rick442

1971 442, 455 auto, factory air.
I just bought the new hoses from Old Air.
I will buy a new drier.
My compressor spins freely and sucks and blows.
System parts are at least 17 years old. A/C has not been operational for approx 5 years.
Questions: (Just trying to save a little money but don't want to penny pinch my way to a headache either.)
Should I buy a new expansion valve? How reliable are these?
Should I buy a new POA valve? 134 was in the system when operational. How reliable are these?
Any other advice?
thanks!

toymobile

POA valve are somewhat reliable (sometimes they need a JAR from a SMALL hammer to free up the moving parts) for the price of expansion valve I would replace, Good luck.

Johnny

Koda

It's more of a pain in the rear than a dollar cost to do that. If you are there already, go ahead.

I run a R-12 system with R-134A fittings and oil and R-134A refrigerant in a Chevrolet of those years. I can get a 30 degree drop from ambient temp on max recirc, which is acceptable but not good. I am going back to R-12 some day.

rick442

Thanks guys!

Fun71

Here in Phoenix during the middle of summer that would give you 85º vent temps!

Don R.

My 63 Starfire was converted to R134A seven years ago. The only things that were done were: flush the system, new oil, fittings and receiver drier, leak check, evacuate and recharge. All other parts are original factory. It still works today (fingers crossed) with no additional work and does a pretty good job in Texas heat.

droldsmorland

Retrofitting to R134A.
With R12 production halted it is not a question of if but when your old AC system will have to be converted to the new R134A refrigerant. Besides, you cannot legally purchase R12 without a special license so if you want to do your own AC work, you have to get R134A.
There is a lot of talk of R134A retrofitted systems not cooling well, but if the conversion is done right there is no noticeable loss in cooling capacity. Actually, after I did my conversion and especially after doing the POA valve adjustment described below, I reach 43F vent temperatures on a 90 degree day. The service manual lists 49F-52F as normal, so I'm outperforming the original R12 system with my retrofit!

The process of converting to R134A is not terribly complicated, but there are a few things to keep in mind:

Hoses. R134A consists of smaller molecules than R12. This means it will leak easier. Hoses should preferably be of the barrier type. However, it has shown that older hoses perform ok after they have been used with R12. The R12 impregnates the rubber and acts as a barrier for the R134A. Inspect the hoses. If they are dry rotted now is the time to replace. They are a half-century old...Several of the old car AC specialists can reuse/crimp/weld the original factory ends on to new hoses if that's a concern.

Oil. R12 systems use 500 viscosity mineral oil. R134A systems use PAG oil. The two are not compatible. If mineral oil is used with R134A, it will not mix with the refrigerant, and the compressor will starve for oil and seize. Fortunately, there are solutions. Ester oil is compatible with both PAG and mineral oil. Furthermore, there are additives available that will make the old mineral oil in the system mix with R134A.

Fittings. R134A uses new fittings of the quick-connect type. Fitting adapters are available that will screw onto the old R12 fittings.

O-rings. To minimize the chance of leaks, the new blue O-rings should be used. The older black O-rings used with R12 may promote leaks.

Receiver-Drier. The receiver dryer should always be replaced when the system has been opened. Be sure to get a receiver-dryer that is compatible with R134A. Most receiver-dryers available today will be compatible with both R12 and R134A.

POA Valve adjustment. The POA Valve regulates the pressure inside the Evaporator. It is set for R12's optimum pressure of 29.5 PSI. To get maximum efficiency from R134A it has to be adjusted for a lower pressure. Looking into the inlet of the valve (through the fitting where the hose to the Evaporator goes), an adjustment screw with a locknut can be seen. Loosen the locknut and turn the adjustment 1/4 turn counter-clockwise. This adjustment lowered my vent temperatures from 52F to 43F on a 90F day!

If the system has been apart for a long time it needs to be flushed and blown out

Below are the things I got to get the AC in my '71 operational. The system had been open for several years, damaging the expansion and POA valve as well as depositing dirt and sludge in the evaporator and condenser. If your system is in good shape, some of the items below are not necessary.
1... Rebuilt compressor (Autozone $55).
2... Expansion Valve (Autozone $29).
3... Receiver-Dryer, R134A compatible (Autozone $29).
4... POA Valve (NAPA $67).
5... Quest R12 to R134A conversion kit containing oil additive and fittings (Autozone $25).
6... 2 high side adapter fittings. The high side fitting in the kit didn't work and an additional fitting was needed for the POA valve diagnostic fitting (Autozone $5).
7... Blue O-ring assortment (Autozone $5).
8... 2oz Ester oil charge (Autozone $4).
9... 4 12oz cans of R134A (NAPA $4 each).
10... AC insulation used to insulate the Expansion valve probe (NAPA $20).

bw1339

I've had good luck with R152A (keyboard duster). I have a '63 Jeep pick-up with a factory A/C system from a '68 Wagoneer and it works very well with R152A. It is dirt cheap and works very well in old R12 systems.



I'll be redoing the A/C in my '66 Toro this summer and I plan on keeping the POA and charging with R152A. Working on the Confortron side now

cjsdad

While I was installing A/C units in Phoenix one of the biggest improvements we found for cooling with r134a was to replace the older serpentine flow condenser with a newer parallel-flow unit. They typically have smaller tubes and more of them. This helps to transfer the heat out of the refrigerant much faster and therefore cools better. We didn't change the POA valving, but there wasn't a lot of information about how to maximize the 134a conversions back then. For systems that had been open for any length of time, the receiver dryer needs to be replaced and the evaporator cleaned throroughly. A decent A/C shop should be able to rebuild your original hoses with newer barrier hose for a reasonable price or you can buy the hose and connectors and make them yourself. Bead Lock crimpers are available on ebay and Amazon fairly cheap. You wouldn't want to go into business with the off-shore units but for limited use they should do the job well. You may be able to rent/borrow them from Auto Zone, I don't know for sure.

abrasv

Trying to charge the ac on the '69 Cutlass. According to the gauge it has pressure. Added a total of 44oz of 134A which is the correct refrigerant per previous owner. Book says it holds 48oz. It shows frost on the line after the expansion valve and only blows warm air. Compressor turns on and off with the dash switch.
At first it showed NO pressure so I tapped on the expansion valve and also the poa valve seeing if that might loosen up something if it was stuck. Helped with the pressure somewhat (25psi) but no cold air.
Looking for suggestions as to what to do next please.

Sorry- did not mean to hi-jack this posting.

banny

I used to work for Classic Auto Air where I worked on these valves. I have rebuilt(cut open and tig welded back together) over 100 poa valves easily. They are very reliable if they are clean on the inside. Problem is you can't tell to what extent of debris or corrosion there is inside after all these years without cutting it open. There is a screen that cannot be seen. I have never had much luck with the whole tapping on it with a hammer trick. I would suggest to anyone that just wants to do the "1/4 turn" to verify that it does function with a set of gauges. Had guys try to adjust it themselves only to find out the poa was stuck after they installed and charged. The original Frigidaire Exp valves are pretty robust. I go through these also and install them on 99 percent of all my rebuilds. No significant difference in performance over the new aftermarket ones. And they just look and fit so much better. Here is a quick video I made if anyone wants to check it out.
And one other very important part to replace if going with 134a is the condenser. You want to replace the original tube and fin style cond. with a parallel flow design condenser. Classic Auto Air sells bolt-in parallel flow condensers for around $280. If you are going back to r12 no need for this and contrary to what some guys think, r12 is still available. the general public cant buy it new but I see guys selling cans all the time on craigslist and at swap meets. Even seen them sell it on ebay.

banny

one other thing I would highly suggest is to remove the evaporator if its still installed inside the housing on the firewall. Often there is debris on the back side and if so, it will hinder air flow coming from the blower motor. I don't have a video of this issue on a 68-72 abody but believe me, ive had some that were caked with crap on the evap. here are a couple of videos of what it can look like.

droldsmorland

Solid info banny. Thanks for adding this key info! You likely rebuilt my stuff? I had the 68 done about 15 years ago.

Also good to verify the blend door is adjusted properly and sealing well.

tmaleck

^^^^^^^^^^^^^^
What he said. Big difference in my wife's 92 vette. Easy 20 degrees cooler with parallel flow condenser.
Tim

banny

Could be, I was there in '04

droldsmorland

banny, let me ask you this...I havent hooked the system up yet. The dryer you guys replaced the desiccant in still sits on my shelve with the plastic plugs in it. Is it still good? Was rebuilt in 02, 03ish

banny

As long as the plastic plugs are still there and it hasn't been exposed to any moisture you should be good to go.

rick442

All is cool here.
Thanks for all the advice.
I bought new hoses, dryer and expansion valve. Running R134