Auto A/C Question

[ehenry]

I've completely over hauled the A/C system in my 86 Toyota truck. I've replace everything from the condensor back.....condensor, receiver filter, compressor, evaporator core, expansion valve, pressure switch, replaced every o-ring...Everything ! I put 8 ounces of pag-48 oil in the compressor and charged the unit with 134a freon. Both low and high pressure readings are with in spec according to my shop manual for the truck which are 28/30 on the low side and 275/300 on the high side. The coldest the air will get coming out of the dash vent is 40 degrees. With the old R-12 in the system it would blow 32 degree air. In my car, wifes truck, and sons which are late model 134a factory systems the air gets colder than my little truck......anyone got any ideas or is this the best yall figure i'm going to get.

 

[aspeck]

Re: Auto A/C Question

40 degree air is pretty dang good for an A/C. I would be happy with that. In my car, the temp coming out the vents is the same as what goes in! (Oh, guess it helps if you HAVE A/C)!. Wifes car blows about 46 degrees most times. It has some wierd intermittent problem that I have not been able to find for the last 3 years, though, so sometimes, for a few minutes, it blows quite warm air. My Denali blows cold air at 48 degrees.

 

[rottenray6402]

Re: Auto A/C Question

40 degrees isn't bad. If it blows to cold the system gets iced up and then doesn't blow cold at all.

 

[jimr]

Re: Auto A/C Question

as a rule of thumb if your pressures are within spec and you can get 30-40* cooler than ambient air temp you are doing good. also unless you converted everything on you truck to 134a (condensor,evap hoses and compressor) it won't be as cold as the old r-12 system was. also if you used r-12 stuff with r-134A (retro-fit) you don't add as much to it if it took 2.5 lbs of r-12 you add 2 lbs of r134A.

 

[ehenry]

Re: Auto A/C Question

The hoses were both recently replaced prior to this over haul. I flushed them out really well and reused them.

 

[SS MAYFLOAT]

Re: Auto A/C Question

You did pull a vacuum on it before charging it? If any air with moisture gets into the system, the moisture will freeze in the orifice stopping the flow. R-134a is bad for absorbing moisture. Pulling or evacuating the system first gets rid of the air and moisture. Hope this wasn't bad news for ya.

I know some guys that will purge the system using refrigerant to blow out the air, but sometimes that just isn't good enough to get the moisture out. Air in the system will also give you more head pressure on the high side also. Not good on the compressor or your mileage.

 

[ehenry]

Re: Auto A/C Question

Durn tootin, I pulled a vacume on it. As a matter of fact I put the machine on it and left for about 3 hours while I did other things, turned it off and let it sit over night with my gauges on it to check leaks....vacume held up strong. I charged it the next morning.

My son's "03 Chevy truck will blow almost 30 degree air in the middle of the day when it hottest out. My wifes 99 doge will blow almost 35 degree air. I'm just trying to yall's oppinion.

 

[rickdb1boat]

Re: Auto A/C Question

It's like any other cooling systems. Some work better than others. And if it was me, I'd have pulled the vacuum all night to make sure I got rid of all the moisture in the lines and system. A lot of people are under the impression that a vacuum only removes air. Not true. Pulling a deep enough vacuum for long periods will also remove moisture hidden deep in the system. Especially important for those open for any periods of time during warm humid weather...Run it for awhile and if no improvement, replace the receiver drier and pull a deep vacuum again...

 

[jimr]

Re: Auto A/C Question

A R-12 system retrofitted to R-134A will never cool as good as the r-12 did or a r-134a system. the orifices in the condensor and evaporator are different sized.

 

[LubeDude]

Re: Auto A/C Question

A R-12 system retrofitted to R-134A will never cool as good as the r-12 did or a r-134a system. the orifices in the condensor and evaporator are different sized.

Absolutly, you are doing good with what you have.

I needed air for a vacation about 5 years ago on my 87 RX/7. It hadn`t worked for about two years before that and it was an old R12 system. I went to a wrecking yard and got a used compressor, put it on, didn`t evacuate or change anything. Put R13 retrofit kit on it and charged it up. I only wanted it to work for the trip. It still works to this day. I`m one of the lucky ones though!