AC on my '99 Century

[turbojimmy]

Well it's official. Everything I paid the dealer for last year was a total waste. I paid them over $2,000 to fix a looseness/clunk in the front end and to find and fix a leak in the A/C system. Front end problem never was fixed, and now the a/c system has leaked down to where it's barely cool.

It first seemed like there was something wrong with the driver/passenger climate control because it started out with the driver's side air being a bit warmer than the passenger side air. Now the driver's side air is plain old warm and the passenger side air is just a tick cooler than "warm" (actually it's about 70 degrees). I'm pretty sure the doors are functioning properly - I can see the electric motors turning them. Maybe it's just the way the system behaves when it's low on refrigerant? The temp diff between the sides might not be noticable when it's charged properly? Anyone know anything about these split-temp-controls systems? The manual says to check the outlet temp in the right center, which would be the coolest.

Refrigerant pressure is 25-30 and 175-200. According to the service manual, pressure should be 30-50 and 200-310. Ambient temp is 80 degrees, humidity is 70 degrees. At that temp and humidity I should be at 37 and 300 psi. The catch is that the manual specifies that the RPM should be at 2000 RPM to get those readings. I'm pretty sure the car isn't idling at 2000 RPM. The manual just says "stabilize engine at 2,000 RPM". Would there be a big pressure difference between idle (say 800-900 RPM) and 2000 RPM?

Sorry for the long post - tired of sweating with my AC on.

Thanks,
Jim

 

[TurboJim]

Originally posted by turbojimmy

Refrigerant pressure is 25-30 and 175-200. According to the service manual, pressure should be 30-50 and 200-310. Ambient temp is 80 degrees, humidity is 70 degrees. At that temp and humidity I should be at 37 and 300 psi. The catch is that the manual specifies that the RPM should be at 2000 RPM to get those readings. I'm pretty sure the car isn't idling at 2000 RPM. The manual just says "stabilize engine at 2,000 RPM". Would there be a big pressure difference between idle (say 800-900 RPM) and 2000 RPM?

Sorry for the long post - tired of sweating with my AC on.

Thanks,
Jim

You're undercharged Jim. I dont know about 310psi, but in a 134 system on a day like weve been having, 35-40 on the low and somewhere around 250 on the high at idle is where I'd shoot for. I'd say 3/4 lb or so low.

As for presure diff, yes, high side will be higher, and low side lower. Somewhere around 30psi and 260-275 or so. This is sitting still. On the road with airflow thru the grill, pressure on high side will be lower.

 

[turbojimmy]

Thanks Jim. I'll shoot for those numbers. I guess I'll just pick a can up of R134a up at Wal Mart and see what happens.

What kills me is that when I brought it to the dealer I told them where I thought the leak was. My brother boogered up a fitting where the lines meet the evaporator core. I was too lazy to replace it and figured I'd just pay the "professionals" to fix it. They said there was no leak at the evap core and that it was where the pressure switch attached to the line. I didn't think it was leaking there, but hey - they have the test equipment. They replaced the O-ring and charged me R-12 prices for an R134A fill. That f'n line is still leaking at the evap core. If I can nurse it through the season I'll replace it over the winter.

And there was a typo in my post. Humidity is measured in %, not degrees. So humidity is 70% today. I hate when I do that and hate it more when I can't edit my post.

The 310 was the top end of the chart, 90 degrees ambient and 90 degrees humidity and 2000 RPM.

Jim