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Vacuum not holding

toddy457 on Mon July 11, 2011 1:44 PM User is offline

Year: 2000
Make: Chevy
Model: Blazer
Engine Size: 4.3
Refrigerant Type: R134a
Ambient Temp: 90
Pressure Low: 0
Pressure High: 0
Country of Origin: United States

Hello everybody. I'm working on a 2000 S10 Blazer. 163,000 miles. I just put in a brand new compressor and accumulator. Obviously the system is empty. I hooked up a 1.5 cfm vacuum pump and after about 45 minutes, it would only get down to 25 hg I then closed both valves on the gauges and turned off the pump. After about 30 minutes, it's lost all of the vacuum so, I guess it's obvious there is a leak. I'm just learning this stuff. My question is, where is the most likely place for the leak to be since the compressor and accumulator are new? Am I just doing this wrong?

I hooked up my gauge set Mastercool 66773. I hooked it to the truck and to a Mastercool 90059 pump. I opened both manifold valves and turned on the pump. I'm using the quick connect couplers to hook to the service ports. Am I missing something? What should I do next? Thanks for your help.

Cussboy on Mon July 11, 2011 2:52 PM User is offline

Last year when I installed a new accumulator on my '94 Suburban, one of the O-rings supplied was thinner than what was on there. So I went back and got a thicker O-ring for that.

toddy457 on Mon July 11, 2011 7:52 PM User is offline

Funny you mention that cussboy. I noticed the same thing. I vacuumed again and it seemed to hold. It still didn't get quite to 30 but it was holding. Added some dye and, charged it up with about 29 ounces of 134a. I got a vent temp about 60 but it felt colder than that. It was cooling pretty good. Low pressure at 1500 RPM was 35 while the high side was 265-270.

I'll see what it does.

GM Tech on Mon July 11, 2011 11:09 PM User is offline

S-10s use slimline sealing washers on the compressor manifold-- did you replace them with the proper sealing washers?

The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

toddy457 on Mon July 11, 2011 11:15 PM User is offline

Hey GM tech, yes I went right to the dealer and got them. Is it ok that the vacuum only got down to about 27 or28? Thanks for your help.

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