Automotive Air Conditioning Information Forum

I have a 1971 Pontiac Grand Safari, (b-body). Several years ago I had to have a new AC hose made. The one that goes from the back of the compressor to the condenser. This is the high side. I just noticed that this hose is the same diameter as the one from the evaporator to the compressor, which is the low side. I think this means that my hose was made too big (too large in diameter) and I'm just now noticing.


What issues would this potentially cause? The car hasn't been driven in several years so the new hose hasn't been tested.

Look at the size of the tubes on the fitting(s) and compare. Depending how the hoses were made and when, you could have a mix of standard barrier (larger outside diameter) and reduced barrier (smaller OD) hoses - the diameter of the pipes on the fittings (and thus the inside diameter of the hoses) will be the same for either hose for the same size fitting (say a #8 which would be typical for compressor-to-condenser) but the hoses could be different outside diameters. So a #6 Standard could look like a #8 Reduced - coincidentally those two even use the same crimper size)

There would be no issues. Too big a diameter is OK, too small is not.
If the AC is blowing cold, then forget about it

tbirdtbird wrote: ↑Fri Oct 13, 2023 10:43 am There would be no issues. Too big a diameter is OK, too small is not.
If the AC is blowing cold, then forget about it

I wonder what the logic is behind varying hose sizes. One would think it might be cheaper/easier to make them all the same size.

The thermodynamics of refrigerants dictates the sizes.

The three line sizes in the average system reflect the density and velocity of the refrigerant.

The Suction line to the compressor is generally carrying cool gas. Usually a -10 line. Some systems use a -12 suction line. I have seen -8 suction lines on some small imports.

The discharge line runs high pressure, hot gas to condenser inlet. In most cases this is a -8 line. There is no reason that the discharge line could not be a -10 size. The hot gas would still get to the condenser. In fact, -8 threaded fittings for -10 hose are pretty common.

The Liquid line is just that. Refrigerant LIQUID from the condenser to the expansion device. It requires a lot less volume than the gas. A larger liquid line would use a lot of extra refrigerant.

So it is possible that your suction line is the same hose size as the discharge. As Andrew already pointed out, there are several hose types, with different Outside diameters. We are discussing the INSIDE diameter of hoses.