A/C System - maybe I can help

[Crin]

Hi All,

I just replaced the entire A/C system on my 1972 SDV and converted it to R-134a.  I have come to know the system inside and out (at least for the components under the hood) and would like to offer my assistance to anyone who might be experiencing any problems.

Here to help,
Crin

[Denise 20352]

  How well did that work?  After being ripped off by an air conditioner shop, I redid my 76 CC last year.  As I recall, it cooled really well, but this year Ive noticed that the cooling isnt as good at idle as it should be.  A fan modification helped, but I still think that it could do better.  Maybe I need to check the pressures.  It could have a slow leak somewhere.

  I was just wondering how well it worked out on the 72.  Does it have a VIR like the 76, or some other type of expansion valve? Ive done a few other cars and they all worked really well, especially our 92 truck.  The newer Cadillacs (newer than 76) with the acc/drier seem to take to the conversion.

-denise

[Crin]

Hi,
It worked surprisingly well.  The temperature coming out of the vents gets as low as 45 degrees although I would say that the average is 50 deg.  Its quite cold as Ive had to turn the temp dial to 75 to keep it from freezing me out.  That was a first.

The expansion valve that you mentioned is not the same as on my 72.  This is the classical expansion valve that sits just outside the evaporator.

The modifications Ive made were to buy a POA valve from old air products that was tailored to R-134.  This allows refrigerant to flow through the evaporator at lower pressures than the stock valve which would prevent the flow at 29 psi.  This one allows it up to 22 psi.  The new POA valve and the electric fan I think are the two big factors that helped out a lot.

-Crin

[Jerry CLC # 14369]

Greetings,

I continue to experience A/C problems even after having the system serviced (1970 CDV).

I have narrowed it down to the expansion valve or the suction throttling valve. In either case will the system have to be completely recharged if I break a line ??  (4 lbs of freon @
$65.00 per. lb.)

[Denise]

  Yes, unless you can come up with some way to quickly cap it before the refrigerant runs out, without getting frostbite, inhaling the stuff, or getting it in your eyes.  Its gas everywhere in the system when static, so an opening anywhere in the system causes it all to go.

  In addition, you should evacuate it before recharging.  I dont always do it, if I can get it capped right away, but I live in the desert.  If the system is left open long enough for air and moisture to get in then youll also have to replace the drier, so cap it as quickly as you can.

  Also, if you have any greenie weenies in your neighborhood, dont let them see you letting the refrigerant out.

-densie

[Crin]

Hi,
I agree with Denise but in addition I would like to offer the following suggestion.  If you narrowed the trouble down to the expansion valve and the suction throttling valve (more commonly known as the POA valve) then I would break a line open and let the R-12 out then replace the expansion valve (I got mine from Advance Auto Parts for about $35) and update the POA valve to one thats better suited for R-134a refrigerant.  I got mine from http://www.oldairproducts.com TARGET=_blank>www.oldairproducts.com for about $100.  In addition you will have to replace the acumulator which sits next to the condenser.  You can now recharge your system with R-134a which is considerably cheaper.

It is important to update the POA valve because the original valve is designed to work with R-12 pressures (the original shuts off the flow of refrigerant to the evaporator at 29.5 psi).  R-134a operates at lower pressures and the new POA valve allows the operating pressure to drop to 22 psi before shutting the flow off to the evaporator.

I replaced the compressor, the POA valve, the accumulator, the expansion valve, had the evaporator and condenser boiled and added an electric fan to the front of the condenser and I have to tell you that it is cold in the car even on hot and humid days.

I did most of the work myself (other than the boiling of the two components I mentioned) and spent just under $500.  I think it was well worth it.

Hope this helped and sorry for being long winded.
-Crin

[Crin]

I forgot one thing ...

When recharging with R-134a it is important to charge the system to 85percent of the total R-12 capacity (the 4 lbs).  I used 4, 12 oz cans of R-134a and its working really well for me.

Cheers!

[Densie]

  I sent a contact to old air products to ask about the VIR elimination kit that I found in their catalog, and whether they had a VIR that was optomized for R134.  The A/C shop that replaced mine would probably have not had a clue.  They didnt even put the right compressor or oil in.

  Also, I will remove the transmission cooler that I have installed.  I think that it is bigger than I need, and maybe restricting the airflow over the condensor.

  And then I was reminded that there is a sight glass in the VIR, which Ill have to check.  Its still 102 degrees here and I definitely need to get it working right.  Well see how it goes.

-denise

[Denise 20352]

  I removed my large transmission cooler, and a pusher fan that was probably too small.  With the proper airflow over the condensor, it cools much better.  I was getting a brain freeze and I had to turn the vents away from my face.  Its still not as cool at idle as a brand new car would be, but it does every bit as well in cruise.  Considering that the system was never made to use R134, I think that the conversion was very successful.

-denise

[Bruce Reynolds # 18992]

Good for you Densie,

It surprises a lot of people when they find that simple thing as a transmission cooler interferes with the flow of air.

Helps the longer life of the transmission, but sacrifices the cooling ability of the A/C and Cooling system.

Bruce,
The Tassie Devil(le),
60 CDV

[Denise]

  Ive heard that synthetic transmission fluid prolongs the life of the transmission, so maybe thats a better idea that wouldnt interfere with the air conditioning.  There isnt anything wrong with my transmission, I just want to keep it that way.

-denise