I've got a 2007 Hyundai Elantra that's got a mostly-functional AC, but consistently blows warm air when at lower speeds (or idle) on warm days.

So far, I've tested the following:

  1. I press the A/C button and I see under the hood that the clutch starts/stops spinning
  2. When I drive on the freeway, the A/C blows cold 100% of the time
  3. When I coast downhill at around 40 mph, the A/C begins to blow cold
  4. I got one of those all-in-one A/C refill canisters from O'Reilly and before I even tried to add refrigerant in there, the gauge told me the pressure is normal (so I ended up returning the refill canister)
  5. The condenser fan sounds louder than I would expect (compared to my other vehicles -- a minivan and a V8 truck)

Another thing I noticed just the other day is that when idling in my driveway, the A/C clutch stops/starts randomly -- I'm not sure if this is a sign of a bad clutch, or something thermostat-triggered.

I'm starting to think that the condenser fan needs to be replaced. Would you agree? Or should I swap out the entire compressor (since swapping out the clutch would basically require removing the compressor anyways)?

  • Welcome to Motor Vehicle Maintenance & Repair! Sep 9, 2022 at 9:49

2 Answers 2


A couple of things ... is there anything obstructing the air flow through the condenser? Like a plastic bag or something. Rapid clicking of the A/C clutch is usually an indication there is a low refrigerant charge. If you haven't looked at both high/low side readings, while compensating for ambient temperatures, then you don't really know if your charge is low or not. If you don't have a manifold gauge which will show you both pressures, you should take it to an A/C shop to have it tested.

  • nope, no obstructions in the condenser. I'll give the manifold gauge a try. Thanks!
    – richyen
    Sep 9, 2022 at 16:08
  • My opinion; 98% of vehicle ac problems are the eventual leaks occurring, many run to the store for a refill kit that basically refills..................a leaking system. Sealer is never used in repairs. Sealer contaminates and damages systems, making a mess and more money for repair shops having to replace parts and flush a system of sealer that will contaminate a repair costing more than if sealer were never used. Know anyone using ac sealer that still works into the second summer cooling season? Gauges should show low side around 35 psi, high side between 125-250 psi (above idle rpm).
    – F Dryer
    Sep 9, 2022 at 21:31
  • @FDryer - As long as you compensate for temperature. Sep 10, 2022 at 0:08
  • 1
    You did not say if you have opened the car since new, or bought used. I’ve seen this happen before (although it’s a long shot) where the fan was replaced, and it was wired backwards so the fan pushes air forward through the radiator and the condenser. When idling or driving slow hot air is trying to push forward while air is trying to be pushed in the front from vehicle movement, so no airflow. Move fast (Highway speed) and it overcomes the fan, A/C starts working. Check the direction of fan rotation and fan blade angle to make sure it’s pulling air in from the front of the car.
    – X-tech2
    Sep 19, 2022 at 17:32
  • The other possibility based on your comment is a vacuum issue. If you have vacuum operated mode doors and heater control valve, you could be getting partial heat mixed with your cold air, making you think it’s an A/C issue when in fact it’s working fine. Small amount of vacuum at idle, not enough to overcome a leak. Lots of vacuum at highway speeds, and going downhill, enough to overcome the leak? I would look at your vacuum lines too. Check the hose going into the cabin and put a tee and vacuum gauge on it. See if it loses vacuum quickly if you pinch off the line.
    – X-tech2
    Sep 19, 2022 at 17:42

I was able to resolve the warm AC by replacing the condenser fan. After replacing it, I noticed the new one (which I pulled out of a 2010 Elantra) was much quieter. I also noticed that the old one had a thermocouple that looked cracked and crusty -- that was probably contributing to incorrect readings, and I assume probably caused the compressor clutch to disengage at wrong times.

I didn't get to fully test @X-tech2's suggestion, but that may have been a possibility. I noticed that after installing the new fan the air blows inward; not sure if my memory is playing tricks on me, but I do recall the old fan blowing outward, so yeah maybe @X-tech2 was right about that. The cracked thermocouple looks like it needs to be replaced anyways, and it runs loud, so I'm not going to bother fixing the orientation of that old fan.

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