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Ask Ricardo Hohl Your Own Question
Ricardo Hohl
Ricardo Hohl, Master Certified Tech
Category: Chevy
Satisfied Customers: 4300
Experience:  Automotive instructor at Porter and Chester institute
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2002 chevy astro van. just replaced the AC compressor. went

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2002 chevy astro van. just replaced the AC compressor. went to charge it and the comp kicks in but no cold air and there is no pressure diff between the high and low side on the AC lines. Check Valve gone bad?
JA: Do the vents feel cold? Is there a coolant leak?
Customer: system holds the coolant but no cold air.
JA: Are you fixing your Astro yourself? What have you tried so far?
Customer: Yes I'm doing the repair. like i said just replaced the AC Compressor
JA: Anything else you want the mechanic to know before I connect you?
Customer: nope

Good Morning and welcome to just answers my name is Ricardo. can you tell me the pressures on the low and hi side, how many ounces of Freon did you charge it to.

Customer: replied 1 month ago.
pressure is the same at both sides, I have no number. One large can almost, 20 oz's maybe.

OK if the pressure is the same on both then the problem is the compressor not pressurizing the Hi side ( liquid side) to turn it in to gas on the low side

Customer: replied 1 month ago.
Brand new Compressor,
Customer: replied 1 month ago.
just installed.

the compressor is there to compress Freon gas in to liquid therefore the liquid side should be hi 150 to 200 and the low side should be 20 to 30 pounds on gas

if you have equal pressure then your compressor is not compressing or not turning the clutch on?

is the clutch engaging?

Customer: replied 1 month ago.
clutch is engaging

then the compressor is not good

Customer: replied 1 month ago.
why is the pressure the same on both sides?Check Valve in the compressor is faulty?

did you put the Freon with the can upside up or down?

Customer: replied 1 month ago.
upside down, not first rodeo.

did you put it on the low side?

Customer: replied 1 month ago.
fitting only fits the proper side to fill on.

upside down goes in as liquid...upside up goes in as gas low side should have been upside up.

putting the can upside down forces the compressor to compress liquid when it can only compress gas

yes the valve probably when bad.

Customer: replied 1 month ago.
ok, system was totally empty(hi side and low side) after installing the new compressor, tell me proper way to recharge system then?

when installing a new compressor make sure you put PAG oil at least one once, and if charging through the low side (gas side) put the can upside up this will take a little longer but will not damage the compressor.

as you put the new can the low pressure switch will sense gas low and force the compressor to turn on this will suck the rest on the can.

one best way to get an effective system cold is by pulling a 15 minute vacuum to the system before adding Freon . this will remove excess water and contaminants and will make good room for the new Freon to work effectively.

Customer: replied 1 month ago.
ok, good stuff here. I'll look into it.

Napa auto parts will rent you a vacuum pump for this job.

very good let me know if you need more information and help thank you.

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