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Inefficient Condensor or R134a overcharge ?

y2k600f4 on Fri August 06, 2010 11:27 PM User is offline

Year: 1980
Make: Chevrolet
Model: Camaro
Engine Size: 350
Refrigerant Type: R134a
Ambient Temp: 87
Pressure Low: 30
Pressure High: 275
Country of Origin: United States

1980 Chevy Camaro R12 to R124a conversion less 2 yrs ago with all proper parts ordered from new orifice (white), accumulator/dryer, rebuilt A6 compressor, system flushed and proper BVA Auto 100 Ester amount, proper vacuum pulled, new o-rings etc original condenser and evaporator. During charge UV dye was added (system recently checked with UV light and no apparent leaks).

Performance engine w/headers that throws off a ton of heat !!!

-A/C running at idle ~275PSI high side and ~32-34 PSI low side,vent temp ~75F, Ambient 85-90F, 105F in front of condenser during idle (new cutch fan) . Windows open, A/C max:

-A/C off I get ~110PSI low/high

-Running highway A/C on max, windows closed I get lowest vent temp of 65F at same ambient temps, I was expecting around 50F (???) for a properly converted system….I am expecting either the system may be overcharged or the condenser is really inefficient. Any pointers would be appreciated.

Dave in Texas on Sat August 07, 2010 9:14 AM User is offlineView users profile

When you did the initial charge, did you install 80% of the R12 system capacity? My system required 38oz R12....converting to 134 calls for 30oz initial charge. R U sure there are no conflicts within the plenum system....heated air bleed-over.

At 2, I went home with a 10. At 10 I woke up with a 2 !!

y2k600f4 on Sat August 07, 2010 10:44 AM User is offline

The blender/plenum was suspect but I used my digital thermometer to measure the low pressure line going into the evaporator and it was only a few degrees cooler than the vent temp.


I went out this morning (cooler) ambient 82F and tooks some pressure readings:

-A/C off low/high side ~85PSI (car running)
-A/C running a few minutes (same procedure as before): vent 65F and High ~150 PSI and low cycle ~23-46 PSI
-I tried spraying the condensor with water, with no noticeable effect....I am guessing I would notice a larger effect if it was hotter out (90s+)

I would be happy to get ~10F cooling but not sure what is going on.

I hear of all these people doing improper R12 to R134 conversions and claim to get vent temps in high 30s, low 40s during high 90s ambient temps ????????

Edited: Sat August 07, 2010 at 11:50 AM by y2k600f4

Dave in Texas on Sat August 07, 2010 11:14 AM User is offlineView users profile

I did the conversion back in the mid-90s. I used the White orfice tube then. When I installed a new engine, in 2008, I used a Blue tube from recommendation of forum pro. Reason being to help flood the evap a tad longer. I can tell a difference but not a big one. On the highway in our Texas heat my vent air is 42dg on Max and lower on slower blower speeds. Driving around town is a different story, but the car is used only for road-trips. If I had to use car for both kinds of driving I would have changed the condenser to a PF type. If there is no problem within the plenum with the doors/etc. maybe the exterior of the evap is just extra-dirty. What was the 134 initial charge?

At 2, I went home with a 10. At 10 I woke up with a 2 !!

Edited: Sat August 07, 2010 at 11:18 AM by Dave in Texas

y2k600f4 on Sat August 07, 2010 11:49 AM User is offline

Problem is that I don't know what the current charge is. I did an engine swap last year and one of the connections on the compressor was loosened and I lost some freon. I re-charged with 1-1.5 cans and don't recall vent temps but I think at best maybe 60F at idle with ambient 85 (????) I never got really good cooling, I had the #s written down but since lost them during a recent PC crash (file).

I had the car idling for a while (engine temps climb up !!!) and ambient temps went up 5F or so to about 88 (probably a lot hotter at the condensor). I saw a rise on the high side to 225-250ish and a vent temp at idle still at 65F or so.

Took it for a short run and got vent temps at best 62-63F after car cooled down and got going down the highway. I am no expert but could of have lost some freon from last year ?

Dave in Texas on Sat August 07, 2010 2:06 PM User is offlineView users profile

If it was me, I'd evacuate the system. If it holds vacuum for an hour or so, then recharge with 80% of the R12 capacity.

At 2, I went home with a 10. At 10 I woke up with a 2 !!

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