134a..... b*

[454Man]

Just went against my thoughts and filled my ac system with it:-( I've gotten better results with r12 and 12a then 134a. I say don't do it. It cools a little but not much... ahhh in texas I wouldn't do 134 105+ days with a little cool may be better than nothin but.... NO.

[Avidyn]

How did you go about filling it? Did you change compressor oil and seals? New oriface tube, etc? If you converted, you can't just pump it in and expect it to work.

[bd]

Avidyn is right.  The refrigerant is part of a calibrated system.  Converting to 134a requires hardware changes for optimum results.

When I converted my 87 to 134a, following a thorough flush, I used the original R4 compressor, a new serpentine style condenser, 134a orifice tube and recalibrated low-pressure (cycling) switch, then added a high-pressure switch, relay and factory 12" auxiliary condenser fan; installed a new accumulator, all new o-rings, added a conservative amount of 134a compatible oil, evacuated, leak checked, and charged it.  It blows painfully cold air (33* @ nozzles) with no evaporator freeze over.  Works better than any factory GM A/C system out there.  Eventually, I upgraded to a later model, high-volume blower motor.  Now, even on humid, 110* days in California's San Joaquin Valley, it's nice and coooool.  So cool, in fact, that I typically run the temp control at ~75%, low-to-medium fan.

[cvbear]

BD, where did you get the condenser fan?  Did it come from the dealer?

[454Man]

Well guys I will start by saying I am universal certified tech. I changed the compressor+ oil, all orings, drier, orifice tube, vac the system down. Didn't flush( maybe I should have) because the system was closed. Air coming out the vents like 53°. Bet theres some noncondensables in the system that a flush would remove

[454Man]

Avidyn is right.  The refrigerant is part of a calibrated system.  Converting to 134a requires hardware changes for optimum results.

When I converted my 87 to 134a, following a thorough flush, I used the original R4 compressor, a new serpentine style condenser, 134a orifice tube and recalibrated low-pressure (cycling) switch, then added a high-pressure switch, relay and factory 12" auxiliary condenser fan; installed a new accumulator, all new o-rings, added a conservative amount of 134a compatible oil, evacuated, leak checked, and charged it.  It blows painfully cold air (33* @ nozzles) with no evaporator freeze over.  Works better than any factory GM A/C system out there.  Eventually, I upgraded to a later model, high-volume blower motor.  Now, even on humid, 110* days in California's San Joaquin Valley, it's nice and coooool.  So cool, in fact, that I typically run the temp control at ~75%, low-to-medium fan.

Where did you get this high volume blower motor you speak of?

[zieg85]

I routinely get 38 degree air out of my Ford Escape.  When my 85 was all charged up you could hang meat in the cab and it was converted to 134.  Do you have a good seal on the door that closes?  You could always bypass the heater core temporarily to see if that helps.

[bd]

BD, where did you get the condenser fan?  Did it come from the dealer?

GM P/N's:
15547033  fan
15547034  motor
15547032  mounting bracket
14089936  relay (Delco 15-8240)
2724064    high-pressure switch (Delco 15-2150)

If the fan & motor are obsolete, you may be able to substitute:
http://www.csr-performance.com/shop/product.da/csr1212hd-12-inch-heavy-duty-reversible-electric-cooling-fan

Where did you get this high volume blower motor you speak of?

Napa P/N:  655-1744  blower and cage out of a 1994 C1500 with A/C - for a little better flow

Well guys I will start by saying I am universal certified tech. I changed the compressor+ oil, all orings, drier, orifice tube, vac the system down. Didn't flush( maybe I should have) because the system was closed. Air coming out the vents like 53°. Bet theres some noncondensables in the system that a flush would remove

Flushing is important, but I think my Ace was the aftermarket serpentine condenser I used.  The auxiliary fan is important at idle.  GM factory A/C performance on our trucks in California is rarely better than ~53°.

...When my 85 was all charged up you could hang meat in the cab and it was converted to 134.  Do you have a good seal on the door that closes?...

X2  -  Check the blend door adj/function in the evaporator/heater housing under the dash. 
In that hot Texas weather, good cab insulation helps, too.   

[454Man]

Will check the blend door guys thanks!

[454Man]

Ok guys check the blend door and it functions.looked up under the his and figured why not put some insulation around the suction line, drier, and highside where the orifice tube is. well that changed everything. I now get that meat locker everyone is talking about:-) I also blocked off the floor vent for more flow out of the upper 4 vents...now it really blows! Guess to much great was soaking into the lowside hose driving up the highside pressure. which makes sense because in the heart of the day the ac was not all that great.
Next tinted windows to keep the sun off my back:-)

[markus]

alternative to think about, probably illegal:

i filled my two cars (91 pickup and 92 grand marquis) with mp39 (r401a). blows ice cold (didn't measure temp though) and no additional work involved, just top off the r12 (or replace completely, works well with most mineral oils). only difference is that it has to be filled in as liquid (can's bottom up). high side pressure +20psi, low side same as r12. filling amount 75%-90% r12. data sheet says cooling potential is about +10% compared to r12.

you get that stuff at a/c service stations (the stationary ones).

other method i read about: top off the r12 with r134a, up to 50/50. can't remember where i read it, but the argumentation more or less was like that: r12 is taking care of the oil circulation (where r134a would fail) and the blend you get works ways better than r134a alone, even better than r12 alone. obviously with this method it's a matter of time to get a compressor failure...