134a Converson gone bad

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Jul 11, 2004 | 08:23 AM

F150'89

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From: Roland, Ar

134a Converson gone bad

I have converted 3 of my R12 systems to 134a and have had good results with 2 of the systems. All 3 three systems were redone the same way: new compressor, dryer, orifice tube, Pag oil, flush & vacuum down. #1 '89 F150 will cool to 34deg vent temp while driving, #2 '82 Buick Regal will cool to 38deg vent temp and #3 '89 S10 Blazer will only cool to 60deg while driving. I installed a auto adjusting oirfice tube to see if it would help and it did not. My wife drives the Blazer and she is not very happy! I removed the front grill and used a aluminum wheel cleaner on the condersor to help clean it, its cleaner but did not change anything. BTW the low side pressure at idle is 40psi and the high side is 195psi, at about 200rpm the low side is 30psi and the high is 225psi Can anyone HELP!!!!

Jul 11, 2004 | 11:55 AM

Pikachu

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From: Amarillo, TEXAS!

Hmmm.... Pressures sound OK. Was this a working system before the R134 went in it? Not knowing if that vehicle uses a hot air/cold air blend system or a valve to control the heat, I can only recommend you make that determination and see if it is functioning properly. Also, the vehicle is 15 years old, could the evap coil be all plugged with miscellaneous glop? My '99 was pretty cruddy, and cleaning it helped.

Jul 11, 2004 | 01:11 PM

F150'89

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From: Roland, Ar

The A/C system worked last year but the compressor leaked oil/freon from around the back side. There is a heater blend door and it works properly, I even installed a manual shutoff valve in the heater hose to stop the flow of coolant to the heater core. If I have time I will look at the evap.

Jul 11, 2004 | 04:24 PM

F150'89

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From: Roland, Ar

Ok I opened the evap box and removed about a sandwitch baggie full of crud and then used a shop vac to remove anything in the evap itself. Result is now 55deg vent temp while moving a 50mph.

Jul 11, 2004 | 07:19 PM

Pikachu

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From: Amarillo, TEXAS!

Vent temps should still be lower than 55 on max. Does it cool well to start with, and get progressively worse, or does it just start out poorly? If it is OK at first, it could be icing up. Does the compressor cycle on and off if you maintain about 2000 rpm's? Its probably something simple, but I can't seem to put my finger on it.....

Jul 12, 2004 | 06:36 PM

F150'89

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From: Roland, Ar

When I started the a/c after cleaning the evap the temp inside the truck was at 120deg and the temp started to drop until it reached 60deg and this was at idle. Took truck on a 10ml road test and the best it would do is 55deg. The low side preasure at 2000rpm is 30psi and the high side is 225psi and the compressor never stops running.

Jul 12, 2004 | 08:33 PM

Pikachu

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From: Amarillo, TEXAS!

OK. Now I'm stumped. It sounds like it should be putting frost on the windows. The only other thing I can think of is the recirculate door. If it isn't closing off the outside air, it won't get nearly as cold in there. You should be able to hear the difference in the sound of the airflow when you go from Max A/C to Norm.