please help 1996 silverado a/c pressures

- S
- stryped
  
  Contact options for registered users
posted
12 years ago

Sat, Aug 27, 2011 10:09 PM

I posted awhile back but did nto get alo of direction so I did some tests and thought I would post them. I re did my truck ac. New condensor, new compressor and even a new line and dryer all fdrom autozone. Puled a deep vaccum and it held.

When I did the test the weather radio said it was 89 degrees at a town

30 miles from me. The report was 30 minutes earlier so I think it may have been even hotter.

Had wife hold the accelerator at around 1500 rpm. AC on max windows down. Low pressure started at 45- 50 and after about 2 minutes it slowly creeped down to 40. It stayed at 40. took a few minutes to creep down. High side was right at 200. I dont like my vent thermometer too much but it looked like it said 64 degrees.

before I did this test ttruck had idled for about 10 minutes. (Maybe a little less)

When I pulled the high and low pressure hoses off, oil chot out of both hoses. I am not sure if this is normal or not. I put the recommended pag oil that was given to me when I installed everything. I put part in the compressor, part in the dryer, part in the condensor.

Problem with truck is it wont cool well at idle or when first taking off. It seems it has to go down the road at interstate speed for 3 or more miles before it really starts to cool. Fan clutch has been replaced. When I turn the heater on hot air comes out so I assume the temp door is working.

One other thing is while reving it I dont think the compressor is cycling off. It just stays on. The compressor was a new one not rebuilt from autzone.

I appreciate any advice.

- W
- willameena
  
  Contact options for registered users
Vote on answer
posted
12 years ago

Sun, Aug 28, 2011 11:15 AM

Stop working on it. Stop pretending to be a mechanic. Learn english. Learn how to spell.

- V
- Vic Smith
  
  Contact options for registered users
Vote on answer
posted
12 years ago

Sun, Aug 28, 2011 2:04 PM

I've found high/low pressures are only "general" indicators. Often off 10 or more psi when system works well. Called for refrigerant weight is what to look for. Measuring vent temp tells the story. You have to let the temp stabilize to best temp, which means all parts are cooled getting a final temp. What I do is load with the spec weight of refrigerant, and stabilize the temp on the vent. Since can weights don't add up to spec weight, I add a little at a time, shutting off flow, wait, and see if temp goes down. Probably a couple ounces at a time. Quit when temp doesn't go down. You'll never know if you've loaded exact spec weight, but if you use that procedure you won't overload it.

64 when ambient is 90 doesn't sound bad. But unless you stabilize before you measure 64 might not be accurate. Thermometers are cheap, and there should be no questions about that.

If you put in the called for amount of oil don't worry about it. I just shoot it in the low side when I've replaced a compressor/dryer and never had an issue. Can't say I'm an expert, just what's worked for me.

Wouldn't hurt to check that the doors are closing right.

Pretty sure the compressor will stay on when it's hot outside. Never noticed mine cycling in hot weather. V5.

I'm never really satisfied with the temps when I do this, but the A/C keeps me cool anyway. If the truck sits in the sun or just high heat it takes a while to cool everything and get decent vent temp. Some vehicles have better parts insulation and cool quicker.

--Vic