In response to Sean's post of 2227 yesterday - my experience with the conversion was that the R134 does not blow as cold as the R12 - although kicking the fan up a notch, or engaging the recirc function earlier still keeps things more than comfortable.

Did the conversion in '99 and replaced the O-Rings, drier, and orifice tube as recommended for the time. Compressor was making a bit of noise before the conversion, so I guess the change finished it off. Flushed the system, another new orifice tube, and a new off-brand compressor - been good to go every since.

Humidity plays a very large part in the feeling of cool. I think it's called latent heat in the HVAC circles, and has to do with the cooling energy required to condense the water which takes away from the total system capacity for cooling air. Here in Swampeast Misery - not unusual to see an almost steady stream of water coming out of the evaporator drain.

 

Exactly, the R12 system isn't designed to work correctly with 134a and therefore won't ever get as cool as a system that was designed for it. I don't feel like screwing around, I don't have a/c at all and if I'm going to the trouble of swapping the entire system on I'm going to take a 134a system. At least it should be relatively easy, these trucks had a 134a system that I can bolt right on. I've done much harder crap.

 

All right...resurrecting this thread in hopes I can figure out what's going on with my system. It's an R-12 converted to 134 by just adding 134. I converted it about two years ago, but that was just before I deployed for a year. So, I remember it working fine back then, but then I came home last October and didn't need a/c until this summer. To say the least, it's been a while.

About a month ago, I didn't think it was blowing cold enough (I like ice cubes), so I topped off the 134 from a pressure of about 38-40 psi to a pressure of about 45 psi (based on the gauge that came on the 134 can). I didn't notice a huge change, so about 2 weeks ago, I added stop-leak with red dye. Haven't seen any leaks. Then a week ago, I bought another can of 134 (thinking it had leaked out before I put the dye in) but when I put the can on, it still read about 45-50 psi. I squeezed the trigger a few times just for good measure, but still no changes in a/c temp.

Compressor runs fine, the tube where the orifice tube sits gets cold, and the evaporator drain flows freely. After reading this thread, I'm not sure where to go next. Too much oil in there? Condenser clogged? What do you think? I'm in Arkansas with near 100 degrees everyday and humidity.

Thanks!
Bryan

 

You won't get ice cubes out of that unless you're moving. Conversions seem to blow cold when you're moving but sitting still it warms up.

 

yep...
clean the condenser...ONLY add freon just until the compressor stops cycling at 2500 rpm then drive it...if you here it cycling add just a tad more...

134 gets colder the LOWER the pressure is not higher...adding more just makes it warmer up to the point you actually hydraulic the pump...

the reason it gets warm sitting still is too reasons...1 the system is old and in-efficient...even a 134 system will do this with age...the compressor is worn and it just doesnt move the freon like when the compressor is new

second...in order to cool you MUST remove heat from the condenser...there is very little airflow thru the condenser sitting still...thats why it gets warmer sitting still. Again even a 134 system will do this...

my 95 F150 would hit 50f sitting at the light up from 32f....I put 2-12inch fans on the condenser and run them sitting still and the temp stays at 32f sitting still...

you NEVER want to add oil unless you change the compressor...unless it comes prefilled..you only need 3-5ounces depending on the pump...any more oil than that and it cannot remove the heat as it stays suspended in the oil...and saturates the drier..I only add cans of straight freon..the ones WITHOUT the oil...

I just did a conversion on a Pontiac Bonneville...it got 45f sitting still and 34f down the road...thats almost like new temps...

the trick is to ONLY put enough freon in to get the compressor to stop cycling at driving speeds....I didnt even change the drier switch to the lower pressure switch.

 

Great! Sounds like a plan. Thankfully, I don't do much sitting around, and if I got 45 doing that I'd be thrilled. I'll try cleaning the condenser first, then if that doesn't work, I'll get a new compressor.

So, how do I clean my condenser? Just disconnect and flush? Or does it require special equipment?

Thanks!
Bryan

 

I think he means make sure it's not covered with leaves and crap. Make sure air has a clear path through.

 

yep Sean nailed it...yet again..

road grime, dust, bugs or anything and hinders air flow cause it not to remove heat...

when the car is cool...use degreaser like Simple Green or Purple Magic and spray it on full strength and keep it wet..let is soak 15 minutes and hose it off...

keeping the surface wet is the key and the longer it soaks the better....but you gotta keep it wet..

then hose it with water until it runs clean...or find AC coil cleaner at Lowes...for home AC coil units...but thats nasty caustic stuff...

 

Nice. Glad I was wrong! That's a lot easier than flushing it. I'll post back when I've done that.

Thanks!
Bryan

 

Well, I don't think it worked. I got some "Purple Power" degreaser, sprayed it all over the condenser, every 2 or 3 minutes for 20 minutes. Then rinsed for 15 minutes. I let it dry for about 45 minutes (so the water wouldn't provide a false cooling) and then went for a 20-minute drive. I'd have to say I wasn't impressed. It's a typical hot day here, but I got nothing but cool air.

I'm thinking of leaking a little pressure off through the low-side port. I think dr_bowtie said R134 works better at low pressures.

Does this sound good or am I too the point of replacing the compressor already?

Thanks!
Bryan