ac system wont blow cold. or even cool.

o i have built a system for my 64 el camino.

parts: 66 vintage mark iv monitor underdash unit new expansion valve r134 barrier hoses, all o-ring fittings except the two flare fittings for the underdash unit new parallel flow condenser, as big as the radiator new drier vintage air manifold for Harrison r-4 compressor used 89 vintage Harrison r-4 compressor, complete with the rest of the serpentine accessories (from extended cab fullsize truck)

the system was built by me, and initially charged with PAG oil and r134a straight out of the can. no vacuum applied. I never got the pressures up to where the gauge on the can dispenser said it should be, but the system was blowing about 10 degrees below ambient temperature inside the cab.

I then took it to a local shop for a line flush, proper oil, vacuuming, and correct r134 charge. it reads within spec on the gauges according to the shop, but blows ambient temp. the low side fitting coming out of the evaporator is cool to the touch, but not very. no condensation being formed. this is regardless of engine or vehicle speed, so I doubt its airflow related.

engine has a mechanical clutch fan.

what are my options here? did I miss something in system design? did they miss something with system pressures? anything I can do to make it work better? am I expecting too much?

thanks guys. usually I install aftermarket streetrod kits and sanded compressors, but wanted to do something different (and cheaper) this time. hoping im not going to regret this.

Bueller?

What are the pressures on the high and low side before and after the compressor clutch kicks in? How long does the clutch stay engaged before cycling off with the system turned on?

You're probably going to want your own set of gauges for this exercise.

Compressor never kicks off.

And I don't own gauges yet. Will the harbour freight suffice?

In reply to Dusterbd13:

Compressor not turning off isn't a good sign. Harbor Freight gauges are probably fine. Last set I bought didn't come with a third hose so I can't add refrigerant as it stands, you may want to check on the set you get; I can buy a third hose if/when the time comes (and my car's A/C isn't very cold so it may be soon).

Also, how long did the shop put the system under vac? Shops I've worked in wanted a car overnight for something like this, to pull a constant vacuum to find if there's a leak or not. The compressor not turning off is either a high side pressure switch not changing state, or the pressure switch that's supposed to see pressures high enough to change state isn't actually experiencing a pressure great enough to cause it to flip.

EDIT: It's got to be the high side switch not seeing enough pressure, which makes me wonder what your gauge readings really are. At least there's not a problem with the low side cut-out switch, assuming the system has one.

To truly dry out the system you need to vac then back flush with dry gas (n2 normaly) then vac again 4-5 times as water vapor can freeze under a high vacuum. sounds like to me your compressor is NFG or they added way to much oil.

You really need a set of manifold gauges here. Something is severely out of whack, you should have snow out the vents with the setup properly charged.

You didn't do something stupid like forget to install the orifice tube, right?

The clutch fan may not be providing enough air flow through the condenser. Just another thing to check along with everything others have mentioned.

In reply to iceracer:

I would think insufficient airflow would only lead to poor low speed performance and the system would still freeze you out on the highway.

No orifice tube in this system. Uses an expansion valve instead.

Shop that did the vacuum and charge offered to try to make it right. So it goes back Monday. If they are unsuccessful again, I will purchase gauges and we will attack it with your help.

In reply to Dusterbd13:

Ok, could still be a problem there. Either in the part itself or installation (the TVX sensor bulb has to be in contact with the suction line). Pretty easy to see on a manifold gauge set though (high low side pressure). I suppose it's possible it worked at the shop and then failed.

Glad it's going back to the shop because there's no point discussing this any further with so little information. I mean, we're speculating on pressure switches that may or may not exist and postulating problems that would cause obvious pressure reading symptoms on a set of gauges.

So basically, without a set of gauges, noone here can tell you anything, regardless of the fact that they're trying anyway.

I bought a set of HF gauges for like $39. The high side fitting didnt fit most of the service ports i tried it on. I ended up buying a quality high side fitting for the hose for another $35. I could have spent $75 (or less?) on something that worked the first time. Now the set is like 5 years old and the hoses are falling apart and one of the valve knobs cracked in half and fell off. I'm normally a big proponent of HF stuff in the right cases, and maybe the product has improved since then, but my experience with HF gauges has definitely been subpar and i wouldn't buy them again unless someone told me they've majorly improved.