A/C 134a conversions Blue-Tube

[boomdriver]

A few weeks ago there was a thread about a/c and engine heating. I had heard of this before, but another member suggested that a Ford "blue-tube" orifice tube be installed because it was a little smaller and worked better for converted r-12 systems.

Well,. while doing some research on this and finally going to get one, I discovered other types of orifice tube for Ford products that cross over to GM.
That same line that offers the blue tube for 134a, also makes a red-top for whats called "severe" duty conditions. Systems that see 105* ambient. I was going for one of those, then I see the "smart-tube"....
Thats the self adjusting orifice tube thats designed for r-12 systems that have been converted to 134a. These are supposed to cover all the bases.
Its a variable orifice that operates off of the pressure, and increases cooling at idle by changing size, and again at higher rpm flow to get the max gas/liquid exchange. I did some more reading from different web sites and it seems that this is not witch-craft, and not well known in the auto a/c business either...but everything says that it works with a real 10-15% increase in cooling, and getting cold air faster.
The blue tube cost $1.98....the smart-tube was $21.00. A new condensor is about $50 on Fee-Bay, ($99 locally) so you can do a major a/c upgrade for under $100 if the comp/dryer is in good shape.
$100 for 15% better cooling? and less drag, less pressure....SOLD.



And I walked right past r-134a on sale for $5 a can last week....
oh well.

Do a search for "smart-tube" or smart VOV. This might be the solution to systems that are having trouble performing.

 

[Curious George]

From what I have read on the automotive A/C forums, the variable o-tube is not worth the > $20 plus dollars being charged for this device. Just use a Ford blue o-tube and all the other recommended mods and you will be good.

I have never used a variable o-tube, but if I had one available I would test it, but not for $20 dollars.

CG

 

[boomdriver]

i guess testing one would be the point of this thread.

 

[gmjunkie]

i guess testing one would be the point of this thread.

I've been testing them for about 6-7 years,Have 3 vehicles converted with them!! They work great!!
But if you know and understand Automotive AC,you can almost do as good with a Ford Blue!

 

[boomdriver]

I've been testing them for about 6-7 years,Have 3 vehicles converted with them!! They work great!!
But if you know and understand Automotive AC,you can almost do as good with a Ford Blue!

Got both actually....
since the smart tube was a little longer I did not want to be empty handed in case it did not fit, so I grabbed a blue tube in case. Its not like there is a huge expense to justify....<$2 is cheap for a back up plan.

Thanks for the input, Thats what I was hoping for was to hear from someone that has used smart tubes.

 

[boomdriver]

well, got my new radiator and installed with the new big a/c condender.

Radiator seems to be doing well.
Real test comes with a/c running while sitting in traffic for 2 hours..
Got all My a/c parts today so tomorrow is all about blowing out. some sucking things out too...

then, after all the "NEW" i should be able to hang meat in the cabin.

I will let you all know how well things work. Should be good with the motor generating all this heat, Thanks Junkman for the tips !

 

[Jeb]

I'm about to commit heresy and let folks know how my 87 was changed over from R-12 to 134.

My mechanic purged the system and left it on a vacuum for about 12 hours.

He then charged it with R-134. That's it. No parts changed at all.

I've been running the car every day for 2 years now and it still puts out enough cold that even in a convertible, it stays nice and cool even in hot Louisiana summers, even in traffic. I have also not had to add any R134 in that 2 years.

I'm not saying everyone should do this but it works for me and there's nothing special about my L-98. Strictly stock, even to the thermostat.

 

[boomdriver]

My mechanic purged the system and left it on a vacuum for about 12 hours.
QUOTE]


12 hrs ???????????

he could'a sucked all the hot air out of Washington DC in that time !

 

[93Rubie]

Let us know what your duct temps are. I did a recent conversion on a 91 Nissan Truck and we had 45 degree temps out of the ducts sitting in the shop on a high 80's day with lots of humidity. With only the mechanical fan providing any airflow over the condenser. Not too bad.

 

[boomdriver]

Let us know what your duct temps are. I did a recent conversion on a 91 Nissan Truck and we had 45 degree temps out of the ducts sitting in the shop on a high 80's day with lots of humidity. With only the mechanical fan providing any airflow over the condenser. Not too bad.

I will....just ran the a/c today and now have new questions to get answered...
The larger condensor should require MORE 134a gas if it is bigger, right?
the est was 2.75 lb of r-12, so about 2.2 of 134a in a stock size system. I am trying to find out just how much bigger this condensor is compared to the stock unit. I put in the 2.2 and cooling is poor, but its there.

I'll get it figured out this weekend and have a freezer for a cabin,. I THINK that I need more gas, just don't know how far to take the low pressure with extra gas in a larger system.:W

 

[GRAND SPORT #12]

BOOMDRIVER i assume you have manifold gauges it will be a big help on 134 i see the pressure is just a hair lower than 12r. low side shoud be 30 to 40 high side in the 200 240 range now higher heat will increase these pressures so i you add freon just monitor those pressures if you are in the 35 on the low side and high side not lol going crazy you should be optimum on freon level

 

[Curious George]

I will....just ran the a/c today and now have new questions to get answered...
The larger condensor should require MORE 134a gas if it is bigger, right?
the est was 2.75 lb of r-12, so about 2.2 of 134a in a stock size system. I am trying to find out just how much bigger this condensor is compared to the stock unit. I put in the 2.2 and cooling is poor, but its there.

I'll get it figured out this weekend and have a freezer for a cabin,. I THINK that I need more gas, just don't know how far to take the low pressure with extra gas in a larger system.:W

The best way to add refrigerant is by weight (use a scale for 15 or 30 lb tanks). If you are using 12 oz. cans, you can weigh those as well and / or add up the cans (and partially used cans).

I would fill the system with the recommended refrigerant level called for by the old condenser, then add 1 or 2 oz increments until the vent temps start dropping to about 40 ~ 42*F with the system on recirculate and med fan speed. (run system for 5 minutes or so between charges to let it stabilize)

Is your low pressure cut-out adjusted for R-134A? With the fan speed on low, the compressor should cycle about 20~21psi (or 3lbs less than what the R-12 was set for)

CG

 

[JohnGrawcock]

My mechanic purged the system and left it on a vacuum for about 12 hours.
QUOTE]


12 hrs ???????????

he could'a sucked all the hot air out of Washington DC in that time !

You'll never suck the hot air out of DC faster than those a$$ holes can spew it.

 

[jonszr1]

how true .plus bullsh*t creates alot of methane gas

 

[G Winter]

I will....just ran the a/c today and now have new questions to get answered...
The larger condensor should require MORE 134a gas if it is bigger, right?
the est was 2.75 lb of r-12, so about 2.2 of 134a in a stock size system. I am trying to find out just how much bigger this condensor is compared to the stock unit. I put in the 2.2 and cooling is poor, but its there.

I'll get it figured out this weekend and have a freezer for a cabin,. I THINK that I need more gas, just don't know how far to take the low pressure with extra gas in a larger system.:W

compared to R12 80% 134A is used. Depending on temps the low side pressure on 134A is form 34 to 50 lbs 45 usually seems to be about right at 80 deg. High side pressures on 134A are scary high when you have been used to working with the R12.I also pay attention to the amount of condensation on the return side of the evaporator, which does vary with diff humidity .

Glenn

 

[boomdriver]

compared to R12 80% 134A is used. Depending on temps the low side pressure on 134A is form 34 to 50 lbs 45 usually seems to be about right at 80 deg. High side pressures on 134A are scary high when you have been used to working with the R12.I also pay attention to the amount of condensation on the return side of the evaporator, which does vary with diff humidity .

Glenn

Yes, thats I was using as a guide, the pressures. Since the new condenser has more volume, the amount of gas may have changed but the pressure values never will.

Thats also how and why I've reached a conclusion...my compressor is bad.

The system should take around 38-40oz of 134a to get in the 45-50lbs low pressure range when ambient temps are 85-90 degrees.

Whats happening is a low pressure of 120+lbs at rest with only 24 ozs added, and at start up low only pulls down to 60-65. So I don;t add anymore. The low does not seem to pull down anymore with rpm increase either.

The compressor does make some noise, a mild rattle as gas charge builds. The more gas the more the rattle. Not loud, but its there. Noticable with some vibration.

The "feel" test is good initially but the evap inlet quickly warms. Thats very close to exhaust header, so its hard to tell. I am going to insulate that inlet so exhaust heat does not effect it.
The outlet stays cool as does the accumalator can. The accum can sweats quite a lot. So do I in this 90% humidity. Its worse than the swamps of Lousiana/Mississippi.

It appears that the compressor is not moving the refridgerant as it should. The low should be way down there with only 2 cans (24oz).
The orifice is not plugged, pulled that apart 3 times because symptoms indicate a plugged tube, but its not.
Only thing left is the compressor. Every other piece of the system has been blown out, or new, and been flushed and blown out. Its sterile with crystal clear new PAG oil of the right viscosity.

Thank God for warrantys...the replacement compressor is covered so its just labor to me.

 

[G Winter]

Based on your last description of the system operation , I have to agree with you. A restriction anywhere in the system would raise your high pressure and lower the low. Is your coolant level where it belongs? I have seen low coolant do strange things to the air conditioning.

Glenn

 

[boomdriver]

Based on your last description of the system operation , I have to agree with you. A restriction anywhere in the system would raise your high pressure and lower the low. Is your coolant level where it belongs? I have seen low coolant do strange things to the air conditioning.

Glenn

yeah, i explored that but its not the issue. Brand new HD all aluminum double row radiator that instantly dropped the engine temp 25 degrees...even in this misery of a summer. The radiator and condensor were installed together.

After LOTS of reading and speaking to some a/c guys, the compressor has to be weak otherwise it should pull a half charge way under the normal PSI low side. With only 24 oz its idling at 60-65 psi. Thats twice what it should be..:confused
There is some cool air thru the vents, just not enough to do any good. Oh well....I pressure washed and cleaned today so I can swap compressors in the next couple days and get this darn thing RIGHT before the end of summer. I'd like to sit in traffic at least a few days this year and not "sweat it"...

The new engine temps are certainly nice....stable and low enough to perform, high enough to run as designed. From 235 down to 205....I'm very pleased.

Old POS brass stock style radiator for sale. Good for boats up to 19' with nylon rope...(boat anchor about all its good for IMHO):L

 

[G Winter]

Old POS brass stock style radiator for sale. Good for boats up to 19' with nylon rope...(boat anchor about all its good for IMHO):L

And is actually better than most stock radiators.

Glenn

 

[boomdriver]

And is actually better than most stock radiators.

Glenn

it really is !
I've run that brass for 10 yrs.....had no issues outside of heating in extreme conditions. Even like that, its still an upgrade over the plastics...

Anyone in Tex area, make me an offer...and the brass is yours..!