Can someone point me in the direction of a really good how-to article or a good book on R134a A/C system service and upgrades ??


I have been running a 134a conversion for fifteen-plus years and have never had the ice-cold A/C that others tell of.

In my truck, I am currently seeing 60* at the vents on a humid 90* day.

I just added a can of R134a to the wife's truck and she is getting less than 40*; I have seen that truck hold down to nearly freezing.

I have already done all the common "did you do this" maintenance and tricks such as :

1. Blower, cowl, kick-panels, and heater-core removed and all leaves and trash removed and all areas clean.

2. Evaporator box removed and evaporator exterior cleaned with foaming coil-cleaner.

3. Grille removed, condensor exterior cleaned, and all smashed fins staightened with a fin-comb.

4. Manual shut-off valve in heater-hose.

5. Blower-motor on relays, both HOT and GROUND, such that it is getting full alternator voltage instead of the factory less than 10-volts; it blows like a cyclone.

6. Fan clutch "pinned" as in completely locked solid regardless of temperature.

7. Pressure-switch screw backed out a touch to lower cut-out pressure.

8. Last summer, I had to replace a leaking hose, so I took the opportunity to install a VOV; I got the one for extreme hot climates.

At that time, the system was pullled under vacuum and recharged.



I am not at all impressed with the expensive VOV and was getting cooler air with whatever plain old orifice-tube that was in there.

That being said, I was later informed that I needed a special tool to unlock/remove and install these orifice-tubes; nobody thought to tell me that when everyone was saying to switch the thing; I just eased the old one out with a pliers and pushed the new one down in there.


Just a few days ago, outside temperature a very humid 90*+, engine at a fast idle, A/C on MAX, 60* at the vents, HIGH-side was showing 350 PSI (or whatever it is), LOW side was at 35-PSI; this was after nothing whatsoever beeing done since last summer.

I remembered from last summer having readings more like 28-LOW and 250-HIGH; I don't know where these higher numbers came from.

Please help me get cooler; thanks.

 

When a hose is replaced and a vacuum pulled, does that also remove the oil from the system ??


When refrigerant is lost via a slow leak, is a proportionate amount of oil also lost ??

When one adds the occasional can of refrigerant, should plain refrigerant be used or that that also contains oil ??

Thanks.

 

My truck is a standard-cab with a big semi sleeper-bunk; so, cubic-feet-wise, about equivalent to a 4-door cab or larger.

Which orifice-valve should I be using for maximum cooling ??

Thanks.

 

With a R134a system, what gauge readings should I be seeing on HIGH and LOW sides for optimum cooling ??

Thanks.

 

Good A/C thread A/C Info

-Enjoy
fh : )_~

 

If your high side pressure is running higher, that might be a airflow problem across the condensor in front of the radiator. What type of engine fan are you running, and have you cleaned out the coil in front of the radiator. You should also be running a fan shroud.

 

You will not see these truck A/C's be as efficent on 134 as they were on 12 which is why I have continued to run 12 in all mine. Though it is a little hard to find you can still find 12 and it will perform better in a system that was designed for it.

Low side pressure of 35* should give lower than 60* vent temps. Sounds like you may be re heating the vent temps by introducing heat from the heater core but you stated you have a valve to cut the water flow off. Have you tried misting the condenser with water to see if the pressures drop? This would indicate air flow restrictions to the condenser.

Here is a good post regarding 134 conversions that may help some:

Automotive AC Information Forum - ACKITS.COM