I have a 2000 Civic. I replaced the compressor, discharge line/tube that was leaking, replaced the receiver drier, replaced schrader valves and caps, added in the recommended amount of PAG oil, put the system under vacuum and noticed no leaks, and recharged with the recommended 22 ounces of R134a.

AC compressor kicks in and fan is running but blows WARM at idle, ac blows cold when car is moving or if I increase idle RPM. Is it possible the A/C fan is not spinning as fast as it should; is there any way to diagnose or service something like that, save replacing it.

 

When you filled the R134A, did you have a gauge so you can see if you actually have the right amount in there? I've never just put the amount recommended, always used a gauge until it was in the green zone with the temperature adjustment slider on it (air con will read differently at say 40 degrees vs 100 degrees).

you might be just a little low or high.

 

Yeah I have a ac manifold gauge set and I added 22 ounces by weight.

 

Did the compressor fail? If so, you must also replace the condenser, evaporator, and expansion valve. You also need to flush the A/C lines.

 

The condenser fan PULLS air from the front towards the rear, that's normal, yeah?

 

Correct. It should.

 

Yes it is possible that the AC condenser fan can fail. You can replace the relay to see if that changes anything as the relay can become weakened over time

You also want to monitor the high side ac pressure to see if the temperature of the condenser is affecting pressures in the system. It will also help to watch the pressure to see if the AC pressure switch is working correctly.

 

I'm still trying to figure out why the performance is related to RPM. Is it possible the cheap replacement compressor I bought is weak?

 

Study the A/C circuit diagram for your car. Do you know why the compressor clutch relay is controlled by the ECU?

 

I'm not sure what you're trying to show me with that diagram, I don't totally understand it.

The compressor did fail but I only replaced the compressor, condenser and drier, because I was told that if there were pieces in the system, it would have been collected and stuck in those components.

 

The evaporator and condenser accumulate most of the failing compressor's metal debris due to having the highest internal surface areas. And you should never re-use the expansion valve after a compressor failure. I hope you get lucky, but only time will tell.

The ECU is integrated into the A/C circuit because it has an important function (idle speed control) in ensuring that the A/C system runs smoothly and efficiently.

 

Well it's bearable for the meantime, since I really don't feel like opening the system again. But I suppose if I ever get eager enough to continue the repairs; replacing the evaporator and expansion valve should solve the issue?

 

I don't have access to your car, so I can't diagnose what ails it. What I can do is try to point you in a direction based on what information you have shared.

For example,

1) Describe the engine behavior when the A/C blows warm at idle.
2) Performance test your A/C system (detailed in service manual) and plot the results on chart provided there.

 

You don't need the station shown in the diagram. A manifold gauge set is sufficient.

 

 

Are you absolutely certain that the condenser fan runs and compressor clutch stays engaged when the A/C blows warm with the engine idling?

 

I did that test just now while ambient temperatures were cool; AC has no issue blowing cold air during idle. It seems as though it struggles when ambient temperatures are warm/hot and at idle. Condenser fan and compressor clutch engaged is confirmed.

It seems as though the High side pressure is low and the low side pressure is high.




I will attempt to do the test again when ambient temperatures are warm during the day.

 

Did you follow these instructions? If so, the compressor may be faulty.

 

There we go, posting FSM pages like a boss

 

If the low side pressure is high while the high side pressure is low, your expansion valve is not functioning properly

This can be from contamination from debris like leaves and grime or a bad expansion valve

The compressor pushes the Freon pressure to the expansion valve where the valve restricts flow, similar to putting your thumb over a garden hose. When the Freon exits the expansion valve at high pressure and high velocity it becomes cold

If you have a 98 or newer civic there is a door where there would be a cabin filter behind the glove box. If you take off that little plastic cover you can reach in and try to remove debris inside to help the evaporator core and the expansion valve regulate the pressure by blowing air through the core

 

It shows you've been a member here for 18 years! Congrats! Have you had the same civic this whole time on honda-tech or have you had several? Random question I know but just curious

 

Its possibel the fan isn't spinning fast enough, I've had that happened.

 

I have also had that happen. The condenser fan usually fails completely within a few days or weeks of that happening

 

Hah, yeah same Civic, original owner.

 

It was a thought I had but when I look at it when it's on, it spins pretty darn quick.