A/C problems

[anniegreensprings]

I have a 1992 Coupe. i replaced the compressor, receiver dryer and condenser. it's been retrofitted for R134A i had the system vacuumed and checked for leaks, and was good to be re-charged. the problem i'm having is that when i make the system call for A/C cooling, say 22 degrees celcius, it blows a little cool air but not like it use to. some times it well blow a little warm air for a few seconds and then a little cool air.
this does it when you run it on the manual way and even when you run it on auto. when you turn it down really low and run the system on recirculate it gets quite cool for a bit but then it starts to blow a little bit warmer. when you call for cool air, shouldn't the clutch on the compressor cut in and stay engaged. i think it's in one of the switches , but i'm not sure if it's in the cycling one or refridgerant pressure sensor switch or compessor engine coolant temperature switch. now i am running a 160 thermostat. stock is a 180. could this be creating the problem. if anyone, who has a good background in A/C systems could help me out i'll leave them a little somthing in my will.
just point me in the right direction, thank you for your time.

 

[G Winter]

I am no expert but your problem makes me think it doesn't have the proper charge. The 134 A is very particular on the amount of charge. When it was converted was the orifice changed. A self adjusting or a Ford orifice makes the conversion work much better.


Glenn

 

[boomdriver]

Yup...
Glenn is absolutely right.
I did a complete a/c overhaul last summer and found that there are a couple things that are different in these conversions...

134a is slower to produce cold air in GM systems. My buddys *ord truck blows cold the instant that its turned on. Likely because the system was designed for efficient use of 134a while or Vettes are either converted or they just do not have the condensor area and evap area to be as efficient as they could be.

134a has different pressures than r-12 so the amount has to be altered...The r-12 used 2.2 lbs.....to get proper 134a pressures you can only install 2 lbs.

The orifice is different, but the pressures in 134a have different needs at different temps, so the variable or self adjusting orifice seems to help.
Mine got a new........everything and it was charged with gauges and evacuated. At start up it takes a couple minutes to feel the cool air, and after 5 minutes its cold.It stays cold even when idling in traffic after that. 134a just has different characteristics than the r-12 that worked so very well.
BTW, Thats in 95* ambient with 80% humidity. A pleasant Tx afternoon....seriously ! it gets worse.:ugh

I also installed a new condensor that had more surface for heat exchange, that was only $75.

ask for a Ford "blue tube" orifice or a GM smart tube. Ford tube is $4 while the smart tube is $20.

 

[gmjunkie]

I agree with Boom and Glenn,Except.............
No need to change condenser!!
Ford Blue tube
Raise the low side pressure cut off switch to 21 lb's for 134a from 16-18 for R-12!(It should be adjustable!! Look under the plug,RT Up,Lt Down.1/8 turn approx 2 lb psi !)
Be sure to purge the gauges/hoses and Weigh the refrigerant in with a EXACT 2 lb charge,1 oz over or 1 oz under your cooling will be slow and can also freeze up the evaporator under some weather conditions!~!!!

 

[Curious George]

I concur with everything said so far...

If your low pressure cut-out switch is not adjustable, you can buy one preset for R-134A.

I converted my '92 and it has been working great for 3+ years now!

CG