AC Outlet Temps

[femurphy77]

I've been working on the AC in my '92 pretty much all weekend and am not satisfied with the results. I've replaced the orifice tube, vac'ed the system down to 30" for 6 hours and added about 26 ounces of 134. Everything seems to be working but in an outside air temp of 94 degrees, humidity around 60% my center outlet temp on max cooling settings is only 59 Degrees. I am by no means an AC mech but do pretty decent in most of my mechanical endeavors. Low Side pressure is 32# and hi pressure is around 300#. I have plenty more refrigerant but basing the amount on 80% of the r12 charge I should have enough. The car had 134 fittings on it when I got it so I don't know the history of the conversion. Everything seems to work but I'm just not getting sufficient cooling. AM I asking too much? TIA, FM, Indy.

 

[nyernga]

If that 59 degrees is with the car sitting still then I'd say you're asking too much. Try taking the temp when moving for a better indication. I'm not a big fan of 134a. If the temp drops measurably when moving then it's working as good as it'll get.


Len

 

[femurphy77]

59 degrees moving down the road at 60 mph or sitting in the driveway. That's what bugs me the most. I would have figured I'd see at least another 5-10 degree drop motoring down the road. I'm taking these measurements from the center vent with an analog and a digital thermometer and they both agree to within a degree. I'm probably going to "unconvert" this thing once I get my EPA Cert but until then I'd like to see some improvement with the cards I have on the table. I don't know if adding any refrigerant would help. I didn't want to overfill it so I stopped adding once the clutch stopped cycling.

 

[JonM]

Want your EPA?...easy http://www.epatest.com/

 

[Robertwav1]

I've been working on the AC in my '92 pretty much all weekend and am not satisfied with the results. I've replaced the orifice tube, vac'ed the system down to 30" for 6 hours and added about 26 ounces of 134. Everything seems to be working but in an outside air temp of 94 degrees, humidity around 60% my center outlet temp on max cooling settings is only 59 Degrees. I am by no means an AC mech but do pretty decent in most of my mechanical endeavors. Low Side pressure is 32# and hi pressure is around 300#. I have plenty more refrigerant but basing the amount on 80% of the r12 charge I should have enough. The car had 134 fittings on it when I got it so I don't know the history of the conversion. Everything seems to work but I'm just not getting sufficient cooling. AM I asking too much? TIA, FM, Indy.

Low side sounds a bit shy for such a hot day. I usually run the engine up to 1500 to 2K RPM and check my pressures then. 134a will be a little higher then 12. 12 runs around 33 PSI and 134a around 36 PSI on a nice hot day. Head is high cause no air crossing the condenser if your just idling. Temp readings are good. How does the cooling feel getting back to the compressor? No icing though! I rarely go by the amount the system says it holds....it's almost never right. Going down the highway the temperature should drop off even more...the colder it get inside the vehicle, the colder the air will become. My opinion!

 

[nyernga]

Head is high cause no air crossing the condenser if your just idling.

Just a thought but is your condenser clean? It's easy enough to check and clean if it is.........

Len

 

[G Winter]

If yours is like any other GM car, on Max air you recirculate inside air. What you need is to compare the temp inside the car with the air coming from the center vent. If you have 35 deg temp diff standing still you can't expect much more. A very large fan in front of the car would help. But like others have said driving down the road is a better test. Expect nothing over a 50 deg drop. If you get that you have an excelent system. In one of the threads about air. one member mentioned using a ford orifice tube which is a diff size.