Automotive Air Conditioning Information Forum

Hey guys!

Could a compressor be faulty even though it’s turning, both high and low pressures are fine, suction line is icy cold and high pressure is not too hot?

I had a daihatsu Gino in recently where the pressures were low slightly low so I topped them up, to where everything seemed prefect apart from the fact the air inside the car wasn’t cold but slightly cool.

I thought there could be air in the system? Apart from that I could think why else. Is the expansion valve was faulty wouldn’t either the suction side not get cold or the high pressure get really hot?

Thank you in advanced.

Check for hot air getting into the cab of the vehicle. Cold suction line, proper pressures lead me to other issues and not a compressor.

Davey boy wrote: ↑Thu Nov 18, 2021 6:55 pm Could a compressor be faulty even though it’s turning, both high and low pressures are fine, suction line is icy cold and high pressure is not too hot?

If the pressures are good, especially the high side, and the lines are at the expected temperatures, chances are it's not the compressor.

Davey boy wrote: ↑Thu Nov 18, 2021 6:55 pm I had a daihatsu Gino in recently where the pressures were low slightly low so I topped them up, to where everything seemed prefect apart from the fact the air inside the car wasn’t cold but slightly cool.

Sounds like this vehicle is a Japan-spec car (model year not mentioned), which I don't have information on. However, its A/C system is small, capacity wise, holding less than a pound of refrigerant, I believe. So cooling can be affected if the refrigerant amount is off by only a tiny amount. Instead of guessing and topping-off by an unknown amount, it would be best to recover, evacuate, and recharge exactly to specs before diagnosing further.

Davey boy wrote: ↑Thu Nov 18, 2021 6:55 pm I thought there could be air in the system? Apart from that I could think why else. Is the expansion valve was faulty wouldn’t either the suction side not get cold or the high pressure get really hot?

Could be yes to both questions. Air in the system, if suspected, would have to be removed by a thorough evacuation and then recharging to specs. I would also change the desiccant. A TXV problem can be caused by a defective valve that's stuck open or closed, or if it's not defective in and of itself, by something blocking it. If you have a TXV issue, you'll see abnormal gauge readings in addition to off-temperature lines, which you inferred that you don't have.

If the charge is spot-on, the engine-compartment fan(s) are running as they should, and the pressures are in range for a given ambient, then I agree that you're probably looking at a "re-heat" issue as previously suggested.

What makes you think there is a problem at all?

Some A/C systems are just weak performers by design, i.e. small compressor, low evaporator airflow.

Hello!

Thank you for all your detailed reply’s!

I have worked on the same car and know it’s AC full potential and this is no where near it. When starting the engine after leaving it over night it still produces the same, not cold but mildly cool air. I guess it must be air in the system huh?

Unfortunately the person has took their car and I’m not sure when or if they will be back. If it comes back I will do the evac and put the correct amount of gas in and report back!

Thank you again.