gpuck16

I have a 2003 Civic EX. The AC is warm when idle at a stoplight (80+ degrees), but when driving down the road I am getting low 60, high 50 degree air.

The compressor clutch engages and runs when AC is turned on from the dash. The condenser fan and radiator fans are running when the car is idle. The system is fully charged with r134a.

Everything appears to operate, but I can't troubleshoot what is causing the AC to run warm when the car is idle.

Any possible suggestions on items to troubleshoot?

sumdewd

Are the fans turning the correct direction into the engine bay? Is your idle low? Is your condenser dirty? How hot is it outside? Can you raise the idle up in neutral to see if it cools better? Additionally, could you mist (Mist, not soak) your condenser with water to see if it starts cooling better?

Without verifying a proper drain and fill from a deep vacuum, then charged by weight with a scale, it's kind of a guessing game. You're very likely missing either airflow or compressor volume. Revving the engine to 1500 at an idle and not moving would be a good way to help isolate this. Misting the condenser will also help temporarily cool the A/C down if you are missing airflow.

Does the outer hub of the compressor still spin when it's blowing warm? And last but not least, have you had manifold gauges (Not a walmart can or gauge) on it to check the pressures against the outside temperature? It would be way easier to help diagnose with a possible weak compressor if you can get some readings at idle and 1500 rpm.

gpuck16

The fans are OEM and when I put my hand behind them the air is blowing towards the engine. The idle is around 700 rpms. I quickly cleaned the condenser with once of those sprays and rinsed it off, but that is likely not much of a cleaning. I plan to take the bumper off and clean it well with simple green or engine cleaner and a soft paint brush to agitate.

The outside temperature in the shade is 87 and in the sun I venture to say high 90s low 100s. The car is the nighthawk black so the hood in the sun right now exceeds 160. When I run the car at neutral the AC temperature cools much better, dropping it from the 80s to the low 60s very quickly.

Misting the condenser with water did drop the temperature around 10 degrees.

The outer hub of the compressor does still spin when the air is blowing in the 80s. If the compressor is weak would removing the clutch hub, cleaning it up help at all? Also would removing a shim make any difference?

I do not have manifold gauges, just the cheap one.

Is it possible the condenser fan, though running, is not relaying the information to the system while idle? Also could the relay from the compressor cause this same issue?

sumdewd

Do you have access to a set of manifold gauges? It's still a guess without those pressure readings. You could greatly help your idle temperatures if you seal the condenser to the radiator by making a custom shroud, or by sticking foam weatherstrip to the edges while you have the bumper off. The goal is to force the radiator fans to pull through the condenser, not around it, which can greatly improve idle/low speed performance. Honda does a really freaking bad job at this.

Removing the clutch hub would not help the compressor at all unless it was slipping. The only job of the clutch is to literally toggle the compressor on and off by locking it to the pulley to spin.

This is kind of what I mean with the foam tape with an image stolen from google:


Once again, it's tough to judge without getting a reading from a set of manifold gauges while the issue is happening. Let us know if the condenser is dirty, and do what you can to clean and seal it to the radiator. This is probably one of the most free or cheap options at this point.

Edit: These cars do not have 2 speed fans. They try to run at the same speed at all times. Relays are typically on/off for this model year. I don't think you have a relay issue since you state both fans and the compressor clutch all come on.