FACTORY A/C: How cold should it be?

Texas Tom

Texas Tom

Senior Member
I'm pondering the purchase of a 1967 Mustang that's equipped with factory a/c. This week the system was converted to use 134a refrigerant.

The center air registers show a 55-degree reading (ambient outside temperature is about 90 degrees).

My modern vehicles' a/c systems produce a 40-degree reading at the registers.

I understand that the "VINTAGE" brand a/c system produces a temperature at the air register of about 40-42 degrees.

QUESTION: Does it seem that the factory-installed A/C system in the '67 Mustang is performing correctly? Or should the temperature at the air registers be about 10 degrees colder?

The a/c shop that did the conversion has suggested that factory-installed a/c systems in the mid-1960s weren't nearly as efficient as today's systems. That may be true, but my friend has a '55 Buick with factory air and you can hang meat inside the car all summer long.

Thanks.
 
I used to do R134 conversions on R12 cars. The people were never happy. It just doesnt get cold enough using the old r12 parts.
134A expands at different rates and temps as R12, and operates at different pressures as R12.
So if your car says 2 lbs of R12, and you put 2lbs of 134, it wont work right. Its going to be less 134 than R12.. You almost have to add it as the car is running, and it will never get cold enough if the car is running in one place and very hot. It has to be moving, and at about 1500 rpm's.

Maybe let some out..off the top of my head, I dont remember the pressures it should be for 134..

I'll go look at my gauges and see what it says.

But hey..55 is better than 90!!!
 
I retro'd an '89 Toyota pickup to R134 and I couldn't tell the difference. My Vintage Air designed for 134 has 38 degree air at the vent after it has run a while.

I don't think 55 degree air at the vent will cool the car in Texas weather.
 
I just put Air in my 56 Crown Victoria and have not had it charged as yet.It calls for R12 but where in the heck will find it???? I took the front seat out of it so I could work under the dash and install electric wipers also.That all done now. My wife is short so I half to raise the front seat so she can see over the steering wheel.It all going very well but slow.I hope when I have it charged it cools as it should.:D
 
It's hard to tell the charge on a 134 conversion by looking at the sight glass, with R12 it was full when it was clear, on 134 conversions 80% by weight of what the R12 weight usually works, the low pressure switch should be replaced by a switch that also shuts off for too high pressure, too much paint on the condensor will reduce it's heat transfer, adding a fan in front can help, getting the most airflow helps --fan shroud,sealing the edges to insure all the air getting sucked by the fan is also going through the condenser, if the condenser was borderline in size new it will be too small for 134( to have max cooling), too much oil can reduce efficancy ( I suspect you have the york comp, when the systen was empty during the conversion they should have checked and corrected the oil level by removing a plug and using a dipstick, also a dye should be added to find any leaks later.
take a look at the fins on your condenser( in front of radiator) if dirty --clean
add on air does not usually work as good as factory air
 
Back in the early 60's we said if you could get 30 to 40 dg under the outside temp it was good. My shop has converted a lot of newer A/C to 134. Most work good. I have not converted a old style Ford comp yet. We use Freeze 12 in them. It is a LOT cheaper than Freon 12, but you do need a license to buy it. of course you don't need a license for 134. I also have used ( Freeze 12 ) in My 70 Merc Cougar and some airplanes with the old style Ford comp. A place called Glacier Gold says they have a replacement that you don't need a license for. Not sure what the cost but I think it would be cheeper than Freon 12
 
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