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I am having a problem diagnosing the AC on an 04 Civic. The compressor comes on, system has 52lbs charge on low side but no cold air blowing. The hard line coming out from firewall is a little colder than outside temp. but not much. This is my girls car and I am not very familiar with it but would like to do what I can with it before I take it to shop. Any help from anyone who has dealt with this before would be appreciated!

 
Rep Power: 313

Very vague description of the problem is hard to diagnose. If it's pressurized properly then you have to find out what's going on with it. Is the compressor coming on? Are the two radiator fans coming on when the AC is on? There is a thermal protection unit on top of the compressor that is prone to going. It could also be the compressor clutch system or the electronics that run it, or the compressor itself could be faulty. If you don't have much experience working on these systems you will need to take it to a shop.

 
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Compressor comes on as it should,both electric fans come on as they should.No problems with overload thermister. I have heard this generation civic is known for expansion valve issues.Anyone have any experience troubleshooting/testing valve?

 
Rep Power: 518

Was this reading taken with the AC operating, or with the engine shut off?

What is the high side pressure while the AC is operating?

What was the engine RPM when these readings were taken?

What is your ambient temp?

Yes.

 
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Reading was taken at idle with AC on @ ninety degrees.High side 250psi @ same temperature.

 
Rep Power: 518

That's probably too high on the low side then.

If you run the engine at 2000 RPM, what are the pressures now?

Both radiator fans run?
Blend door moves all the way to its cold position?
Heater core water valve closes completely?
Recirculate door and servo work properly?


Run the engine at 2000 PRM, doors wide open, recirculated inside air for 10 minutes, take some readings:
What is the ambient humidity
center vent temperature
side vent temperature, both left and right sides
intake air temperature (glovebox areea for recirculated air)
Meh, who cares about all that........besides me?
This info would be looking for how much temp drop occurs in a single pass across the evap core, and humidity will cause a lot of variable in that reading.



Correct R134a charge, by weight? (0.50-0.55kg, or 17.6-19.4oz)....not some funky stuff that isn't R134a?

I'm gonna wild guess the vent temps are around...um...60*F along with the suction pipe, and the low side drops a bit when you rev up the engine? Could be an expansion valve stuck, yes.

I might take a long screwdriver and tap the x-valve while watching pressures to see if that changes pressures at all. If low side pressure drops when you smack the exp valve, then that would indicate it was stuck.