c systems since helping my Dad in his shop, literally 50 years ago. I have converted lots of systems to 134. Believe me, these trucks are NOT good candidates for conversion. The York compressors just won't hold up to the added pressure of 134.

In addition to the above, charging a converted 134 system can be tricky. Strike that, IS tricky. The high side pressure can run away.

Okay, now, what are your pressures and your ambient temperature?

 

R134 is not as efficient a refrigerant as R12 so in order to make up for this inefficience you must improve other parts of the system. The most important is the condenser. This is what transfers the heat to the outside air and perhaps the most important part of the system. Our old trucks use a serpentine tube condenser while new vehicles use a parrallel tube condeser which is much more efficent. You can buy universal parrallel flow condensers in many sizes. I would get the largest you can fit behind your grill. I would look around this site : http://www.ackits.com/
You will find a wealth of info and things you can do to improve your system and the prices are very competative.
Good Luck from a fellow Texan
Mark

 

mark... thanks for the input...hadn't thought about the condeser. I'll check into that. what area are you in?

doc... i know that the r12 is much better. I was hoping mine hadn't been retrofitted for that exact reason. but since it has, I'm trying to make the best of it. I don't remember the exact info, but I'm pretty sure that the low side was about 38. My brother was doing most of this part, so I couldn't tell you what the high side was. we didn't have anything to measure the temp at the vent. If I was guessing, I'd say mid to high 60's?? I can tell you we drove around for about 10 mins with all the windows up, about 85 outside, air on high, temp on cold, blower on high and it wasn't cooling us off.

I'll check with my brother this afternoon and find out what the exact low and high side pressures were and post back with the details.

thanks.

 

I too have experienced vent temps that are not as good as some others have posted. I recently went thru my system with a new York compressor and a new dryer, after flushing the system, and my a/c tech recommended charging with Freeze 12 instead of 134. Vent temps were running 50 to 60 degrees until I installed a heater shut off valve and they dropped to 45 to 50 which I feel was a great improvement. I am really considering taking the system down again and flush and recharge with R12 since the price seems to be getting a little more reasonable now.

 

You may need a new HVAC "vacuum" switch. It's the one that selects the ducts through vaccum motors.

 

I had some luck with my CC moving the temp probe on the restrictor away from the tube. Helped a little. Probbably raised the pressures but it hasn't blown yet.

 

Upgrade your AC Compressor to the smaller Sanden 508 5-cyl less drag. Trouble with 134a stop & go driving the system blow warmer when stopped then cools when moving.
Move condensor as close as you can" to 1/4" to 3/8" plug off any opens with foam rubber so you'll get as much draw through the condensor at eng idle.. If you open system the dryer must be plugged off so it don't get screwed up or if it's just replace it. It can only suck up so much water from the system.. my 2cent
orich

 

Tisk, tisk, tisk....

It always amazes me at the trouble and massive amounts of dollars that people will spend in order to save $50 or $60 in refrigerant cost!

To start with, stay away from the junk refrigerants such as Freeze 12, Duracool, etc., They all fall into one of two categories, an explosive or a blend. R12 has gone down in price due to the fact that the cars requiring it are hitting the wrecking yards in record numbers, decreasing the demand for it. You know, the old supply and demand pricing theory.

Secondly, upgrading the condensor is fine except AS I PREVIOUSLY pointed out, the York compressor will not stand up to the added head pressure of the other refrigerants.

Third, the Sanden is a great compressor, but how much R12 or how many $100 rebuilt York compressors can you buy for the many hundred dollar cost of converting to a Sanden?

The old York/Tecumseh a/c systems are very effective and very cheap to buy parts for.

Now, back to Fishers specific problems; Don't overlook the advice in this thread to make sure that the vacuum controls are working correctly making the air recirculate rather than trying to cool too much outside air. Fisher_Of_Man, if the pressures you reported are correct you either have an opened up expansion valve(not likely) or a bad compressor. Again, these compressors can be had rebuilt from many different sources for around $100. The compressor is most likely bad because of the use of the 134 which caused an increase in high side pressure that the York can not tolerate.

If you do not have any R12, you can go online to a multitude of web sites such as imaca.org and take an online, open book test for $15. You can then buy R12 from such suppliers as refrigerant.com or on ebay.

Here's my advice to you. Go recheck your pressures and if they are indeed 30's low and 60's high, replace the compressor or repair the valves in the compressor. Disconnect all lines and flush back and forth between all connections with mineral spirits or brake cleaner AND BLOW ALL OF THIS FLUSHING AGENT OUT OF EVERYTHING THOROUGHLY. After flushing, replace the compressor and lastly put in a new filter drier as the last item to seal up.

Evacuate the system thoroughly and then charge with R12.

Don't throw away several hundreds of dollars on a parallel flow condensor and many hundreds of dollars on a Sanden compressor so that you can save much less on refrigerant cost.

 

F.Y.I. I had my system converted at a local shop during the off season for $500. Included a Sanden and hoses. It works just as good if not better than the original system ever did. It also is a ton smother. You can hardly tell the compressor came on. I have a fast idle solenoid that compensates for the idle speed drop.

 

MB Diagman...thanks for the good info!

my brother is coming over tonight and were going to go back thru it all and check the pressures again. I'll check those things and then get back with you. I'd rather have the R12 because of its effectiveness, but I know that it's been retrofitted to the 134a. I'll check this all out tonight and post back with my findings.
thanks again!

 

just a quick update....we started looking at the A/C...and because of available time, parts, and tools, quickly moved on to other "issues". However, when we hooked the gauges back up, we had pressure on the low side of about 18...when you'd rev the engine, it dip down to 7 or 8. Since we were at 30 yesterday, we assume we had a leak. upon some further digging, we discovered a leak in the hose from the compressor to the condesor. Since we've already lost quite a bit of 134a, we are going to evacuate the whole system, replace a couple of hoses (if we can find them - autozone didn't carry them and Advance Auto Parts didn't have them, but might can order them). Also, the temp at the vent was only getting to about 70 (probably because so much of the 134a had leaked out). after this, we have pretty much decided to remove the 134a fittings and go back with R12. I'm hoping we get to do this on Saturday. Will get back to you with more details as I have them...anything i should be on the watch for between now and then?

 

You can get hoses redone at any automotive a/c shop or hose shop. They simply replace the rubber and recrimp.

If you decide to go back to R12, you need to break all connections, flush thoroughly, THOROUGHLY REMOVE ALL FLUSHING AGENT, change compressor oil, reconnect everything and the last thing you do before connecting the vacuum pump is to put in a new filter drier. This is not as much trouble as it sounds, and will be well worth it if you have a good compressor and have fixed the leaks.

You did not specify the high side pressure. You need to have both low and high side pressure for any meaningful diagnosis.

 

-update -
ok, we took of the hose from the low side hose from the compressor to the condesor. It had been leaking at the fitting on the compressor side ( a barbed fitting, with a clamp) and also at the condesor side (a crimped fitting - leaking around the crimp). couldn't find a replacement hose or anybody in town that would actually do the crimping. I know many of you have posted that anybody does this, but I talked to all our auto parts stores, several shops, and even the one place every one kept telling me to go. None crimp the hoses. I couldn't find a pre-fabed hose at any of the auto parts stores....so, we found the same 13/32 refrigerant hose at NAPA. got a barbed connection for the end that goes into the condesor (previously a crimped connection) and double clamped everything. put it all back together and evacuated the system. Pulled a vacuum on it at about 28lbs for 5 mins, let it off and the vacuum dropped to about 8lbs within 5 mins. Pulled the vacuum again and left it for 30 mins...still holding steady at 28 lbs. after this, decided that the system was good, so we start putting the 134a back in. the first can went pretty well...the second can acted like it didn't want to go in...got to the third and it went in....after that, our pressure on the low side was still about 12 and I don't remember the high side ... I think it was about 280. So, we decided to go with a 4th can. because we were out, decided to drive it to walmart to check things out as we went.

the temp at the vent when we left was 62F...drive to walmart (about 5 mins), get out do our thing, drive home...pull back in the drive and the temp at the vent is 90F. Put the 4th can in and the high side is right where we want it...about 375lbs....the low side...a measely 20...sometimes jumping to 25...the temp at the vent is 62 again, but no cooler.

we can't figure out what the heck is going on...and the low side is still too low. we want the low side to measure 35 -40....got the high side where we want it...and we still want the temp down to about 45 -50 at the vent...

also, when we were closing the valves back off after adding the 134a, the valve on the high side shot out a little when closing it...like maybe the valve was leaking? it hadn't done that before so not sure what's happening there.

I know some of you say go to this compressor or this condensor...but surely, we can get good cooling from what we got...without sinking an arm and a leg into the thing. I know R12 works better too...but right now I got the 134a stuff setup...so any advice on how to help with that is appreciated.

any ideas or thoughts?? thanks in advance!

 

At such a high, high side pressure, I'm surprised that a piston didn't come out the side of the compressor.